0001558370-24-002174 | 10-K | XBRL Viewer

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Derivative Instruments and Hedging Activities - Summary of Commodity Derivative Activity (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commodity swaps
Derivative Liability
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Derivative Liability Current, Related Party
Not Designated as Hedging Instrument
Derivative Assets
Gross Amounts Recognized	$ 4,628	$ 6,755
Gross Amounts Offset		0
Net Amount Presented	4,628	6,755
Derivative Liability
Gross Amounts Recognized	1,875	3,845
Net Amount Presented	1,875	3,845
Not Designated as Hedging Instrument \| Commodity swaps
Derivative Liability
Gross Amounts Recognized	1,875
Net Amount Presented	1,875
Notes receivable and other long-term assets, net \| Not Designated as Hedging Instrument \| Fueling agreements
Derivative Assets
Gross Amounts Recognized	2,035	5,115
Gross Amounts Offset		0
Net Amount Presented	2,035	5,115
Prepaid expenses and other current assets \| Not Designated as Hedging Instrument \| Fueling agreements
Derivative Assets
Gross Amounts Recognized	2,593	1,640
Gross Amounts Offset		0
Net Amount Presented	$ 2,593	1,640
Current portion of derivative liabilities, related party \| Not Designated as Hedging Instrument \| Commodity swaps
Derivative Assets
Gross Amounts Recognized		2,415
Gross Amounts Offset		0
Derivative Liability
Net Amount Presented		2,415
Long-term portion of derivative liabilities, related party \| Not Designated as Hedging Instrument \| Commodity swaps
Derivative Assets
Gross Amounts Recognized		1,430
Gross Amounts Offset		0
Derivative Liability
Net Amount Presented		$ 1,430

Stockholders' Equity - Service-Based Stock Options (Details) - Service Based Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-based compensation
Vesting period	3 years
Contractual term	10 years
Number of Shares
Outstanding at the beginning of the period (in shares)	10,116,340
Granted (in shares)	3,030,439
Exercised (in shares)	(98,592)
Forfeited or expired (in shares)	(487,610)
Outstanding at the end of the period (in shares)	12,560,577	10,116,340
Exercisable at the end of the period (in shares)	8,117,695
Vested and expected to vest at the end of the period (in shares)	12,560,577
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 6.00
Granted (in dollars per share)	4.78
Exercised (in dollars per share)	2.38
Forfeited or expired (in dollars per share)	7.29
Outstanding at the end of the period (in dollars per share)	5.68	$ 6.00
Exercisable at the end of the period (in dollars per share)	5.54
Vested and expected to vest at the end of the period (in dollars per share)	$ 5.68
Additional option disclosures
Outstanding at the end of the period, weighted average remaining contractual term	6 years 8 months 15 days
Exercisable at the end of the period, weighted average remaining contractual term	5 years 7 months 17 days
Vested and expected to vest at the end of the period, weighted average remaining contractual term	6 years 8 months 15 days
Outstanding at the end of the period, aggregate intrinsic value	$ 5,369
Exercisable at the end of the period, aggregate intrinsic value	5,345
Vested and expected to vest at the end of the period, aggregate intrinsic value	5,369
Total unrecognized compensation cost related to non-vested shares	$ 11,000
Unrecognized compensation cost, weighted-average period	1 year 4 months 24 days
Total fair value of shares vested	$ 11,300
Weighted-average assumption used for grants
Dividend yield	0.00%	0.00%	0.00%
Expected volatility, minimum	75.20%	73.70%	76.80%
Expected volatility, maximum	76.60%	76.90%	96.80%
Risk-free interest rate, minimum	3.68%	1.52%	0.58%
Risk-free interest rate, maximum	4.73%	4.34%	1.31%
Stock-based compensation
Weighted-average grant date fair values of options granted (in dollars per share)	$ 3.30	$ 4.40	$ 5.90
Exercised during the period, aggregate intrinsic value	$ 200	$ 1,300	$ 10,100
Stock-based compensation expense	$ 11,700	$ 11,900	$ 9,900
Minimum
Weighted-average assumption used for grants
Expected life	5 years 10 months 24 days	5 years 7 months 6 days	5 years 7 months 6 days
Maximum
Weighted-average assumption used for grants
Expected life	6 years 2 months 12 days	5 years 10 months 24 days	5 years 9 months 18 days
Vesting over the first year
Stock-based compensation
Vesting percentage	34.00%
Vesting over the second year
Stock-based compensation
Vesting percentage	33.00%
Vesting over the third year
Stock-based compensation
Vesting percentage	33.00%

Summary of Significant Accounting Policies - Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Goodwill impairment	$ 0	$ 0	$ 0
Goodwill	$ 64,328	$ 64,328	$ 64,328

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References + Details

Revenue from Contracts with Customers

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Revenue from Contracts with Customers

Note 2 —Revenue from Contracts with Customers

Disaggregation of Revenue

The table below presents the Company’s revenue disaggregated by revenue source (in thousands):


	Year Ended December 31,
	2021		2022		2023
Product revenue:
Volume-related
Fuel sales⁽¹⁾	$	130,973	$	281,103	$	286,956
Change in fair value of derivative instruments⁽²⁾		(3,490)		517		(158)
RIN Credits		31,736		34,635		25,860
LCFS Credits		16,808		12,634		9,885
AFTC ⁽³⁾		20,700		21,760		20,854
Total volume-related product revenue		196,727		350,649		343,397
Station construction sales		16,406		22,346		26,427
Total product revenue		213,133		372,995		369,824
Service revenue:
Volume-related, O&M services		41,934		45,901		52,660
Other services		579		1,268		2,675
Total service revenue		42,513		47,169		55,335
Total revenue	$	255,646	$	420,164	$	425,159

(1)	Includes non-cash stock-based sales incentive contra-revenue charges associated with the Amazon Warrant for the years ended December 31, 2021, 2022 and 2023 of $83.6 million, $24.3 million and $60.6 million, respectively. See Note 13 for more information.

(2)

Represents changes in fair value of derivative instruments related to the Company’s commodity swap and customer fueling contracts associated with the Company’s Zero Now truck financing program. The amounts are classified as revenue because the Company’s commodity swap contracts are used to economically offset the risk associated with the diesel-to-natural gas price spread resulting from customer fueling contracts under the Company’s Zero Now truck financing program. See Note 1 and Note 7 for more information about these derivative instruments.

(3)	Represents AFTC. See Note 1 for more information.

Remaining Performance Obligations

Remaining performance obligations represent the transaction price of customer orders for which the work has not been performed. As of December 31, 2023, the aggregate amount of the transaction price allocated to remaining performance obligations was $24.5 million, which related to the Company’s station construction sale contracts. The

Company expects to recognize revenue on the remaining performance obligations under these contracts over the next 12 to 24 months.

For volume-related revenue, the Company has elected to apply an optional exemption, which waives the requirement to disclose the remaining performance obligation for revenue recognized through the ‘right to invoice’ practical expedient.

Costs to Fulfill a Contract

The Company capitalizes costs incurred to fulfill its contracts that (1) relate directly to the contract, (2) are expected to generate resources that will be used to satisfy the Company’s performance obligations under the contract, and (3) are expected to be recovered through revenue generated under the contract. Contract fulfillment costs are recorded to depreciation expense as the Company satisfies its performance obligations over the term of the contract. These costs primarily relate to set-up and other direct installation costs incurred by NG Advantage, LLC (“NG Advantage”) for equipment that must be installed on customers’ land before NG Advantage is able to deliver CNG to the customer because the customer does not have direct access to the natural gas pipelines. These costs are classified in “Land, property, and equipment, net” in the accompanying consolidated balance sheets. As of December 31, 2022 and 2023, these capitalized costs incurred to fulfill contracts were $10.1 million and $8.9 million, respectively, with accumulated depreciation of $7.9 million and $6.9 million, respectively, and related depreciation expense of $0.5 million, $0.3 million and $0.2 million for the years ended December 31, 2021, 2022 and 2023, respectively.

Tourmaline Joint Development

In April 2023, the Company and Tourmaline announced a Joint Development Agreement to build and operate a network of CNG stations in Western Canada. Costs associated with station construction and profit and loss arising from station operation are shared 50-50 between the Company and Tourmaline (see Note 1).

The table below presents the financial information of the Joint Development with Tourmaline included in the consolidated statements of operations (in thousands):


		Year Ended December 31,
	2023
Revenue	$	322
Gross profit		98
Operating loss	$	(310)

Contract Balances

The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets), and customer advances and deposits (contract liabilities) in the accompanying consolidated balance sheets. Changes in the contract asset and liability balances during the year ended December 31, 2023, were not materially affected by any factors outside the normal course of business.

As of December 31, 2022 and 2023, the Company’s contract balances were as follows (in thousands):


	2022		2023
Accounts receivable, net	$	91,430	$	98,426

Contract assets - current	$	6,063	$	7,823
Contract assets - non-current		2,976		2,433
Contract assets - total	$	9,039	$	10,256

Contract liabilities - current	$	5,477	$	4,936
Contract liabilities - non-current		—		151
Contract liabilities - total	$	5,477	$	5,087

Accounts Receivable, Net

“Accounts receivable, net” in the accompanying consolidated balance sheets include billed and accrued amounts that are currently due from customers. The amounts due are stated at their net estimated realizable value. The Company maintains an allowance to provide for the estimated amount of receivables that will not be collected. The allowance is based on an assessment of customer creditworthiness, historical payment experience, the age of outstanding receivables, and economic conditions that may affect a customer’s ability to pay.

Contract Assets

Contract assets include unbilled amounts typically resulting from the Company’s station construction sale contracts, when the cost-to-cost method of revenue recognition is utilized and revenue recognized exceeds the amount billed to the customer, and right to payment is not just subject to the passage of time. Amounts may not exceed their net realizable value. Contract assets are classified as current or noncurrent based on the timing of billings. The current portion is included in “Other receivables” and in “Prepaid expenses and other current assets” and the noncurrent portion is included in “Notes receivable and other long-term assets, net” in the accompanying consolidated balance sheets.

Contract Liabilities

Contract liabilities consist of billings in excess of revenue recognized from the Company’s station construction sale contracts and payments received from customers in advance of the satisfaction of performance obligations and are classified as current or noncurrent based on when the revenue is expected to be recognized. The current portion and noncurrent portion of contract liabilities are included in “Deferred revenue” and in “Other long-term liabilities,” respectively, in the accompanying consolidated balance sheets. Contract liabilities of $5.5 million and $4.9 million were classified as current as of December 31, 2022 and 2023, respectively, and $0.2 million was classified as noncurrent as of December 31, 2023. No contract liabilities were classified as noncurrent as of December 31, 2022.

Revenue recognized during the year ended December 31, 2022 relating to the Company’s contract liability balances as of December 31, 2021 was $2.6 million. Changes in the contract liability balances between December 31, 2022 and 2023 were primarily driven by $4.9 million of revenue recognized relating to the Company’s contract liability balances as of December 31, 2022, partially offset by billings in excess of revenue and advances from customers recognized in 2023.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

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+ Details

Reportable Segments and Geographic Information (Tables)

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Schedule of revenue, operating income (loss), and long-lived assets shown for each geographic area


	2021		2022		2023
Revenue:
United States	$	252,310	$	416,975	$	418,754
Canada		3,336		3,189		6,405
Total revenue	$	255,646	$	420,164	$	425,159
Operating loss:
United States	$	(94,157)	$	(50,796)	$	(75,163)
Canada		(891)		(911)		(1,237)
Total operating loss	$	(95,048)	$	(51,707)	$	(76,400)
Long-lived assets:
United States	$	440,770	$	525,682	$	657,397
Canada		630		1,902		3,827
Total long-lived assets	$	441,400	$	527,584	$	661,224

Stockholders' Equity - Market-Based Stock Options (Details) - Market Based Stock Options [Member] - USD ($)		12 Months Ended
	Dec. 07, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-based compensation
Share price		$ 14.00
Threshold period of specified consecutive trading days within which common stock price to be trade to vest stock options		20 days
Minimum percentage of closing price of the Company's common stock on the market-based stock option grant date		207.00%
Contractual term		10 years
Number of Shares
Outstanding at the beginning of the period (in shares)		3,700,000
Granted (in shares)		0	3,700,000
Exercised (in shares)		0
Forfeited or expired (in shares)		(50,000)
Outstanding at the end of the period (in shares)		3,650,000	3,700,000
Exercisable at the end of the period (in shares)		0
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)		$ 6.77
Granted (in dollars per share)		0
Exercised (in dollars per share)		0
Forfeited or expired (in dollars per share)		6.77
Outstanding at the end of the period (in dollars per share)		6.77	$ 6.77
Exercisable at the end of the period (in dollars per share)		$ 0
Additional option disclosures
Outstanding at the end of the period, weighted average remaining contractual term		7 years 11 months 8 days
Outstanding at the end of the period, aggregate intrinsic value		$ 0
Exercisable at the end of the period, aggregate intrinsic value		0
Total unrecognized compensation cost related to non-vested shares		$ 0
Unrecognized compensation cost, weighted-average period		2 years
Total fair value of shares vested		$ 0
Weighted-average assumption used for grants
Dividend yield	0.00%
Expected volatility	67.80%
Risk-free interest rate	1.50%
Expected life	10 years
Stock-based compensation
Weighted-average grant date fair values of options granted (in dollars per share)			$ 4.87
Exercised during the period, aggregate intrinsic value		0	$ 0
Stock-based compensation expense		$ 8,200,000	$ 9,400,000	$ 200,000

Debt - Other Debt (Details) - Other debt $ in Millions	May 31, 2023 USD ($) installment	Dec. 31, 2023	Dec. 31, 2022
Long-term debt [Line Items]
Annual rate (as a percent)		13.38%	4.75%
Sale and leaseback arrangement
Long-term debt [Line Items]
Proceeds from sale of equipment in sale-leaseback agreement \| $	$ 0.3
Number of equal monthly installments \| installment	60
Sale leaseback transaction, term	5 years
Annual rate (as a percent)	13.38%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Summary of Significant Accounting Policies - Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Grant proceeds	$ 25.9	$ 24.9
Accumulated amortization of the grant proceeds	17.0	16.5
Amortization expense relating to grant proceeds	1.5	1.4	$ 1.7
Proceeds from grants	$ 1.9	$ 0.0	$ 0.5
LNG liquefaction plants \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
LNG liquefaction plants \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Station equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	10 years
Trailers \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	10 years
Other equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Other equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	7 years

Schedule II: Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowances for Doubtful Trade Receivables
Movement in valuation and qualifying accounts
Balance at the beginning of the period	$ 1,375	$ 1,205	$ 1,335
Charges (benefit) to operations	439	571	77
Deductions	(339)	(401)	(207)
Balance at the end of the period	1,475	1,375	1,205
Allowance for Doubtful Notes Receivables
Movement in valuation and qualifying accounts
Balance at the beginning of the period	5,499	4,755	4,105
Charges (benefit) to operations	1,041	744	650
Balance at the end of the period	$ 6,540	$ 5,499	$ 4,755

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued alternative fuels incentives	$ 41,609	$ 34,239
Accrued employee benefits	5,315	5,128
Accrued gas and equipment purchases	17,485	22,008
Accrued interest	1,451	1,827
Accrued property and other taxes	4,502	3,782
Accrued salaries and wages	8,697	6,857
Other	12,475	16,238
Total accrued liabilities	$ 91,534	$ 90,079

Stockholders' Equity - At the Market Offering (Details) - USD ($) $ in Thousands			12 Months Ended
	Jun. 08, 2021	Jun. 03, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 07, 2021	May 10, 2021
ATM Program Activity
Fees and issuance costs			$ 0	$ 0	$ 6,534
At The Market Offering
ATM Program Activity
Fees and issuance costs				6,500
Goldman Sachs & Co. LLC \| At The Market Offering
ATM Program Activity
Aggregate offering price						$ 100,000	$ 100,000
Gross proceeds				$ 200,000
Shares issued (in shares)	10,473,946	12,362,237		22,836,183
Fees and issuance costs				$ 6,000

Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Restricted Cash
Cash and cash equivalents	$ 104,944	$ 123,950
Total cash, cash equivalents and current portion of restricted cash	106,963	125,950
Total cash, cash equivalents and restricted cash	106,963	125,950	$ 106,456	$ 119,977
Amount in excess of FDIC and CDIC limits	105,600	124,800
Standby letters of credit
Restricted Cash
Restricted cash	2,019	2,000
Held as collateral
Restricted Cash
Restricted cash	$ 2,000	$ 2,000

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 15 —Commitments and Contingencies

Environmental Matters

The Company is subject to federal, state, local and foreign environmental laws and regulations. The Company does not anticipate any expenditures to comply with such laws and regulations that would have a material effect on the Company’s consolidated financial position, results of operations or liquidity. The Company believes that its operations comply, in all material respects, with applicable federal, state, local and foreign environmental laws and regulations.

Litigation, Claims and Contingencies

The Company may become party to various legal actions that arise in the ordinary course of its business. The Company is also subject to audit by tax and other authorities for varying periods in various federal, state, local and foreign jurisdictions, and disputes may arise during the course of these audits. It is impossible to determine the ultimate liabilities that the Company may incur resulting from any of these lawsuits, claims, proceedings, audits, commitments, contingencies and related matters or the timing of these liabilities, if any. If these matters were to ultimately be resolved unfavorably, it is possible that such an outcome could have a material adverse effect upon the Company’s consolidated financial position, results of operations or liquidity. The Company does not, however, anticipate such an outcome and it believes the ultimate resolution of these matters will not have a material adverse effect on the Company’s consolidated financial position, results of operations or liquidity.

Long-Term Take-or-Pay Natural Gas Purchase Contracts

The Company has entered into quarterly fixed price natural gas purchase contracts with take-or-pay commitments extending through September 2024. As of December 31, 2023, the fixed commitments under these contracts totaled approximately $13.2 million for the year ending December 31, 2024.

Loan Commitment to an Equity Method Investee

In November 2022, the Company entered into a note purchase agreement with a certain equity method investee (the “Note Purchase Agreement”). Pursuant to the Note Purchase Agreement, the Company irrevocably committed to make available up to $5.5 million in delayed draw loans to fund the investee’s working capital requirements. In exchange, the Company received a convertible promissory note with a principal balance equal to the total amount of drawdown on the loan commitment. The convertible promissory note carries an interest rate equal to 7% per annum, compounded quarterly, and is due and payable in May 2024, subject to certain, specified prepayment clauses. By the end of the third quarter of

2023, the Company had funded a total of $5.5 million in delayed draw loans with respect to the loan commitment; as a result, its commitment pursuant to the Note Purchase Agreement was satisfied.

Revenue from Contracts with Customers - Contract Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Revenue from Contracts with Customers
Accounts receivable, net	$ 98,426	$ 91,430
Contract assets - current	7,823	6,063
Contract assets - non-current	2,433	2,976
Contract assets - total	10,256	9,039
Contract liabilities - current	4,936	5,477
Contract liabilities - non-current	151	0
Contract liabilities - total	5,087	5,477
Station construction sales
Revenue from Contracts with Customers
Contract liabilities - current	4,900	5,500
Contract liabilities - non-current	$ 200	$ 0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Investments in Other Entities and Noncontrolling Interest in a Subsidiary - Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Summarized Financial Information
Net loss	$ (100,098)	$ (59,590)	$ (94,155)
Net income (loss)	(99,497)	(58,733)	(93,146)
Current assets	470,175	471,720
Total assets	1,259,458	1,082,357
Current liabilities	163,823	148,146
Total liabilities	525,811	354,886
Equity attributable to shareholders	726,770	719,993
Equity attributable to noncontrolling interest	6,877	7,478
Total equity	733,647	727,471	755,411	$ 522,850
TotalEnergies
Summarized Financial Information
Revenue	1,462	0	0
Gross profit	173	0	0
Operating income (loss)	(3,414)	(454)	(119)
Net loss	(4,951)	(454)	(119)
Current assets	13,838	11
Non-current assets	33,289	32,773
Total assets	47,127	32,784
Current liabilities	2,518	4,326
Non-current liabilities	29,595	19,493
Total liabilities	32,113	23,819
bpJV
Summarized Financial Information
Revenue	0	0	0
Gross profit	0	0	0
Operating income (loss)	(15,074)	(7,210)	(678)
Net loss	(10,241)	(5,485)	(603)
Net income (loss)	(9,127)	(5,426)	(599)
Current assets	209,973	157,241
Non-current assets	296,240	207,464
Total assets	506,213	364,705
Current liabilities	27,706	22,698
Non-current liabilities	13,558	2,716
Total liabilities	41,264	25,414
Equity attributable to shareholders	440,613	313,544
Equity attributable to noncontrolling interest	24,336	25,747
Total equity	464,949	339,291
SAFE&CEC S.r.l.
Summarized Financial Information
Revenue	97,740	110,104	109,119
Gross profit	24,098	24,902	25,784
Operating income (loss)	(562)	2,513	4,728
Net loss	(2,148)	951	2,392
Current assets	79,981	82,514
Non-current assets	59,636	60,187
Total assets	139,617	142,701
Current liabilities	70,193	73,931
Non-current liabilities	20,888	20,248
Total liabilities	91,081	94,179
Other Equity Method Investments
Summarized Financial Information
Revenue	615	1,217	704
Gross profit	327	506	216
Operating income (loss)	(4,513)	(2,556)	(1,757)
Net loss	(4,539)	(2,585)	$ (1,793)
Current assets	1,436	1,652
Non-current assets	4,281	4,609
Total assets	5,717	6,261
Current liabilities	1,231	1,169
Non-current liabilities	6,312	2,383
Total liabilities	$ 7,543	$ 3,552

Stockholders' Equity - TotalEnergies Private Placement (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jun. 13, 2018	May 09, 2018	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stockholders' equity
Fees and issuance costs			$ 0	$ 0	$ 6,534
Purchase Agreement
Stockholders' equity
Number of shares issued in transaction (in shares)	50,856,296	50,856,296
Price per share (in dollars per share)		$ 1.64
Percentage of ownership after transaction	25.00%
Consideration received on transaction	$ 83,400
Fees and issuance costs	$ 1,900
Purchase Agreement \| Purchase Percentage Covenant, Threshold
Stockholders' equity
Percentage of ownership after transaction		5.00%
Purchase Agreement \| Purchase Percentage Covenant, Maximum
Stockholders' equity
Percentage of ownership after transaction		30.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
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-Section 45
-Paragraph 3
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-URI https://asc.fasb.org//1943274/2147483014/272-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 13
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (b)
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Summary of Significant Accounting Policies - Alternative Fuel Excise Tax Credit (Details) - $ / gal	12 Months Ended		24 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2023
Alternative Fuel Excise Tax Credit
Federal alternative fuels tax credit - CNG (in dollars per gasoline gallon equivalent)	0.50	0.50	0.50
Federal alternative fuels tax credit - LNG (in dollars per liquid gallon)	0.50	0.50	0.50

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash, cash equivalents and current portion of restricted cash	$ 106,963	$ 125,950
Short-term investments	158,186	139,569
Accounts receivable, net of allowance of $1,375 and $1,471 as of December 31, 2022 and September 30, 2023, respectively	98,426	91,430
Other receivables	19,770	17,026
Inventory	45,335	37,144
Prepaid expenses and other current assets	41,495	60,601
Total current assets	470,175	471,720
Operating lease right-of-use assets	92,324	52,586
Land, property and equipment, net	331,758	264,068
Notes receivable and other long-term assets, net	35,735	30,467
Investments in other entities	258,773	193,273
Goodwill	64,328	64,328
Intangible assets, net	6,365	5,915
Total assets	1,259,458	1,082,357
Current liabilities:
Current portion of debt	38	93
Current portion of finance lease obligations	1,758	948
Current portion of operating lease obligations	6,687	4,206
Accounts payable	56,995	44,435
Accrued liabilities	91,534	90,079
Deferred revenue	4,936	5,970
Derivative liabilities, related party	1,875	2,415
Total current liabilities	163,823	148,146
Long-term portion of debt	261,123	145,471
Long-term portion of finance lease obligations	1,839	2,134
Long-term portion of operating lease obligations	89,065	48,911
Long-term portion of derivative liabilities, related party	0	1,430
Other long-term liabilities	9,961	8,794
Total liabilities	525,811	354,886
Commitments and contingencies (Note 17)
Stockholders' equity:
Preferred stock, $0.0001 par value. 1,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.0001 par value. 454,000,000 shares authorized; 222,437,429 shares and 222,987,248 shares issued and outstanding as of December 31, 2022 and September 30, 2023, respectively	22	22
Additional paid-in capital	1,658,339	1,553,668
Accumulated deficit	(929,472)	(829,975)
Accumulated other comprehensive loss	(2,119)	(3,722)
Total Clean Energy Fuels Corp. stockholders' equity	726,770	719,993
Noncontrolling interest in subsidiary	6,877	7,478
Total stockholders' equity	733,647	727,471
Total liabilities and stockholders' equity	$ 1,259,458	$ 1,082,357

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Finance leases:
Depreciation on assets under finance leases	$ 928	$ 877
Interest on lease liabilities	183	164
Total finance leases expense	1,111	1,041
Operating leases:
Lease expense	15,986	8,800
Lease expense on short-term leases	503	513
Variable lease expense	4,777	4,306
Sublease income	(636)	(636)
Total operating leases expense	$ 20,630	$ 12,983

Divestitures - BP Transaction (Details) $ in Thousands			1 Months Ended		12 Months Ended
Divestitures - BP Transaction (Details) $ in Thousands	Mar. 01, 2019 USD ($)	Feb. 27, 2017 USD ($) facility	Dec. 31, 2019 USD ($)	Feb. 28, 2018 USD ($) shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Acquisition and Divestitures
Asset purchase agreement, gain from sale of certain assets of subsidiary					$ 0	$ 0	$ 3,885
Goodwill					64,328	64,328	64,328
BP Products North America, Inc.
Acquisition and Divestitures
Production facilities to be developed \| facility		2
Asset purchase agreement, cash paid	$ 5,400			$ 900
Asset purchase agreement, accrued amount					500	100	900
Asset purchase agreement, gain from sale of certain assets of subsidiary			$ 8,400		4,400	1,000
Asset purchase agreement, contingent consideration (up to)		$ 25,000			3,900	$ 1,100	7,500
Asset purchase agreement, contingent consideration, term		5 years
Asset purchase agreement, payment of transaction costs			$ 2,800	$ 100	$ 10,300		$ 600
Asset purchase agreement, shares issued (in shares) \| shares				15,877	770,269
Asset purchase agreement, shares issued, value				$ 0	$ 2,000
Maximum \| BP Products North America, Inc.
Acquisition and Divestitures
Asset purchase agreement, contingent consideration, term			5 years
Minimum \| BP Products North America, Inc.
Acquisition and Divestitures
Asset purchase agreement, contingent consideration, term			4 years

Other Receivables (Tables)

12 Months Ended

Dec. 31, 2023

Receivables [Abstract]

Schedule of other receivables

Other receivables as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Loans to customers to finance vehicle purchases	$	523	$	194
Accrued customer billings		4,910		5,566
Fuel tax credits		9,462		8,876
Other		2,131		5,134
Total other receivables	$	17,026	$	19,770

Other Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Other Receivables
Other receivables	$ 19,770	$ 17,026
Loans to customers to finance vehicle purchases
Other Receivables
Other receivables	194	523
Accrued customer billings
Other Receivables
Other receivables	5,566	4,910
Fuel tax credits
Other Receivables
Other receivables	8,876	9,462
Other
Other Receivables
Other receivables	$ 5,134	$ 2,131

Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contracts with Customers
Total revenue	$ 425,159	$ 420,164	$ 255,646
Contra revenue charge	60,609	24,302	83,641
Fuel Sales
Revenue from Contracts with Customers
Total revenue	286,956	281,103	130,973
RIN Credits
Revenue from Contracts with Customers
Total revenue	25,860	34,635	31,736
LCFS Credits
Revenue from Contracts with Customers
Total revenue	9,885	12,634	16,808
AFTC
Revenue from Contracts with Customers
Total revenue	20,854	21,760	20,700
Total volume-related product revenue
Revenue from Contracts with Customers
Total revenue	343,397	350,649	196,727
Station construction sales
Revenue from Contracts with Customers
Total revenue	26,427	22,346	16,406
Product revenue
Revenue from Contracts with Customers
Total revenue	369,824	372,995	213,133
Volume-related, O&M services
Revenue from Contracts with Customers
Total revenue	52,660	45,901	41,934
Other services
Revenue from Contracts with Customers
Total revenue	2,675	1,268	579
Service revenue
Revenue from Contracts with Customers
Total revenue	55,335	47,169	42,513
Volume-Related
Revenue from Contracts with Customers
Gain (loss) due to changes in fair value	$ (158)	$ 517	$ (3,490)

Cash, Cash Equivalents and Restricted Cash (Tables)

12 Months Ended

Dec. 31, 2023

Cash and Cash Equivalents [Abstract]

Schedule of cash and cash equivalents

Cash, cash equivalents and restricted cash as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Current assets:
Cash and cash equivalents	$	123,950	$	104,944
Restricted cash - standby letter of credit		2,000		2,019
Total cash, cash equivalents and current portion of restricted cash	$	125,950	$	106,963

Total cash, cash equivalents and restricted cash	$	125,950	$	106,963

Schedule of components of restricted cash

Cash, cash equivalents and restricted cash as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Current assets:
Cash and cash equivalents	$	123,950	$	104,944
Restricted cash - standby letter of credit		2,000		2,019
Total cash, cash equivalents and current portion of restricted cash	$	125,950	$	106,963

Total cash, cash equivalents and restricted cash	$	125,950	$	106,963

Summary of Significant Accounting Policies - Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials and spare parts	$ 45,335	$ 37,144
Total inventory	$ 45,335	$ 37,144

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest in Subsidiary	Total
Beginning balance at Dec. 31, 2020	$ 20	$ 1,191,791	$ (678,096)	$ (209)	$ 9,344	$ 522,850
Beginning balance (in shares) at Dec. 31, 2020	198,491,204
Increase (Decrease) in Stockholders' Equity
Issuance of common stock	$ 2	197,919				197,921
Issuance of common stock (in shares)	24,646,419
Repurchase of common stock		(2,916)				(2,916)
Repurchase of common stock (in shares)	(452,700)
Stock-based compensation		14,994				14,994
Stock-based sales incentive charges		118,130				118,130
Net loss			(93,146)		(1,009)	(94,155)
Other comprehensive income (loss)				(1,413)	0	(1,413)
Ending balance at Dec. 31, 2021	$ 22	1,519,918	(771,242)	(1,622)	8,335	755,411
Ending balance (in shares) at Dec. 31, 2021	222,684,923
Increase (Decrease) in Stockholders' Equity
Issuance of common stock	$ 0	1,365				1,365
Issuance of common stock (in shares)	942,760
Repurchase of common stock	$ 0	(6,122)				(6,122)
Repurchase of common stock (in shares)	(1,190,254)
Stock-based compensation		26,473				26,473
Stock-based sales incentive charges		12,034				12,034
Net loss			(58,733)		(857)	(59,590)
Other comprehensive income (loss)				(2,100)	0	(2,100)
Ending balance at Dec. 31, 2022	$ 22	1,553,668	(829,975)	(3,722)	7,478	$ 727,471
Ending balance (in shares) at Dec. 31, 2022	222,437,429					222,437,429
Increase (Decrease) in Stockholders' Equity
Issuance of common stock	$ 0	685				$ 686
Issuance of common stock (in shares)	589,537
Repurchase of common stock		(175)				$ (175)
Repurchase of common stock (in shares)						0
Stock-based compensation		23,336				$ 23,336
Stock-based sales incentive charges		38,388				38,388
Net loss			(99,497)		(601)	(100,098)
Other comprehensive income (loss)				1,603	0	1,603
Issuance of common stock warrants		42,435				42,435
Ending balance at Dec. 31, 2023	$ 22	$ 1,658,339	$ (929,472)	$ (2,119)	$ 6,877	$ 733,647
Ending balance (in shares) at Dec. 31, 2023	223,026,966					223,026,966

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Leases

Schedule of finance and operating lease asset and liability balances

As of December 31, 2022 and 2023, the Company’s finance and operating lease asset and liability balances were as follows (in thousands):


	2022		2023
Finance leases:
Land, property and equipment, gross	$	5,703	$	6,436
Accumulated depreciation		(2,895)		(3,199)
Land, property and equipment, net	$	2,808	$	3,237

Current portion of finance lease obligations	$	948	$	1,758
Long-term portion of finance lease obligations		2,134		1,839
Total finance lease liabilities	$	3,082	$	3,597

Operating leases:
Operating lease right-of-use assets	$	52,586	$	92,324

Current portion of operating lease obligations	$	4,206	$	6,687
Long-term portion of operating lease obligations		48,911		89,065
Total operating lease liabilities	$	53,117	$	95,752

Schedule of components of lease expense for finance and operating lease liabilities and supplemental information

The components of lease expense for finance and operating leases consisted of the following (in thousands):


	Year Ended December 31,
	2022		2023
Finance leases:
Depreciation on assets under finance leases	$	877	$	928
Interest on lease liabilities		164		183
Total finance leases expense	$	1,041	$	1,111

Operating leases:
Lease expense	$	8,800	$	15,986
Lease expense on short-term leases		513		503
Variable lease expense		4,306		4,777
Sublease income		(636)		(636)
Total operating leases expense	$	12,983	$	20,630

Supplemental information on finance and operating leases is as follows (dollars in thousands):


	Year Ended December 31,
	2022		2023
Operating cash outflows from finance leases	$	164	$	183
Operating cash outflows from operating leases	$	6,582	$	10,709
Financing cash outflows from finance leases	$	945	$	1,055

Assets obtained in exchange for new finance lease liabilities ⁽¹⁾	$	774	$	1,569
ROU assets obtained in exchange for operating lease liabilities ⁽¹⁾	$	13,449	$	46,592


	December 31,	December 31,
	2022	2023
Weighted-average remaining lease term - finance leases	2.34 years	2.44 years
Weighted-average remaining lease term - operating leases	11.29 years	10.14 years

Weighted-average discount rate - finance leases	5.71%	7.41%
Weighted-average discount rate - operating leases	8.44%	9.82%

(1)	These amounts are excluded from the accompanying consolidated statements of cash flows as they are non-cash investing, operating and/or financing activities.

Schedule of maturities of operating lease liabilities

The following schedule presents the Company’s maturities of finance and operating lease liabilities as of December 31, 2023 (in thousands):


Fiscal Year	Finance Leases		Operating Leases
2024	$	1,979	$	15,125
2025		1,073		15,406
2026		593		15,363
2027		362		15,359
2028		3		14,531
Thereafter		—		75,759
Total minimum lease payments		4,010		151,543
Less amount representing interest		(413)		(55,791)
Present value of lease liabilities	$	3,597	$	95,752

Schedule of maturities of finance lease liabilities


Fiscal Year	Finance Leases		Operating Leases
2024	$	1,979	$	15,125
2025		1,073		15,406
2026		593		15,363
2027		362		15,359
2028		3		14,531
Thereafter		—		75,759
Total minimum lease payments		4,010		151,543
Less amount representing interest		(413)		(55,791)
Present value of lease liabilities	$	3,597	$	95,752

Schedule of maturities of lease receivables

The following schedule presents the Company’s maturities of lease receivables as of December 31, 2023 (in thousands):


Fiscal Year:
2024	$	962
2025		962
2026		985
2027		1,105
2028		515
Thereafter		703
Total minimum lease payments		5,232
Less amount representing interest		(1,087)
Present value of lease receivables	$	4,145

401(k) Plan

12 Months Ended

Dec. 31, 2023

Retirement Benefits [Abstract]

401(k) Plan

Note 17 —401(k) Plan

The Company has established a savings plan (“Savings Plan”) which is qualified under Section 401(k) of the Internal Revenue Code. Eligible employees may elect to make contributions to the Savings Plan through salary deferrals of up to 90% of their base pay, subject to Internal Revenue Code limitations. The Company may also make discretionary contributions to the Savings Plans, subject to limitations. For each of the years ended December 31, 2021, 2022 and 2023 the Company contributed approximately $1.6 million, $1.9 million and $1.7 million, respectively, of matching contributions to the Savings Plan.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//715/tableOfContent

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480126/715-20-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (100,098)	$ (59,590)	$ (94,155)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	45,674	54,674	45,184
Provision for credit losses and inventory	1,773	2,035	1,257
Stock-based compensation expense	23,336	26,473	14,994
Stock-based sales incentive charges	60,609	24,302	83,641
Change in fair value of derivative instruments	158	(517)	3,490
Amortization of discount and debt issuance cost	(4,708)	(1,712)	20
Gain on disposal of property and equipment	863	12	1,365
Loss on extinguishment of debt	5,367	3,413	39
Gain from sale of certain assets of subsidiary	0	0	(3,885)
Asset impairments and other charges	634	0	0
Loss from equity method investments	12,510	4,824	430
Non-cash lease expense	6,854	3,400	2,945
Deferred income taxes	(515)	173	69
Expense reimbursement from JV	0	0	1,640
Changes in operating assets and liabilities:
Accounts and other receivables	(7,711)	(1,072)	(24,260)
Inventory	(11,391)	(9,318)	(5,704)
Prepaid expenses and other assets	510	(1,366)	(10,498)
Operating lease liabilities	(3,957)	(3,314)	(3,053)
Accounts payable	14,770	9,324	6,615
Deferred revenue	(883)	(1,281)	4,550
Accrued liabilities and other	(18)	16,271	16,614
Net cash provided by (used in) operating activities	43,777	66,731	41,298
Cash flows from investing activities:
Purchases of short-term investments	(491,253)	(410,027)	(324,170)
Maturities and sales of short-term investments	479,288	401,639	223,991
Purchases of and deposits on property and equipment	(100,934)	(44,518)	(23,075)
Grant proceeds for capital projects	1,947	0	0
Disbursements for loans receivable	(3,500)	(2,310)	(3,905)
Proceeds from paydowns, maturities, and sales of loans receivables	2,256	1,116	421
Cash received from sale of certain assets of subsidiary, net	0	3,885	887
Investments in other entities	(73,450)	(89,700)	(78,919)
Payment and deposits on equipment and manure rights for RNG production projects	(20,348)	(8,986)	(5,830)
Proceeds received for joint development and construction of station projects	3,224	0	0
Advance to DR JV	(5,500)	0	0
Proceeds from repayment of advance by DR JV	5,500	0	0
Proceeds from settlement of insurance claims	495	0	0
Proceeds from disposal of property and equipment	262	360	2,941
Net cash (used in) investing activities	(202,013)	(148,541)	(207,659)
Cash flows from financing activities:
Issuance of common stock	242	1,365	204,455
Repurchase of common stock	0	(6,122)	(2,916)
Payments of tax withholdings on net settlement of equity awards	(175)	0	0
Fees paid for issuance of common stock	0	0	(6,534)
Fees paid for lender and debt issuance costs	(9,484)	(486)	(1,277)
Proceeds for Adopt-a-Port program	955	1,410	5,815
Repayment of proceeds for Adopt-a-Port program	(1,441)	(1,163)	(360)
Proceeds from debt instruments	300,255	159,883	4,400
Proceeds from revolving line of credit	0	1,700	1,450
Repayments of borrowing under revolving line of credit	0	(1,700)	(1,450)
Repayments of debt instruments and finance lease obligations	(151,148)	(49,999)	(50,737)
Payments of debt extinguishment costs	(83)	(3,239)	(14)
Net cash (used in) financing activities	139,121	101,649	152,832
Effect of exchange rates on cash, cash equivalents and restricted cash	128	(345)	8
Net (decrease) in cash, cash equivalents and restricted cash	(18,987)	19,494	(13,521)
Cash, cash equivalents and restricted cash, beginning of period	125,950	106,456	119,977
Cash, cash equivalents and restricted cash, end of period	106,963	125,950	106,456
Supplemental disclosure of cash flow information:
Income taxes paid	77	68	15
Interest paid, net of $0 and $581 capitalized, respectively	$ 16,360	$ 1,873	$ 3,907

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue:
Total revenue	$ 425,159	$ 420,164	$ 255,646
Cost of sales (exclusive of depreciation and amortization shown separately below):
Selling, general and administrative	112,265	109,456	89,906
Depreciation and amortization	45,674	54,674	45,184
Total operating expenses	501,559	471,871	350,694
Operating loss	(76,400)	(51,707)	(95,048)
Interest expense	(22,924)	(6,308)	(4,430)
Interest income	11,148	3,374	1,082
Other income, net	165	95	905
Loss from equity method investments	(12,510)	(4,824)	(430)
Gain from sale of certain assets of subsidiary	0	0	3,885
Loss before income taxes	(100,521)	(59,370)	(94,036)
Income tax (expense) benefit	423	(220)	(119)
Net loss	(100,098)	(59,590)	(94,155)
Loss attributable to noncontrolling interest	601	857	1,009
Net loss attributable to Clean Energy Fuels Corp.	$ (99,497)	$ (58,733)	$ (93,146)
Net loss attributable to Clean Energy Fuels Corp. per share:
Basic (in dollars per share)	$ (0.45)	$ (0.26)	$ (0.44)
Diluted (in dollars per share)	$ (0.45)	$ (0.26)	$ (0.44)
Weighted-average common shares outstanding:
Basic (in shares)	222,904,785	222,414,790	213,118,694
Diluted (in shares)	222,904,785	222,414,790	213,118,694
Product revenue
Revenue:
Total revenue	$ 369,824	$ 372,995	$ 213,133
Cost of sales (exclusive of depreciation and amortization shown separately below):
Cost of sales	309,901	279,748	189,600
Service revenue
Revenue:
Total revenue	55,335	47,169	42,513
Cost of sales (exclusive of depreciation and amortization shown separately below):
Cost of sales	$ 33,719	$ 27,993	$ 26,004

Fair Value Measurements - Other Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	$ 300,255	$ 150,093
Amortized Cost
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	261,161,000
Estimated Fair Value
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	253,558,000
Stonepeak Term Loan
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	300,000
Stonepeak Term Loan \| Amortized Cost
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	260,906,000
Stonepeak Term Loan \| Estimated Fair Value
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	253,303,000
Other debt
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	255	$ 93
Other debt \| Amortized Cost
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	255,000
Other debt \| Estimated Fair Value
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total debt	$ 255,000

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Valuation allowance
Deferred tax assets, valuation allowance	$ 202,242	$ 177,224
Net increase in valuation allowance	25,000
Reconciliation of the total amounts of unrecognized tax benefits
Unrecognized tax benefits, if recognized, fully offset with valuation allowance	59,100
Unrecognized tax benefit at the beginning of the period	54,672	50,585
Gross increases-tax positions in current year	4,517	4,358
Gross decreases-tax positions in prior year	(93)	(271)
Unrecognized tax benefit at the end of the period	59,096	54,672	$ 50,585
Additional information on income tax
Interest expense related to uncertain tax positions	$ 0	$ 0	$ 0

Related Party Transactions

12 Months Ended

Dec. 31, 2023

Related Party Transactions

Note 19 —Related Party Transactions

TotalEnergies S.E.

During the years ended December 31, 2021, 2022 and 2023, the Company recognized revenue of $4.9 million, $7.6 million, and $1.4 million, respectively, relating to RINs and LNG sold to TotalEnergies and its affiliates in the ordinary course of business, equipment lease revenue, AFTCs, and settlements on commodity swap contracts (Note 7). As of December 31, 2022, the Company had receivables from TotalEnergies of $2.5 million. Outstanding receivables due from TotalEnergies were immaterial as of December 31, 2023.

During the years ended December 31, 2021, 2022 and 2023, the Company paid TotalEnergies $2.0 million, $8.4 million, and $6.9 million, respectively, for expenses incurred in the ordinary course of business, settlements on commodity swap contracts (Note 7), and the guaranty fee under the Credit Support Agreement with TotalEnergies Holdings USA Inc., a wholly owned subsidiary of TotalEnergies. As of December 31, 2022, outstanding payables due to TotalEnergies were $0.2 million. Outstanding payables due to TotalEnergies were immaterial as of December 31, 2023.

SAFE&CEC S.r.l

During the years ended December 31, 2021, 2022 and 2023, the Company received $0.2 million, $0.2 million, and $0.3 million, respectively, from SAFE&CEC S.r.l. in the ordinary course of business. As of December 31, 2022 and 2023, the Company had receivables due from SAFE&CEC S.r.l. of $0.3 million and $0.3 million, respectively.

During the years ended December 31, 2021, 2022 and 2023, the Company paid SAFE&CEC S.r.l $9.6 million, $16.7 million, and $12.6 million, respectively, for parts and equipment in the ordinary course of business. As of December 31, 2022 and 2023, the Company had payables due to SAFE&CEC S.r.l. of $3.3 million and $8.1 million, respectively.

TotalEnergies Joint Venture(s) and bpJV

Pursuant to various contractual agreements of the TotalEnergies joint venture(s) and bpJV, the Company manages day-to-day operations of RNG projects in the joint ventures in exchange for an O&M fee and management fee. For the years ended December 31, 2021, 2022 and 2023, the Company recognized management and O&M fee revenue of $0.4 million, $1.3 million, and $3.1 million, respectively. As of December 31, 2022 and 2023, the Company had management and O&M fee receivables due from the joint ventures with TotalEnergies and bp of $0.5 million and $0.3 million, respectively.

For the years ended December 31, 2021, 2022 and 2023, the Company paid $0.0 million, $0.6 million, and $1.2 million, respectively, on behalf of the joint ventures for expenses incurred in the ordinary course of business. As of December 31, 2022 and 2023, outstanding receivables due from the joint ventures with TotalEnergies and bp totaled $0.6

million and $0.7 million, respectively, representing outstanding unreimbursed expenses that the Company paid on behalf of the joint ventures.

For the years ended December 31, 2021, 2022 and 2023, the Company received $0.0 million, $1.5 million, and $5.0 million, respectively, from the joint ventures with TotalEnergies and bp for management and O&M fees and reimbursement of expenses incurred in the ordinary course of business. No amounts were paid to the joint ventures with TotalEnergies and bp for the years ended December 30, 2021, 2022 and 2023. As of December 31, 2023, the Company had payables due to the joint ventures with TotalEnergies and bp of $0.6 million relating to sharing of environmental credits pursuant to the various contractual agreements of the TotalEnergies joint venture(s) and bpJV. As of December 31, 2022, no payables were outstanding relating to sharing of environmental credits.

In connection with the capital call issued by the DR JV on June 28, 2023, the Company advanced $5.5 million to the DR JV. Proceeds from the advance were used to fund required loan reserves and to paydown outstanding liabilities of the DR JV (see Note 4). In December 2023, the $5.5 million advance was refunded to the Company by the DR JV.

Other Equity Method Investees

For the years ended December 31, 2022 and 2023, the Company provided $2.0 million and $3.5 million, respectively, to a certain equity method investee pursuant to the Note Purchase Agreement (see Note 15). As of December 31, 2022 and 2023, the carrying amount of the Company’s convertible promissory note measured at fair value was $1.9 million and $2.3 million, respectively, and is included in “Notes receivable and other long-term assets, net” as of December 31, 2022 and in “Other receivables” as of December 31, 2023 in the accompanying consolidated balance sheets.

For the years ended December 31, 2022 and 2023, the Company recognized management fee revenue of $0.1 million and $0.6 million, respectively, from the Company’s other equity method investees. No management fee revenue was recognized for the year ended December 31, 2021. As of December 31, 2022 and 2023, the Company had management fee receivables due from other equity method investees of $0.1 million and $0.7 million, respectively.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

+ Details

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Cash Flows [Abstract]
Capitalized interest paid, respectively	$ 2,587	$ 0	$ 0

Investments in Other Entities and Noncontrolling Interest in a Subsidiary - TotalEnergies Joint Venture (Details) - USD ($) $ in Thousands			1 Months Ended	12 Months Ended
	Jun. 28, 2023	Nov. 01, 2021	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 27, 2023	Oct. 12, 2021	Mar. 03, 2021
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments				$ (12,510)	$ (4,824)	$ (430)
Advance to DR JV				5,500	0	0
TotalEnergies
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments				(2,500)	(200)	$ (100)
Investment balance			$ 7,500	$ 7,500	$ 4,500
TotalEnergies \| ADG RNG Production Facilities
Schedule of Equity Method Investments [Line Items]
Investment commitment of equity in production projects									$ 400,000
Investment commitment in joint venture									50,000
TotalEnergies \| ADG RNG Production Facilities \| TotalEnergies S.E.
Schedule of Equity Method Investments [Line Items]
Investment commitment in joint venture									$ 50,000
TotalEnergies \| DR Development Agreement
Schedule of Equity Method Investments [Line Items]
Investment commitment in joint venture							$ 5,500	$ 7,000
Initial contribution commitment		$ 4,800
Capital call contribution amount							$ 11,000
Contribution to joint venture	$ 5,500
Advance to DR JV	$ 5,500
Advance amount expected to refund			$ 5,500
TotalEnergies \| DR Development Agreement \| TotalEnergies S.E.
Schedule of Equity Method Investments [Line Items]
Investment commitment in joint venture								$ 7,000
Initial contribution commitment		$ 4,800

Short-Term Investments

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

Note 6 —Short-Term Investments

Short-term investments include available-for-sale debt securities, excluded from cash equivalents, that have maturities of one year or less on the date of acquisition and certificates of deposit. Available-for-sale debt securities are carried at fair value, inclusive of unrealized gains and losses. Unrealized gains and losses on available for sale debt securities are recognized in other comprehensive income (loss), net of applicable income taxes. Gains or losses on sales of available-for-sale debt securities are recognized on the specific identification basis.

The Company reviews available-for-sale debt securities for declines in fair value below their cost basis each quarter and whenever events or changes in circumstances indicate that the cost basis of an asset may not be recoverable, and evaluates the current expected credit loss. This evaluation is based on a number of factors, including historical experience, market data, issuer-specific factors, economic conditions, and any changes to the credit rating of the security. As of December 31, 2023, the Company has not recorded a credit loss related to available-for-sale debt securities and believes the carrying values for its available-for-sale debt securities are properly recorded.

Short-term investments as of December 31, 2022 consisted of the following (in thousands):


			Gross
	Amortized		Unrealized		Estimated
	Cost		Gain (Loss)		Fair Value
Zero coupon bonds	$	74,524	$	(365)	$	74,159
U.S. government securities		64,861		19		64,880
Certificates of deposit		530		—		530
Total short-term investments	$	139,915	$	(346)	$	139,569

Short-term investments as of December 31, 2023 consisted of the following (in thousands):


			Gross
	Amortized		Unrealized		Estimated
	Cost		Gain (Loss)		Fair Value
U.S. government securities	$	157,628	$	28	$	157,656
Certificates of deposit		530		—		530
Total short-term investments	$	158,158	$	28	$	158,186

Stockholders' Equity - Stock Based Compensation (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-based compensation
Stock-based compensation expense, net of $0 tax in 2019, 2020, and 2021		$ 23,336	$ 26,473	$ 14,994
Stock-based compensation expense, tax		$ 0	$ 0	$ 0
Amended 2016 Plan
Stock-based compensation
Increase in the aggregate number of shares	17,500,000
Number of shares available for future grant		6,250,580

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 2
-Subparagraph (a)(3)
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Paragraph 2
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Section 50
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-Subparagraph (c)(1)(iii)
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (c)(1)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Paragraph 2
-Subparagraph (c)(1)(iv)(02)
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(03)
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Section 50
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2003/role/disclosureRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Paragraph 2
-Subparagraph (e)(2)
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
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-Subparagraph (f)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Reportable Segments and Geographic Information

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Reportable Segments and Geographic Information

Note 20 —Reportable Segments and Geographic Information

Disclosures are required for certain information regarding operating segments, products and services, geographic areas of operation and major customers. Segment reporting is based on the “management approach,” which assesses, how management organizes the Company’s operating segments for which separate financial information is (1) available and (2) evaluated regularly by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources and in assessing performance. The Company’s CODM is its Chief Executive Officer.

The Company operates in a single segment to supply natural gas. In making operating decisions, the CODM primarily considers consolidated financial information, accompanied by fuel and O&M services volume information. The assessment of operating results and the allocation of resources among the components of the business are made by the CODM and are based on profitability margins and volumes by market sector and by type. Contracts are evaluated based on the economics of a mix of products and services for a customer.

The table below presents the Company’s revenue, operating loss and long-lived assets by geographic area (in thousands). Several of the Company’s functions, including marketing, engineering, and finance are performed at the corporate level. As a result, significant interdependence and overlap exist among the Company’s geographic areas. Geographic revenue data reflect internal allocations and are therefore subject to certain assumptions and the Company’s methodology. Accordingly, revenue, operating loss, and long-lived assets shown for each geographic area may not be the amounts that would have been reported if the geographic areas were independent of one another. Revenue by geographic area is categorized based on where services are rendered and finished goods are sold. Operating loss by geographic area

is categorized based on the location of the entity selling the finished goods or providing the services. Long-lived assets by geographic area are categorized based on the location of the assets.


	2021		2022		2023
Revenue:
United States	$	252,310	$	416,975	$	418,754
Canada		3,336		3,189		6,405
Total revenue	$	255,646	$	420,164	$	425,159
Operating loss:
United States	$	(94,157)	$	(50,796)	$	(75,163)
Canada		(891)		(911)		(1,237)
Total operating loss	$	(95,048)	$	(51,707)	$	(76,400)
Long-lived assets:
United States	$	440,770	$	525,682	$	657,397
Canada		630		1,902		3,827
Total long-lived assets	$	441,400	$	527,584	$	661,224

The Company’s goodwill and intangible assets as of December 31, 2021, 2022 and 2023 relate to its U.S. operations, and its subsidiaries, Clean Energy Cryogenics, Clean Energy Renewable Development, and NG Advantage (see Note 4).

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//280/tableOfContent

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-26

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-34

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

+ Details

Fair Value Measurements - Convertible Promissory Note (Details) - Convertible promissory note	Dec. 31, 2023	Dec. 31, 2022
Fair Value Measurements
Interest rate	7.00%
Risk-free interest rate
Fair Value Measurements
Convertible Promissory Note, Measurement Inputs	5.39	4.57
Credit adjustment
Fair Value Measurements
Convertible Promissory Note, Measurement Inputs	5.31	8.36
Credit adjusted discount rate
Fair Value Measurements
Convertible Promissory Note, Measurement Inputs	10.70	12.93

Investments in Other Entities and Noncontrolling Interest in a Subsidiary (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of Equity Method Investments [Line Items]

Summary of financial information


	Year Ended December 31,
	2021		2022		2023
Revenue	$	704	$	1,217	$	615
Gross profit		216		506		327
Operating loss		(1,757)		(2,556)		(4,513)
Net loss	$	(1,793)	$	(2,585)	$	(4,539)


	As of December 31,
	2022		2023
Current assets	$	1,652	$	1,436
Non-current assets		4,609		4,281
Total assets	$	6,261	$	5,717

Current liabilities	$	1,169	$	1,231
Non-current liabilities		2,383		6,312
Total liabilities	$	3,552	$	7,543

TotalEnergies

Schedule of Equity Method Investments [Line Items]

Summary of financial information

The following table presents the combined summarized financial information of the TotalEnergies joint venture (in thousands):


	Year Ended December 31,
	2021		2022		2023
Revenue	$	—	$	—	$	1,462
Gross profit		—		—		173
Operating loss		(119)		(454)		(3,414)
Net loss	$	(119)	$	(454)	$	(4,951)


	As of December 31,
	2022		2023
Current assets	$	11	$	13,838
Non-current assets		32,773		33,289
Total assets	$	32,784	$	47,127

Current liabilities	$	4,326	$	2,518
Non-current liabilities		19,493		29,595
Total liabilities	$	23,819	$	32,113

bpJV

Schedule of Equity Method Investments [Line Items]

Summary of financial information


	Year Ended December 31,
	2021		2022		2023
Revenue	$	—	$	—	$	—
Gross profit		—		—		—
Operating loss		(678)		(7,210)		(15,074)
Net loss		(603)		(5,485)		(10,241)
Net loss attributable to bpJV	$	(599)	$	(5,426)	$	(9,127)

			As of December 31,
			2022		2023
Current assets			$	157,241	$	209,973
Non-current assets				207,464		296,240
Total assets			$	364,705	$	506,213

Current liabilities			$	22,698	$	27,706
Non-current liabilities				2,716		13,558
Total liabilities			$	25,414	$	41,264

Equity attributable to shareowners of bpJV			$	313,544	$	440,613
Equity attributable to noncontrolling interest				25,747		24,336
Total equity			$	339,291	$	464,949

SAFE&CEC S.r.l.

Schedule of Equity Method Investments [Line Items]

Summary of financial information


	Year Ended December 31,
	2021		2022		2023
Revenue	$	109,119	$	110,104	$	97,740
Gross profit		25,784		24,902		24,098
Operating income		4,728		2,513		(562)
Net income (loss)	$	2,392	$	951	$	(2,148)


	As of December 31,
	2022		2023
Current assets	$	82,514	$	79,981
Non-current assets		60,187		59,636
Total assets	$	142,701	$	139,617

Current liabilities	$	73,931	$	70,193
Non-current liabilities		20,248		20,888
Total liabilities	$	94,179	$	91,081

Fair Value Measurements - Fair Value Recognition - Assets (Details) - USD ($) $ in Thousands	12 Months Ended			24 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Reconciliation of the beginning and ending balances of assets measured at fair value using significant unobservable inputs (Level 3)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue from Contract with Customer, Excluding Assessed Tax	Revenue from Contract with Customer, Excluding Assessed Tax
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income [Extensible List]				Revenue from Contract with Customer, Excluding Assessed Tax
Change in unrealized gain (loss) included in other comprehensive income (loss)	$ 342	$ (327)	$ (19)
Embedded derivatives
Reconciliation of the beginning and ending balances of assets measured at fair value using significant unobservable inputs (Level 3)
Beginning balance	(6,755)	(6,776)		$ (6,776)
Total gain (loss)		(21)
Ending balance	(4,628)	(6,755)	$ (6,776)	(4,628)
Change in unrealized gain (loss) included in earnings	(2,127)	(21)
Convertible promissory note
Reconciliation of the beginning and ending balances of assets measured at fair value using significant unobservable inputs (Level 3)
Beginning balance	(1,880)
Total gain (loss)		(134)
Purchases	3,822	2,014
Equity method investment loss	(3,475)
Ending balance	(2,330)	(1,880)		$ (2,330)
Change in unrealized gain (loss) included in earnings	$ 103
Change in unrealized gain (loss) included in other comprehensive income (loss)		$ (134)

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ (99,497)	$ (58,733)	$ (93,146)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-28

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482765/220-10-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-8

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-9

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-4

Reference 13: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480167/946-830-55-10

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483581/946-220-45-7

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(9))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(1)(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-3

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 20: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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Reference 23: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
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-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Subparagraph (SX 210.13-02(a)(4)(iv))
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-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (a)
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-URI https://asc.fasb.org//1943274/2147482689/260-10-45-60B

Reference 32: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
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Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 34: http://www.xbrl.org/2003/role/disclosureRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483499/205-20-50-7

Reference 35: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1A

Reference 37: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-1B

Reference 38: http://fasb.org/us-gaap/role/ref/legacyRef
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-Paragraph 2
-Subparagraph (SX 210.5-03(20))
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-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 39: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Shareholders' Equity - Amazon Warrant (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
	Apr. 16, 2021	Jun. 30, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 14, 2021	Apr. 15, 2021
Subsidiary, Sale of Stock [Line Items]
Contra revenue charge			$ 60,609	$ 24,302	$ 83,641
Amazon Warrant \| Maximum
Subsidiary, Sale of Stock [Line Items]
Percentage of common stock outstanding owned (as a percent)	4.999%
Amazon Warrant
Subsidiary, Sale of Stock [Line Items]
Aggregate number of warrant shares (in shares)	53,141,755					5,625,959
Total discretionary fuel purchases	$ 500,000
Exercise price of the warrant (in dollars per share)	$ 13.49					$ 13.49
Exercise price premium (as a percent)	21.30%
Common stock price (in dollars per share)							$ 11.12
Aggregate number of warrant shares that may require stockholder approval (in shares)	50,595,531
Notification period to waive or modify Beneficial Ownership Limitation	61 days
Contra revenue charge			60,600	24,300	$ 83,600
Customer incentive assets		$ 38,400
Amazon Warrant \| Prepaid expenses and other current assets
Subsidiary, Sale of Stock [Line Items]
Customer incentive assets				$ 22,200
Amazon Warrant \| Vesting over the first year
Subsidiary, Sale of Stock [Line Items]
Contra revenue charge		$ 76,600	76,600
Amazon Warrant \| Vesting over the second year
Subsidiary, Sale of Stock [Line Items]
Contra revenue charge			$ 7,000

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of loss before income taxes
U.S.	$ (99,749)	$ (58,431)	$ (93,117)
Foreign	(772)	(939)	(919)
Loss before income taxes	(100,521)	(59,370)	(94,036)
Current:
State	92	47	54
Foreign			(4)
Total current	92	47	50
Deferred:
Federal	(318)	78	18
State	(197)	95	51
Total deferred	(515)	173	69
Total tax expense	$ (423)	$ 220	$ 119
Federal income tax rate	21.00%	21.00%	21.00%
Reconciliation of the income tax provision
Computed expected tax (benefit)	$ (21,110)	$ (12,468)	$ (19,747)
Nondeductible expenses	1,062	4,218	617
Tax rate differential on foreign earnings	162	197	189
Joint ventures	1,035	441	(2)
Amazon warrants	5,381	1,134	3,707
Tax credits	(6,250)	(6,065)	(5,299)
Other	(48)	843	1,463
Change in valuation allowance	19,345	11,920	19,191
Total tax expense	(423)	220	119
Tax benefit related to exclusion of AFTC	6,200	5,800	$ 4,900
Deferred tax assets:
Accrued expenses	6,178	5,445
Lease obligations	25,574	14,093
Alternative minimum tax and general business credits	7,011	7,011
Stock option expense	11,756	7,850
Amazon warrants	20,002	16,169
Other	6,096	3,163
Depreciation and amortization	4,270	3,455
Loss carryforwards	152,310	141,381
Total deferred tax assets	233,197	198,567
Less valuation allowance	(202,242)	(177,224)
Net deferred tax assets	30,955	21,343
Deferred tax liabilities:
Right-of-use assets	(24,650)	(13,950)
Commodity swap contracts	(741)	(784)
Goodwill	(3,160)	(2,847)
Investments in joint ventures and partnerships	(2,989)	(4,862)
Total deferred tax liabilities	(31,540)	(22,443)
Net deferred tax liabilities	$ (585)	$ (1,100)

Other Receivables

12 Months Ended

Dec. 31, 2023

Receivables [Abstract]

Other Receivables

Note 9 —Other Receivables

Other receivables as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Loans to customers to finance vehicle purchases	$	523	$	194
Accrued customer billings		4,910		5,566
Fuel tax credits		9,462		8,876
Other		2,131		5,134
Total other receivables	$	17,026	$	19,770

Net Income (Loss) Per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Net Loss Per Share

Note 18 —Net Loss Per Share

The following table sets forth the computations of basic and diluted earnings (loss) per share for the years ended December 31, 2021, 2022 and 2023 (in thousands, except share and per share amounts):


	2021		2022		2023
Net loss attributable to Clean Energy Fuels Corp.	$	(93,146)	$	(58,733)	$	(99,497)

Weighted-average common shares outstanding		213,118,694		222,414,790		222,904,785
Dilutive effect of potential common shares from restricted stock units, stock options and stock warrants		—		—		—
Weighted-average common shares outstanding - diluted		213,118,694		222,414,790		222,904,785
Basic loss per share	$	(0.44)	$	(0.26)	$	(0.45)
Diluted loss per share	$	(0.44)	$	(0.26)	$	(0.45)

The following potentially dilutive securities have been excluded from the diluted net loss per share calculations because their effect would have been antidilutive. Although these securities were antidilutive for these periods, they could be dilutive in future periods.


(in shares)	2021	2022	2023
Stock options	17,153,671	15,456,340	17,825,577
Stonepeak warrant shares	—	—	20,000,000
Restricted stock units	1,126,942	694,945	399,709
Amazon warrant shares	58,767,714	58,767,714	58,767,714
Total	77,048,327	74,918,999	96,993,000

Income Taxes - Tax Credit Carryforwards (Details) $ in Millions	Dec. 31, 2023 USD ($)
Federal
Income Taxes
Operating loss carryforwards	$ 589.7
Federal \| General
Income Taxes
Tax credit carryforwards	8.2
State
Income Taxes
Operating loss carryforwards	460.3
Foreign
Income Taxes
Operating loss carryforwards	$ 4.5

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Principal Balances
Total debt	$ 300,255	$ 150,093
Less amounts due within one year	(38)	(93)
Total long-term debt	300,217	150,000
Unamortized Debt Financing Costs
Total debt	39,094	4,529
Total long-term debt	39,094	4,529
Balance, Net of Financing Costs
Total debt	261,161	145,564
Less amounts due within one year	(38)	(93)
Total long-term debt	261,123	145,471
Riverstone Term Loan
Principal Balances
Total debt		150,000
Unamortized Debt Financing Costs
Total debt		4,529
Balance, Net of Financing Costs
Total debt		145,471
Stonepeak Term Loan
Principal Balances
Total debt	300,000
Unamortized Debt Financing Costs
Total debt	39,094
Balance, Net of Financing Costs
Total debt	260,906
Other debt
Principal Balances
Total debt	255	93
Balance, Net of Financing Costs
Total debt	$ 255	$ 93

Leases - Maturities of Lease Receivables (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Fiscal year:
2024	$ 962
2025	962
2026	985
2027	1,105
2027	515
Thereafter	703
Total minimum lease payments	5,232
Less amount representing interest	(1,087)
Present value of lease receivables	$ 4,145

Investments in Other Entities and Noncontrolling Interest in a Subsidiary - Other Equity Method Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ (12,510)	$ (4,824)	$ (430)
Other Equity Method Investment
Schedule of Equity Method Investments [Line Items]
Investment balance	1,800	2,200
Income (loss) from equity method investments	$ (3,900)	$ (1,200)	$ (600)

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

Note 14 —Income Taxes

The components of loss before income taxes for the years ended December 31, 2021, 2022 and 2023 are as follows (in thousands):


	2021		2022		2023
U.S.	$	(93,117)	$	(58,431)	$	(99,749)
Foreign		(919)		(939)		(772)
Total loss before income taxes	$	(94,036)	$	(59,370)	$	(100,521)

The provision for income taxes for the years ended December 31, 2021, 2022 and 2023 consists of the following (in thousands):


	2021		2022		2023
Current:
State	$	54	$	47	$	92
Foreign		(4)		—		—
Total current		50		47		92
Deferred:
Federal		18		78		(318)
State		51		95		(197)
Total deferred		69		173		(515)
Total expense	$	119	$	220	$	(423)

A reconciliation of the income tax expense for the years ended December 31, 2021, 2022 and 2023, with the amount computed using the federal income tax rate of 21% as of December 31, 2021, 2022 and 2023, consists of the following (in thousands):


	2021		2022		2023
Computed expected tax (benefit)	$	(19,747)	$	(12,468)	$	(21,110)
Nondeductible expenses		617		4,218		1,062
Tax rate differential on foreign earnings		189		197		162
Joint ventures		(2)		441		1,035
Amazon warrants		3,707		1,134		5,381
Tax credits		(5,299)		(6,065)		(6,250)
Other		1,463		843		(48)
Change in valuation allowance		19,191		11,920		19,345
Total tax expense	$	119	$	220	$	(423)

The Company recorded a federal tax benefit of $4.9 million, $5.8 million and $6.2 million related to the exclusion of AFTC associated with 2021, 2022 and 2023 fuel sales in excess of its fuel tax obligation, respectively. These amounts increased the Company’s deferred tax asset and the Company’s deferred tax asset valuation allowance.

Deferred tax assets and liabilities result from differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities. The tax effect of temporary differences that give rise to deferred tax assets and liabilities as of December 31, 2022 and 2023 are as follows (in thousands):


	2022		2023
Deferred tax assets:
Accrued expenses	$	5,445	$	6,178
Lease obligations		14,093		25,574
Alternative minimum tax and general business credits		7,011		7,011
Stock option expense		7,850		11,756
Amazon warrants		16,169		20,002
Other		3,163		6,096
Depreciation and amortization		3,455		4,270
Loss carryforwards		141,381		152,310
Total deferred tax assets		198,567		233,197
Less valuation allowance		(177,224)		(202,242)
Net deferred tax assets		21,343		30,955
Deferred tax liabilities:
Right-of-use assets		(13,950)		(24,650)
Commodity swap contracts		(784)		(741)
Goodwill		(2,847)		(3,160)
Investments in joint ventures and partnerships		(4,862)		(2,989)
Total deferred tax liabilities		(22,443)		(31,540)
Net deferred tax liabilities	$	(1,100)	$	(585)

As of December 31, 2023, the Company had federal, state and foreign net operating loss carryforwards of approximately $589.7 million, $460.3 million and $4.5 million, respectively. The Company’s federal, state and foreign net operating loss carryforwards will, if not utilized, expire beginning in 2027, 2028 and 2033, respectively. The Company also has federal tax credit carryforwards of $8.2 million that will expire beginning in 2026. Due to the change of ownership provisions of Internal Revenue Code Section 382, utilization of a portion of the Company’s net operating loss and tax credit carryforwards may be limited in future periods.

In assessing the realizability of the net deferred tax assets, management considers whether it is more likely than not that some or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers projected future taxable income and tax planning strategies in making this assessment. As of December 31, 2022 and 2023, the Company provided a valuation allowance of $177.2 million and $202.2 million, respectively, to reduce the net deferred tax assets due to uncertainty surrounding the realizability of these assets. The increase in the valuation allowance for the year ended December 31, 2023 of $25.0 million was primarily attributable to an increase in losses without benefit.

For the year ended December 31, 2023, the Company did not have any offshore earnings of certain non-U.S. subsidiaries which are permanently reinvested outside the United States.

The Company does not recognize the impact of a tax position in its financial statements unless the position is more likely than not to be sustained, based on the technical merits of the position. The Company has unrecognized tax benefits of $59.1 million as of December 31, 2023 that, if recognized, would not result in a tax benefit since it would be fully offset with a valuation allowance.

The following is a tabular reconciliation of the total amounts of unrecognized tax benefits for the years ended December 31, 2021, 2022 and 2023 (in thousands):


Unrecognized tax benefit—December 31, 2021	$	50,585
Gross increases—tax positions in current year		4,358
Gross increases—tax positions in prior year		—
Gross decreases—tax positions in prior year		(271)
Unrecognized tax benefit—December 31, 2022		54,672
Gross increases—tax positions in current year		4,517
Gross increases—tax positions in prior year		—
Gross decreases—tax positions in prior year		(93)
Unrecognized tax benefit—December 31, 2023	$	59,096

The increase in the Company’s unrecognized tax benefits in the years ended December 31, 2023 and December 31, 2022 is primarily attributable to the portion of AFTC offset by the fuel tax the Company collected from its customers and the warrants issued to its customer.

ASC 740, Income Taxes, requires the Company to accrue interest and penalties where there is an underpayment of taxes based on the Company’s best estimate of the amount ultimately to be paid. The Company’s policy is to recognize interest accrued related to unrecognized tax benefits and penalties as income tax expense. The Company recognized interest and penalties related to uncertain tax positions of $0.0 million for each of the years ended December 31, 2021, 2022 and 2023.

The Company is subject to taxation in the United States and various states and foreign jurisdictions. The Company’s tax years from 2019 to 2023 are subject to examination by various tax authorities. Although the Company is no longer subject to U.S. examination for years before 2020 and to state tax examinations for years before 2019, taxing authorities can adjust the net operating losses that arose in earlier years if and when the net operating losses reduce future income. In addition, the Company is required to indemnify SAFE&CEC S.r.l. for taxes that are imposed on CEC for pre-contribution tax periods.

A number of years may elapse before an uncertain tax position is finally resolved. It is often difficult to predict the final outcome or the timing of resolution of an uncertain tax position, but the Company believes that its reserves for income taxes reflect the most probable outcomes. The Company adjusts the reserve, as well as the related interest and penalties, in light of changing facts and circumstances. The amount of penalties accrued is immaterial. Settlement of any particular position would usually require the use of cash and result in the reduction of the related reserve, or there could be a change in the amount of the Company’s net operating loss. The resolution of a matter would be recognized as an adjustment to the provision for income taxes at the effective tax rate in the period of resolution. The Company does not expect a significant increase or decrease in its uncertain tax positions within the next twelve months.

On August 16, 2022, the Inflation Reduction Act of 2022 ("the IRA”) was signed into law. Besides the reinstatement of AFTC for the three year period from January 1, 2022 to December 31, 2024, the IRA offers tax incentives targeting energy transaction and renewables:

●

The investment tax credit under Section 48 of the Internal Revenue Code is expanded to include Qualified Biogas Property, which is expected to be available for the RNG dairy projects that the Company has invested or will invest. The investment tax credit rate could range from 6% up to a 50% bonus rate depending on meeting certain wage, apprenticeship, domestic content, and energy community requirements.

●

A new tax credit under Section 45Z of the Internal Revenue Code was introduced to apply to low-emissions transportation fuel produced at a qualified facility and sold by the taxpayer after December 31, 2024 through December 31, 2027. The IRA provides a base credit of 20 cents per gallon or $1.00 per gallon multiplied by an

applicable emission factor if prevailing wage and apprentices requirements are met. The Company expects its RNG dairy projects will be eligible for this credit, although the rate of the credit per gallon is still pending further guidance from the US Treasury department.

●

The alternative fuel refueling property credit under Section 30C of the Internal Revenue Code was reinstated for 2022 and extended an additional 10 years to apply to any property placed in service before January 1, 2033. The base credit amount is 6% with a bonus rate of 30% if wage and registered apprenticeship requirements are met with a maximum credit amount of $100,000 (previously $30,000) per single refueling pump.

The Internal Revenue Service has been granted broad authority to issue regulations or other guidance that could clarify how these taxes will be applied and credits will be eligible. The Company is continuing to evaluate the financial impact of the IRA as additional information becomes available. For the year ended December 31, 2023, two RNG projects that the Company invested in were placed in service and are eligible for the Investment Tax Credits. The Company intends to monetize the tax credits by transferring to third parties.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 21
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-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
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-Paragraph 1
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-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 17
-Subparagraph (b)
-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 10
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-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Related Party Transactions (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended			36 Months Ended
	Jun. 28, 2023	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Related Party Transaction [Line Items]
Advance to DR JV			$ 5,500	$ 0	$ 0
Proceeds from repayment of advance by DR JV			5,500	0	0
Receivables from related party				2,500
Outstanding balance		$ 261,161	261,161	145,564		$ 261,161
Related Party \| TOTALEnergies S.E.
Related Party Transaction [Line Items]
Proceeds from related party			1,400	7,600	4,900
Related party expense			6,900	8,400	2,000
Payable to related parties				200
Related Party \| SAFE&CEC S.r.l.
Related Party Transaction [Line Items]
Proceeds from related party			300	200	200
Receivables from related party		300	300	300		300
Related party expense			12,600	16,700	9,600
Payable to related parties		8,100	8,100	3,300		8,100
Related Party \| TotalEnergies JV and bpJV
Related Party Transaction [Line Items]
Related party expense			1,200	600	0
Related Party \| DR JV
Related Party Transaction [Line Items]
Advance to DR JV	$ 5,500
Proceeds from repayment of advance by DR JV		5,500
Related Party \| Management Fee for Services \| TotalEnergies JV and bpJV
Related Party Transaction [Line Items]
Proceeds from related party			3,100	1,300	400
Receivables from related party		300	300	500		300
Related Party \| Business Expenses Reimbursement \| TotalEnergies JV and bpJV
Related Party Transaction [Line Items]
Receivables from related party		700	700	600		700
Related party expense						0
Related Party \| Management Fee for Services & Business Expenses Reimbursement \| TotalEnergies JV and bpJV
Related Party Transaction [Line Items]
Proceeds from related party			5,000	1,500	0
Related Party \| Sharing of Environmental Credits \| TotalEnergies JV and bpJV
Related Party Transaction [Line Items]
Payable to related parties		600	600	0		600
Other Equity Method Investees
Related Party Transaction [Line Items]
Receivables from related party		700	700	100		700
Amount provided for funding in certain equity method investee			3,500	2,000
Other Equity Method Investees \| Convertible promissory note
Related Party Transaction [Line Items]
Outstanding balance		$ 2,300	2,300	1,900		$ 2,300
Other Equity Method Investees \| Management Fee for Services
Related Party Transaction [Line Items]
Proceeds from related party			$ 600	$ 100	$ 0

Derivative Instruments and Hedging Activities

12 Months Ended

Dec. 31, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities

Note 7 —Derivative Instruments and Hedging Activities

In October 2018, the Company executed two commodity swap contracts with TotalEnergies Gas & Power North America, an affiliate of TotalEnergies, for a total of 5.0 million diesel gallons annually from April 1, 2019 to June 30, 2024. These commodity swap contracts are used to manage diesel price fluctuation risks related to the natural gas fuel supply commitments the Company makes in its fueling agreements with fleet operators that participate in the Zero Now truck financing program. These contracts are not designated as accounting hedges and as a result, changes in the fair value of these derivative instruments are recognized in “Product revenue” in the accompanying consolidated statements of operations.

The Company has entered into fueling agreements with fleet operators under the Zero Now truck financing program. Certain of these fueling agreements contain a pricing feature indexed to diesel, which the Company determined to be an embedded derivative and is recorded at fair value at the time of execution, with the changes in fair value of the embedded derivative recognized in “Product revenue” in the accompanying consolidated statements of operations.

Commodity swaps and embedded derivatives as of December 31, 2022 consisted of the following (in thousands):


	Gross Amounts		Gross Amounts		Net Amount
	Recognized		Offset		Presented
Assets:
Fueling agreements:
Prepaid expenses and other current assets	$	1,640	$	—	$	1,640
Notes receivable and other long-term assets, net		5,115		—		5,115
Total derivative assets	$	6,755	$	—	$	6,755
Liabilities:
Commodity swaps:
Current portion of derivative liabilities, related party	$	2,415	$	—	$	2,415
Long-term portion of derivative liabilities, related party		1,430		—		1,430
Total derivative liabilities	$	3,845	$	—	$	3,845

Commodity swaps and embedded derivatives as of December 31, 2023 consisted of the following (in thousands):


	Gross Amounts		Gross Amounts		Net Amount
	Recognized		Offset		Presented
Assets:
Fueling agreements:
Prepaid expenses and other current assets	$	2,593	$	—	$	2,593
Notes receivable and other long-term assets, net		2,035		—		2,035
Total derivative assets	$	4,628	$	—	$	4,628
Liabilities:
Commodity swaps:
Current portion of derivative liabilities, related party	$	1,875	$	—	$	1,875
Total derivative liabilities	$	1,875	$	—	$	1,875

As of December 31, 2022 and 2023, the Company had a total volume on open commodity swap contracts of 6.9 million and 1.9 million diesel gallons, respectively, at a weighted-average price of approximately $3.18 per gallon.

The following table reflects the weighted-average price of open commodity swap contracts as of December 31, 2022 and 2023, by year with associated volumes:


	December 31, 2022			December 31, 2023
	Volumes	Weighted-Average Price per		Volumes	Weighted-Average Price per
Year	(Diesel Gallons)	Diesel Gallon		(Diesel Gallons)	Diesel Gallon
2023	5,000,000	$	3.18	—	$	—
2024	1,875,000	$	3.18	1,875,000	$	3.18

Stockholders' Equity - Authorized Shares (Details)	Dec. 31, 2023 class Vote $ / shares shares	Dec. 31, 2022 $ / shares shares	Jun. 14, 2021 shares	Jun. 13, 2021 shares
Stockholders' Equity Note [Abstract]
Authorized number of classes of capital stock \| class	2
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001
Authorized shares (in shares)	455,000,000
Common stock, authorized (in shares)	454,000,000	454,000,000	454,000,000	304,000,000
Preferred stock, authorized (in shares)	1,000,000	1,000,000
Number of votes per share held by holders of common stock \| Vote	1

Land, Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Summary of land, property and equipment

Land, property and equipment, net as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Land	$	3,476	$	7,397
LNG liquefaction plants		94,790		96,786
Station equipment		353,104		418,647
Trailers		73,253		70,542
Other equipment		106,184		105,137
Construction in progress		91,105		125,389
		721,912		823,898
Less accumulated depreciation		(457,844)		(492,140)
Total land, property and equipment, net	$	264,068	$	331,758

Condensed Consolidated Statements of Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustment, tax	$ 0	$ 0	$ 0
Unrealized gains on available-for sale securities, tax	$ 0	$ 0	$ 0

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net loss	$ (100,098)	$ (59,590)	$ (94,155)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in 2022 and 2023	1,261	(1,773)	(1,394)
Unrealized gain (loss) on available-for-sale securities, net of $0 tax in 2022 and 2023	342	(327)	(19)
Total other comprehensive income (loss)	1,603	(2,100)	(1,413)
Comprehensive loss	(98,495)	(61,690)	(95,568)
Clean Energy Fuels Corp.
Net loss	(99,497)	(58,733)	(93,146)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in 2022 and 2023	1,261	(1,773)	(1,394)
Unrealized gain (loss) on available-for-sale securities, net of $0 tax in 2022 and 2023	342	(327)	(19)
Total other comprehensive income (loss)	1,603	(2,100)	(1,413)
Comprehensive loss	(97,894)	(60,833)	(94,559)
Noncontrolling Interest
Net loss	(601)	(857)	(1,009)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments, net of $0 tax in 2022 and 2023	0	0	0
Unrealized gain (loss) on available-for-sale securities, net of $0 tax in 2022 and 2023	0	0	0
Total other comprehensive income (loss)	0	0	0
Comprehensive loss	$ (601)	$ (857)	$ (1,009)

- Definition

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References + Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

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- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

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+ Details

Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Commodity Swap and Customer Contract
Gain (loss) due to changes in fair value	$ (0.2)	$ 0.5	$ (3.5)

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 1,475	$ 1,375
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	1,000,000	1,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	454,000,000	454,000,000
Common stock, issued (in shares)	223,026,966	222,437,429
Common stock, outstanding (in shares)	223,026,966	222,437,429

Investments in Other Entities and Noncontrolling Interest in a Subsidiary

12 Months Ended

Dec. 31, 2023

Investments, All Other Investments [Abstract]

Investments in Other Entities and Noncontrolling Interest in a Subsidiary

Note 4 —Investments in Other Entities and Noncontrolling Interest in a Subsidiary

TotalEnergies Joint Venture

On March 3, 2021, the Company entered into an agreement (the “TotalEnergies JV Agreement”) with TotalEnergies S.E. (“TotalEnergies”) to create 50/50 joint ventures to develop ADG RNG production facilities in the U.S. Pursuant to the TotalEnergies JV Agreement, each ADG RNG production facility project will be formed as a separate limited liability company (“LLC”) that is owned 50/50 by the Company and TotalEnergies, and contributions to such LLCs count toward the TotalEnergies JV Equity Obligations (as defined below). The TotalEnergies JV Agreement contemplates investing up to $400.0 million of equity in production projects, and TotalEnergies and the Company each committed to initially provide $50.0 million (the “TotalEnergies JV Equity Obligations”). In October 2021, TotalEnergies and the Company executed an LLC agreement (the “DR Development Agreement”) for an ADG RNG production facility project (the “DR JV”). Under the DR Development Agreement, TotalEnergies and the Company have each committed to contribute $7.0 million to the DR JV, and in November 2021, TotalEnergies and the Company each contributed an initial $4.8 million to the DR JV. On

June 27, 2023, the DR JV issued a capital call for $11.0 million in additional funding, requiring TotalEnergies and the Company each to contribute $5.5 million. Funds from the capital call will be used to fund required loan reserves and to paydown outstanding liabilities of the DR JV. On June 28, 2023, the Company contributed $5.5 million and advanced $5.5 million to the DR JV. In December 2023, the $5.5 million advance was refunded to the Company by the DR JV.

The Company accounts for its interest in the LLC using the equity method of accounting because the Company does not control but has the ability to exercise significant influence over the LLC’s operations. The Company recorded a loss of $0.1 million, $0.2 million, and $2.5 million from the LLC’s operations for the years ended December 31, 2021, 2022 and 2023, respectively. The Company had an investment balance of $4.5 million and $7.5 million as of December 31, 2022 and 2023, respectively.

The following table presents the combined summarized financial information of the TotalEnergies joint venture (in thousands):


	Year Ended December 31,
	2021		2022		2023
Revenue	$	—	$	—	$	1,462
Gross profit		—		—		173
Operating loss		(119)		(454)		(3,414)
Net loss	$	(119)	$	(454)	$	(4,951)


	As of December 31,
	2022		2023
Current assets	$	11	$	13,838
Non-current assets		32,773		33,289
Total assets	$	32,784	$	47,127

Current liabilities	$	4,326	$	2,518
Non-current liabilities		19,493		29,595
Total liabilities	$	23,819	$	32,113

bp Joint Venture

On April 13, 2021, the Company entered into an agreement (the “bp JV Agreement”) with bp that created a 50/50 joint venture (the “bpJV”) to develop, own and operate new ADG RNG production facilities in the U.S. Pursuant to the bp JV Agreement, bp and the Company committed to provide $50.0 million and $30.0 million, respectively, with bp and the Company each receiving 30.0 million of Class A Units in the bpJV and bp also receiving 20.0 million of Class B Units in the bpJV. bp’s initial $50.0 million contribution was made on April 13, 2021 and consisted of all unpaid principal outstanding under the loan agreement dated December 18, 2020, pursuant to which bp advanced $50.0 million to the Company to fund capital costs and expenses incurred prior to formation of the bpJV, including capital costs and expenses for permitting, engineering, equipment, leases and feed stock rights. Pursuant to the bp JV Agreement, the Company had the option, exercisable prior to August 31, 2021 (the “bp Option”), to commit an additional $20.0 million to the bpJV upon which bp’s Class B Units would convert into Class A Units. On June 21, 2021, the Company contributed $50.2 million to the bpJV, which consisted of (i) its initial contribution commitment of $30.0 million, (ii) the $20.0 million additional contribution to effect the conversion of bp’s Class B Units into Class A Units pursuant to the Company’s exercise of the bp Option, and (iii) $0.2 million for interest in accordance with the bp JV Agreement to effect the conversion of bp’s Class B Units into Class A Units.

On December 20, 2023, the bpJV issued a capital call in the amount of $135.9 million. As a result, bp and the Company each contributed $67.95 million to the bpJV by December 31, 2023. Proceeds of this capital call will be used to develop ADG RNG projects and to fund bpJV’s working capital needs.

As of December 31, 2023, the Company and bp each own 50% of the bpJV, and all of the RNG produced from projects developed and owned by the bpJV will be available to the Company for sale as vehicle fuel pursuant to the Company’s marketing agreement with bp. The Company accounts for its interest in the bpJV using the equity method of accounting because the Company does not control but has the ability to exercise significant influence over the bpJV’s operations. The Company recorded a loss of $0.4 million, $2.7 million, and $4.4 million from this investment for the years ended December 31, 2021, 2022 and 2023, respectively. The Company had an investment balance in the bpJV of $156.8 million and $220.3 million as of December 31, 2022 and 2023, respectively. Combined summarized financial information of the bpJV is as follows (in thousands):


	Year Ended December 31,
	2021		2022		2023
Revenue	$	—	$	—	$	—
Gross profit		—		—		—
Operating loss		(678)		(7,210)		(15,074)
Net loss		(603)		(5,485)		(10,241)
Net loss attributable to bpJV	$	(599)	$	(5,426)	$	(9,127)

			As of December 31,
			2022		2023
Current assets			$	157,241	$	209,973
Non-current assets				207,464		296,240
Total assets			$	364,705	$	506,213

Current liabilities			$	22,698	$	27,706
Non-current liabilities				2,716		13,558
Total liabilities			$	25,414	$	41,264

Equity attributable to shareowners of bpJV			$	313,544	$	440,613
Equity attributable to noncontrolling interest				25,747		24,336
Total equity			$	339,291	$	464,949

SAFE&CEC S.r.l.

SAFE&CEC S.r.l. is focused on manufacturing, selling and servicing natural gas fueling compressors and related equipment for the global natural gas fueling market. As of December 31, 2023, the Company owns a 49% ownership interest in SAFE&CEC S.r.l. The Company accounts for its interest in SAFE&CEC S.r.l. using the equity method of accounting because the Company does not control but has the ability to exercise significant influence over SAFE&CEC S.r.l.’s operations. The Company recorded income (loss) from this investment of $0.6 million, $(0.6) million and $(1.7) million for the years ended December 31, 2021, 2022 and 2023, respectively. The Company had an investment balance in SAFE&CEC S.r.l. of $21.8 million and $21.2 million as of December 31, 2022 and 2023, respectively. Summarized financial information of SAFE&CEC S.r.l. is as follows (in thousands):


	Year Ended December 31,
	2021		2022		2023
Revenue	$	109,119	$	110,104	$	97,740
Gross profit		25,784		24,902		24,098
Operating income		4,728		2,513		(562)
Net income (loss)	$	2,392	$	951	$	(2,148)


	As of December 31,
	2022		2023
Current assets	$	82,514	$	79,981
Non-current assets		60,187		59,636
Total assets	$	142,701	$	139,617

Current liabilities	$	73,931	$	70,193
Non-current liabilities		20,248		20,888
Total liabilities	$	94,179	$	91,081

Other Equity Method Investments

The Company had investment balances in other equity method investments totaling $2.2 million and $1.8 million as of December 31, 2022 and 2023, respectively. The Company recorded income (loss) from other equity method investments of $(0.6) million, $(1.2) million, and $(3.9) million for the years ended December 31, 2021, 2022 and 2023, respectively. The Company accounts for its interest using the equity method of accounting because the Company does not control but has the ability to exercise significant influence over the investees’ operations. Combined summarized financial information of the Company’s other equity method investments is as follows (in thousands):


	Year Ended December 31,
	2021		2022		2023
Revenue	$	704	$	1,217	$	615
Gross profit		216		506		327
Operating loss		(1,757)		(2,556)		(4,513)
Net loss	$	(1,793)	$	(2,585)	$	(4,539)


	As of December 31,
	2022		2023
Current assets	$	1,652	$	1,436
Non-current assets		4,609		4,281
Total assets	$	6,261	$	5,717

Current liabilities	$	1,169	$	1,231
Non-current liabilities		2,383		6,312
Total liabilities	$	3,552	$	7,543

NG Advantage

On October 14, 2014, the Company entered into a Common Unit Purchase Agreement (“UPA”) with NG Advantage for a 53.3% controlling interest in NG Advantage. NG Advantage is engaged in the business of transporting CNG in high-capacity trailers to industrial and institutional energy users, such as hospitals, food processors, manufacturers and paper mills that do not have direct access to natural gas pipelines.

In connection with the arrangement between NG Advantage and bp for the supply, sale and reservation of a specified volume of CNG transportation capacity until February 2022, on February 28, 2018, the Company entered into a guaranty agreement with NG Advantage and bp pursuant to which the Company guaranteed NG Advantage’s payment obligations to bp in the event of default by NG Advantage under the supply arrangement, in an amount up to an aggregate of $30.0 million plus related fees which was subsequently reduced to $15.0 million effective June 24, 2020. As initial consideration

for the guaranty agreement, NG Advantage issued to the Company 19,660 common units, which increased the Company’s controlling interest in NG Advantage from 53.3% to 53.5%.

On October 1, 2018, the Company purchased 1,000,001 common units from NG Advantage for an aggregate cash purchase price of $5.0 million. This purchase increased Clean Energy’s controlling interest in NG Advantage from 53.5% to 61.7%.

In each month from November 2018 through February 2019, the Company was issued 100,000 additional common units of NG Advantage, for a total of 400,000 common units, pursuant to the guaranty agreement entered in February 2018. The issuance of 400,000 additional common units increased the Company’s controlling interest in NG Advantage to 64.6%.

During the year ended December 31, 2019, the Company agreed to lend NG Advantage up to $26.7 million under a series of promissory notes that were incorporated into a delayed draw convertible promissory note (the “November 2019 Convertible Note”). In connection with the promissory notes between NG Advantage and the Company, NG Advantage issued to the Company warrants to purchase 2,086,879 common units. On February 6, 2020, the Company converted the outstanding principal and accrued interest under the November 2019 Convertible Note into common units of NG Advantage, resulting in an increase in the Company’s controlling interest in NG Advantage from 64.6% to 93.2%.

On February 29, 2020, NG Advantage issued to the Company 283,019 common units of NG Advantage pursuant to the guaranty agreement entered into in February 2018, increasing the Company’s controlling interest in NG Advantage to 93.3%. On February 28, 2022, the supply arrangement between NG Advantage and bp expired. As a result, the Company’s obligations under the guaranty agreement entered into in February 2018 were fully released. As of December 31, 2023, the Company’s controlling interest in NG Advantage remained at 93.3%.

For the year ended December 31, 2022, NG Advantage borrowed $29.1 million from the Company under a series of advance agreements. There were no borrowings by NG Advantage in the year ended December 31, 2023. As of December 31, 2022 and 2023, NG advantage had a total outstanding principal balance of $47.5 million, plus accrued and unpaid interest under the advance agreements. These intercompany transactions have been eliminated in consolidation.

The Company recorded a loss attributable to the noncontrolling interest in NG Advantage of $1.0 million, $0.9 million, and $0.6 million for the years ended December 31, 2021, 2022 and 2023, respectively. The noncontrolling interest was $7.5 million and $6.9 million as of December 31, 2022 and 2023, respectively.

Investments in Equity Securities

For investments in equity securities of privately held entities without readily determinable fair values, the Company measures such investments at cost, adjusted for impairment, if any, and observable price changes in orderly transactions for the identical or similar investment of the same issuer. As of December 31, 2022 and 2023, the Company had an investment balance recorded at cost of $8.0 million. The Company did not recognize any adjustments to the recorded cost basis during the years ended December 31, 2022 and 2023.

Debt

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Debt

Note 12 —Debt

Debt obligations as of December 31, 2022 and 2023 consisted of the following (in thousands):


	December 31, 2022
			Unamortized Debt		Balance, Net of
	Principal Balance		Financing Costs		Financing Costs
Riverstone Term Loan	$	150,000	$	4,529	$	145,471
Other debt		93		—		93
Total debt		150,093		4,529		145,564
Less amounts due within one year		(93)		—		(93)
Total long-term debt	$	150,000	$	4,529	$	145,471


	December 31, 2023
			Unamortized Debt		Balance, Net of
	Principal Balance		Financing Costs		Financing Costs
Stonepeak Term Loan	$	300,000	$	39,094	$	260,906
Other debt		255		—		255
Total debt		300,255		39,094		261,161
Less amounts due within one year		(38)		—		(38)
Total long-term debt	$	300,217	$	39,094	$	261,123

The following is a summary of the aggregate maturities of debt obligations for each of the annual periods subsequent to December 31, 2023 (in thousands):


	2024		2025		2026		2027		2028		Thereafter		Total
Stonepeak Term Loan	$	—	$	—	$	—	$	—	$	—	$	300,000	$	300,000
Other Debt		38		44		50		57		66		—		255
Total	$	38	$	44	$	50	$	57	$	66	$	300,000	$	300,255

Stonepeak Credit Agreement

On December 12, 2023 (the “Stonepeak Closing Date”), the Company entered into a senior secured first lien term loan credit agreement (the “Stonepeak Credit Agreement”) with a syndicate of lenders. Pursuant to the Stonepeak Credit Agreement, the lenders funded a $300,000,000 senior secured term loan (the “Senior Term Loan”) and provided a delayed draw term loan commitment of $100,000,000 (together, with the Senior Term Loan, the “Loan Facility”). Payments related to the Loan Facility are interest only with a balloon principal payment due on the maturity date, which is December 12, 2029. The Loan Facility bears interest at 9.50% per annum, and, during the first two years beginning from the Stonepeak Closing Date, the Company may elect to pay up to 75% of the interest in kind. The delayed draw term loan commitment has a scheduled expiration date of December 12, 2025, and outstanding undrawn principal of the commitment is subject to a commitment fee of 1.00% per annum. The Company has the option to early terminate the delayed draw term loan commitment subject to the payment of certain early termination fees. Proceeds from the Loan Facility were or will be used to repay certain existing indebtedness of the Company, to finance permitted investments from time to time, to pay transaction costs related to the Stonepeak Credit Agreement, and for other general corporate purposes. In connection with the Loan Facility, the Company is obligated to pay other customary facility fees for credit facilities of a similar size and type.

The Company has the option to prepay all or any portion of the amounts owed prior to the maturity date, and the Loan Facility is subject to customary mandatory prepayments clauses. All prepayments and all other payments of the Loan Facility principal are subject to a call premium in the minimum amount that, when received by the lenders, would be sufficient to cause both (1) the internal rate of return for each such lender on the Loan Facility to be not less than 11.5% and (2) the multiple on invested capital for each such lender to be not less than 1.40; provided, however, in the event that the Company consummates a change in control transaction, in lieu of the foregoing call premium, the Company is obligated to pay a change in control premium in the amount of (a) the principal amount of the loans outstanding at the time of such change in control multiplied by, if the change in control occurs on or prior to the first anniversary of the Stonepeak Closing Date, 20%, (b) the principal amount of the loans outstanding at the time of such change in control multiplied by, if the change in control occurs after the first anniversary of the Stonepeak Closing Date but on or prior to the second anniversary of the Stonepeak Closing Date, 10%, and (c) if the change in control occurs after the second anniversary of the Stonepeak Closing Date, the minimum amount that, when received by the lenders, would be sufficient to cause the internal rate of return for each such lender to be not less than 11.5%. In conjunction with the Stonepeak Credit Agreement, the Company entered into a Guarantee and Collateral Agreement (the “Security Agreement”) in favor of the lenders. Pursuant to the Security Agreement, the Company granted the lenders a security interest in substantially all of its personal property, rights and assets to secure the payment of all amounts owed to the lenders under the Stonepeak Credit Agreement. Certain material subsidiaries of the Company will be required to join as a party to the Security Agreement from time to time after the Stonepeak Closing Date.

The Stonepeak Credit Agreement requires the Company to comply with a maximum total leverage ratio, a minimum interest coverage ratio and a minimum liquidity test. In addition, the Stonepeak Credit Agreement contains customary representations and warranties and affirmative and negative covenants, including covenants that limit or restrict the Company’s ability to incur liens, incur indebtedness, dispose of assets, make investments, make certain restricted payments, merge or consolidate and enter into certain speculative hedging arrangements. Additionally, the Stonepeak Credit Agreement includes a number of events of default contingency clauses, including, among other things, non-payment defaults, covenant defaults, cross-defaults to other materials indebtedness, bankruptcy and insolvency defaults, material

judgment defaults, and material breaches of material contracts. If any event of default occurs (subject, in certain instances, to specified grace periods), the principal, premium, if any, interest and any other monetary obligations on all the then outstanding amounts under the Loan Facility may become due and payable immediately.

Concurrent with the execution of the Stonepeak Credit Agreement, the Company issued warrants to Stonepeak CLNE-W Holdings LP (“Stonepeak”), pursuant to a Warrant Agreement, dated December 12, 2023, allowing Stonepeak to purchase 10,000,000 shares of the Company’s common stock at an exercise price of $5.50 and an additional 10,000,000 shares of the Company’s common stock at an exercise price of $6.50 (see Note 13). Further, in connection with the funding of the Senior Term Loan pursuant to the Stonepeak Credit Agreement, the Company recognized $39.3 million in debt discount and issuance costs, which consisted of $31.8 million of debt discount attributed to the Stonepeak Warrant, $6.1 million of original issue discount and direct lender fees, and $1.4 million of debt issuance costs.

Riverstone Credit Agreement

On December 22, 2022 (the “Riverstone Closing Date”), the Company entered into a senior secured first lien term loan credit agreement (the “Riverstone Credit Agreement”) with a syndicate of lenders. Pursuant to the Riverstone Credit Agreement, the lenders made a $150,000,000 sustainability-linked senior secured term loan (the “Sustainability-Linked Term Loan”) to the Company, a transaction aligned with the five pillars of the Loan Syndications and Trading Association’s sustainability-linked loan principles. Payments for the Sustainability-Linked Term Loan are interest only with a balloon principal payment due on the maturity date, which is December 22, 2026. The Sustainability-Linked Term Loan bears interest, at the option of the Company, at (a) Adjusted Term SOFR or (b) the Alternate Base Rate (“ABR”), which is defined as the greater of (i) the Prime Rate, (ii) the Federal Funds Effective Rate plus 0.50%, and (iii) one-month Adjusted Term SOFR plus 1.00%, plus an applicable margin of 6.50% for interest rate based on SOFR or 5.50% for election under the ABR through the second anniversary of the Riverstone Closing Date. After the second anniversary of the Riverstone Closing Date, the applicable margin increases to 7.25% for election under SOFR or 6.25% for election under the ABR. The applicable margin is subject to a sustainability rate adjustment feature, which may increase the applicable margin by 25 basis points if certain KPI metric is not met for fiscal years beginning after December 31, 2024. The sustainability rate adjustment feature shall be applied retroactively to commence as of December 31, 2025. Interest rate for the Sustainability-Linked Term Loan has an interest rate floor of 1.50% for election under SOFR and 2.50% for election under the ABR. Proceeds from the Sustainability-Linked Term Loan were or will be used to repay certain existing indebtedness of the Company, to finance permitted investments from time to time, to pay transaction costs related to the Riverstone Credit Agreement and for other general corporate purposes. In connection with the Sustainability-Linked Term Loan, the Company is obligated to pay other facility fees customary for credit facilities of similar size and type.

The Company has the option to prepay all or any portion of the amounts owed prior to the maturity date and is subject to customary mandatory prepayments clauses. All prepayments and all other payments of the Sustainability-Linked Term Loan principal are subject to a call premium (2.0% from the one-year anniversary of the Riverstone Closing Date to the date that is eighteen months after the Riverstone Closing Date, 2.5% after the date that is eighteen months after the Riverstone Closing Date to the date that is twenty-four months after the Riverstone Closing Date, and 3% at any time thereafter). No call premium applies to any prepayment of the Sustainability-Linked Term Loan made prior to the first anniversary of the Riverstone Closing Date. In conjunction with the Riverstone Credit Agreement, the Company and certain of its subsidiaries entered into a Guarantee and Collateral Agreement (the “Security Agreement”) in favor of the lenders. Under the Security Agreement, the Company and certain of its subsidiaries granted the lenders a security interest in substantially all of their personal property, rights and assets as collateral for the Sustainability-Linked Term Loan under the Riverstone Credit Agreement. The Company and certain of its subsidiaries also agreed to grant a security interest in certain of their material real property interests.

The Riverstone Credit Agreement contains customary representations, warranties, and affirmative and negative covenants, including compliance with certain financial ratios and liquidity test and limitation on the Company’s ability to incur additional indebtedness, make certain payments, and enter into certain transactions. Additionally, the Riverstone Credit Agreement includes a number of events of default clauses. If any event of default occurs (subject, in certain

instances, to specified grace periods), the then outstanding principal, premium, if any, interest and any other monetary obligations under the Riverstone Credit Agreement may become due and payable immediately.

On December 12, 2023, concurrent with the execution of the Stonepeak Credit Agreement, the Company repaid the $150.0 million outstanding principal balance of the Sustainability-Linked Term Loan and related accrued and unpaid interest. Upon such payment, the Riverstone Credit Agreement, dated as of December 22, 2022, was terminated. In connection with the extinguishment of the Sustainability-Linked Term Loan pursuant to the Riverstone Credit Agreement, the Company recognized $5.4 million of debt extinguishment loss, which was included in “Interest expense” in the accompanying consolidated statements of operations for the year ended December 31, 2023.

Other Debt

In May 2023, the Company entered into a sale and leaseback arrangement and received $0.3 million pursuant to the arrangement. The transaction did not qualify for sale and leaseback accounting due to a fixed price repurchase option that is not at fair value. As a result, the transaction was recorded under the financing method in which the assets remained on the accompanying consolidated balance sheets, and the proceeds from the transaction were recorded as a financing liability. The sale and leaseback arrangement has a term of five years with interest and principal payable in 60 monthly installments at an annual effective rate of 13.38%. As of December 31, 2022 and December 31, 2023, the Company had other outstanding debt bearing interest at 4.75% and 13.38%, respectively.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 470
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//470/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

Investments in Other Entities and Noncontrolling Interest in a Subsidiary - SAFE&CEC S.r.l (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ (12,510)	$ (4,824)	$ (430)
SAFE&CEC S.r.l.
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)	49.00%
Income (loss) from equity method investments	$ (1,700)	(600)	$ 600
Investment balance	$ 21,200	$ 21,800

Leases - Maturities of Finance and Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Finance Leases
2023	$ 1,979
2024	1,073
2025	593
2026	362
2027	3
Total minimum lease payments	4,010
Less amount representing interest	(413)
Present value of lease liabilities	3,597	$ 3,082
Operating Leases
2023	15,125
2024	15,406
2025	15,363
2026	15,359
2027	14,531
Thereafter	75,759
Total minimum lease payments	151,543
Less amount representing interest	(55,791)
Present value of lease liabilities	$ 95,752	$ 53,117

Stockholders' Equity - Stonepeak Warrant Activity (Details) - Stonepeak Warrant	12 Months Ended
	Dec. 31, 2023 USD ($) shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding and unvested Beginning Balance \| $	$ 0
Granted \| shares	20,000,000
Exercised \| shares	0
Outstanding and unvested as of Ending Balance \| $	$ 20,000,000

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2023	Feb. 22, 2024	Jun. 30, 2023
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Securities Act File Number	001-33480
Entity Registrant Name	CLEAN ENERGY FUELS CORP.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0968580
Entity Address, Address Line One	4675 MacArthur Court
Entity Address, Address Line Two	Suite 800
Entity Address, City or Town	Newport Beach
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92660
City Area Code	949
Local Phone Number	437-1000
Title of 12(b) Security	Common stock, $0.0001 par value per share
Trading Symbol	CLNE
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		223,238,496
Entity Public Float			$ 879,338,902
Auditor Name	KPMG LLP
Auditor Firm ID	185
Auditor Location	Irvine, California
Entity Central Index Key	0001368265
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Amendment Flag	false

Stockholders' Equity - Restricted Stock Units (Details) - Service-Based RSUs - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Number of Shares
Outstanding at the beginning of the period (in shares)	694,945
Granted (in shares)	129,524
Vested (in shares)	(418,274)
Forfeited or expired (in shares)	(6,486)
Outstanding at the end of the period (in shares)	399,709	694,945
Weighted Average Fair Value at Grant Date
Outstanding at the beginning of the period (in dollars per share)	$ 8.41
Granted (in dollars per share)	4.19	$ 6.41	$ 10.24
Vested (in dollars per share)	7.38
Forfeited or expired (in dollars per share)	10.08
Outstanding at the end of the period (in dollars per share)	$ 8.10	$ 8.41
Unrecognized compensation cost	$ 0.6
Unrecognized compensation cost, weighted-average period	7 months 6 days
Stock-based compensation expense	$ 3.0	$ 3.1	$ 3.9
Vesting over the first year
Stock-based compensation
Vesting percentage	34.00%
Vesting over the second year
Stock-based compensation
Vesting percentage	33.00%
Vesting over the third year
Stock-based compensation
Vesting percentage	33.00%

Revenue from Contracts with Customers - Contract Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Contract with customer, liability, revenue recognized	$ 4.9
Revenue recognized during period		$ 2.6

Investments in Other Entities and Noncontrolling Interest in a Subsidiary - NG Advantage (Details) - USD ($)					1 Months Ended				4 Months Ended	12 Months Ended
	Feb. 29, 2020	Feb. 06, 2020	Oct. 01, 2018	Feb. 28, 2018	Feb. 28, 2019	Jan. 31, 2019	Dec. 31, 2018	Nov. 30, 2018	Feb. 28, 2019	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 24, 2020	Oct. 14, 2014
Schedule of Equity Method Investments [Line Items]
Outstanding balance										$ 261,161,000	$ 145,564,000
Payments to acquire additional controlling interest										73,450,000	89,700,000	$ 78,919,000
Loss from noncontrolling interest										(601,000)	(857,000)	(1,009,000)
Investments carried at cost										8,000,000.0
NG Advantage
Schedule of Equity Method Investments [Line Items]
Purchase of interest by parent, shares purchased (in shares)			1,000,001
Debt issuance amount										0	$ 29,100,000
Outstanding balance										47,500,000
Ownership interest before transaction (as a percent)		64.60%	53.50%	53.30%
Ownership interest after transaction (as a percent)		93.20%	61.70%	53.50%					64.60%		93.30%
Payments to acquire additional controlling interest			$ 5,000,000.0
Loss from noncontrolling interest										(600,000)	$ (900,000)	$ 1,000,000.0
Noncontrolling interest, fair value										$ 6,900,000	$ 7,500,000
NG Advantage \| Payment Obligations
Schedule of Equity Method Investments [Line Items]
Purchase of interest by parent, shares purchased (in shares)				19,660	100,000	100,000	100,000	100,000	400,000
November 2019 Convertible Note \| NG Advantage
Schedule of Equity Method Investments [Line Items]
Number of common units to be called by warrants (in shares)												2,086,879
Debt issuance amount												$ 26,700,000
Common unit purchase agreement \| NG Advantage
Schedule of Equity Method Investments [Line Items]
Issuance of equity by subsidiary to parent (in shares)	283,019
Ownership interest acquired														53.30%
Ownership interest after transaction (as a percent)										93.30%
Long-Term Natural Gas Purchase Contracts \| BP Products North America \| NG Advantage
Schedule of Equity Method Investments [Line Items]
Contingent consideration, liability (up to)				$ 30,000,000.0									$ 15,000,000.0

Debt (Tables)

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Schedule of long-term debt

Debt obligations as of December 31, 2022 and 2023 consisted of the following (in thousands):


	December 31, 2022
			Unamortized Debt		Balance, Net of
	Principal Balance		Financing Costs		Financing Costs
Riverstone Term Loan	$	150,000	$	4,529	$	145,471
Other debt		93		—		93
Total debt		150,093		4,529		145,564
Less amounts due within one year		(93)		—		(93)
Total long-term debt	$	150,000	$	4,529	$	145,471


	December 31, 2023
			Unamortized Debt		Balance, Net of
	Principal Balance		Financing Costs		Financing Costs
Stonepeak Term Loan	$	300,000	$	39,094	$	260,906
Other debt		255		—		255
Total debt		300,255		39,094		261,161
Less amounts due within one year		(38)		—		(38)
Total long-term debt	$	300,217	$	39,094	$	261,123

Summary of aggregate maturities of long term debt and capital lease obligations

The following is a summary of the aggregate maturities of debt obligations for each of the annual periods subsequent to December 31, 2023 (in thousands):


	2024		2025		2026		2027		2028		Thereafter		Total
Stonepeak Term Loan	$	—	$	—	$	—	$	—	$	—	$	300,000	$	300,000
Other Debt		38		44		50		57		66		—		255
Total	$	38	$	44	$	50	$	57	$	66	$	300,000	$	300,255

Fair Value Measurements - Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets:
Available-for-sale securities	$ 158,186	$ 139,569
Short-term investments	158,186	139,569
U.S. government securities
Assets:
Available-for-sale securities	157,656	64,880
Zero coupon bonds
Assets:
Available-for-sale securities		74,159
Convertible promissory note
Assets:
Available-for-sale securities		1,880
Certificates of deposit
Assets:
Available-for-sale securities	530	530
Level 3 \| Convertible promissory note
Assets:
Available-for-sale securities		1,880
Fair value measured on recurring basis \| U.S. government securities
Assets:
Available-for-sale securities	157,656
Fair value measured on recurring basis \| Zero coupon bonds
Assets:
Available-for-sale securities		74,159
Fair value measured on recurring basis \| Convertible promissory note
Assets:
Available-for-sale securities	2,330
Fair value measured on recurring basis \| Certificates of deposit
Assets:
Short-term investments	530	530
Fair value measured on recurring basis \| Embedded derivatives
Assets:
Derivative assets	4,628	6,755
Fair value measured on recurring basis \| Commodity swap contracts
Liabilities:
Derivative liabilities	1,875	3,845
Fair value measured on recurring basis \| Municipal bonds and notes
Assets:
Available-for-sale securities		64,880
Fair value measured on recurring basis \| Level 1 \| U.S. government securities
Assets:
Available-for-sale securities	157,656
Fair value measured on recurring basis \| Level 1 \| Municipal bonds and notes
Assets:
Available-for-sale securities		64,880
Fair value measured on recurring basis \| Level 2 \| Zero coupon bonds
Assets:
Available-for-sale securities		74,159
Fair value measured on recurring basis \| Level 2 \| Certificates of deposit
Assets:
Short-term investments	530	530
Fair value measured on recurring basis \| Level 3 \| Convertible promissory note
Assets:
Available-for-sale securities	2,330
Fair value measured on recurring basis \| Level 3 \| Embedded derivatives
Assets:
Derivative assets	4,628	6,755
Fair value measured on recurring basis \| Level 3 \| Commodity swap contracts
Liabilities:
Derivative liabilities	$ 1,875	$ 3,845

Debt - Stonepeak Credit Agreement (Details)	Dec. 12, 2023 USD ($) item $ / shares shares
Stonepeak Warrants
Debt Instrument [Line Items]
Unamortized debt discount	$ 31,800,000
Stonepeak Warrants, With Exercise Price Of Dollars 5.50
Debt Instrument [Line Items]
Aggregate number of warrant shares (in shares) \| shares	10,000,000
Exercise price of the warrant (in dollars per share) \| $ / shares	$ 5.50
Stonepeak Warrants, With Exercise Price Of Dollars 6.50
Debt Instrument [Line Items]
Aggregate number of warrant shares (in shares) \| shares	10,000,000
Exercise price of the warrant (in dollars per share) \| $ / shares	$ 6.50
Stonepeak Loan Facility
Debt Instrument [Line Items]
Interest rate	9.50%
Percentage of interest company may elect to pay in kind	75.00%
Period of company may elect to payment of interest in kind	2 years
Internal rate of return for each lender under loan facility	11.50%
Minimum multiple on invested capital for each lender under credit facility \| item	1.40
Debt issuance costs net	$ 39,300,000
Original issue discount and direct lender fees	6,100,000
Debt issuance costs	$ 1,400,000
Stonepeak Loan Facility \| If Change In Control Occurs On Or Prior To First Anniversary Of Loan Facility Closing Date [Member]
Debt Instrument [Line Items]
Change in control premium percentage	20.00%
Stonepeak Loan Facility \| If Change In Control Occurs After First Anniversary Of Loan Facility Closing Date But On Or Prior To Second Anniversary Of Loan Facility Closing Date [Member]
Debt Instrument [Line Items]
Change in control premium percentage	10.00%
Stonepeak Loan Facility \| If Change In Control Occurs After Second Anniversary Of Loan Facility Closing Date [Member]
Debt Instrument [Line Items]
Internal rate of return for each lender under loan facility	11.50%
Stonepeak Term Loan
Debt Instrument [Line Items]
Debt issuance amount	$ 300,000,000
Stonepeak delayed draw term loan
Debt Instrument [Line Items]
Debt issuance amount	$ 100,000,000
Commitment fee	1.00%

Concentrations

12 Months Ended

Dec. 31, 2023

Concentrations [Abstract]

Concentrations

Note 21 —Concentrations

During the years ended December 31, 2021, 2022 and 2023, zero, one, and one supplier, respectively, each accounted for 10% or more of the Company’s natural gas expense relating to CNG and LNG purchases.

During the years ended December 31, 2021, 2022 and 2023, no single customer accounted for 10% or more of the Company’s total revenue.

Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net loss attributable to Clean Energy Fuels Corp.	$ (99,497)	$ (58,733)	$ (93,146)
Weighted-average common shares outstanding	222,904,785	222,414,790	213,118,694
Dilutive effect of potential common shares from restricted stock units and stock options	0	0	0
Weighted-average common shares outstanding - diluted	222,904,785	222,414,790	213,118,694
Basic loss per share (in dollars per share)	$ (0.45)	$ (0.26)	$ (0.44)
Diluted loss per share (in dollars per share)	$ (0.45)	$ (0.26)	$ (0.44)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482635/260-10-55-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (e)(4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480175/815-40-65-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-11

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-7

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Stockholders' Equity - Stonepeak Warrant (Details) - USD ($)		3 Months Ended	12 Months Ended
	Dec. 12, 2023	Dec. 31, 2023	Dec. 31, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of warrant			$ 42,435,000
Stonepeak Loan Facility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt issuance costs net	$ 39,300,000
Debt Instrument, Original Issue Discount And Direct Lender Fees	6,100,000
Debt issuance costs	1,400,000
Stonepeak Term Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt issuance amount	300,000,000
Stonepeak delayed draw term loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt issuance amount	$ 100,000,000
Stonepeak Warrant
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Instrument, Original Issue Discount And Direct Lender Fees		$ 31,800,000	31,800,000
Warrant outstanding term	8 years 6 months
Beneficial ownership percentage	9.999%
Number of days written notice required to waive beneficial ownership limitation	61 days
Fair value of warrant		42,400,000
Warrant asset		10,600,000	10,600,000
Debt issuance amount		$ 100,000,000.0	$ 100,000,000.0
Stonepeak Warrant \| Stonepeak Warrant Agreement at $5.50 Exercise Price \| Black-Scholes option pricing model \| Exercise price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	5.50
Stonepeak Warrant \| Stonepeak Warrant Agreement at $5.50 Exercise Price \| Black-Scholes option pricing model \| Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	0.0
Stonepeak Warrant \| Stonepeak Warrant Agreement at $5.50 Exercise Price \| Black-Scholes option pricing model \| Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	72.96
Stonepeak Warrant \| Stonepeak Warrant Agreement at $5.50 Exercise Price \| Black-Scholes option pricing model \| Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	4.22
Stonepeak Warrant \| Stonepeak Warrant Agreement at $5.50 Exercise Price \| Black-Scholes option pricing model \| Expected term in years
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	8.5
Stonepeak Warrant \| Stonepeak Warrant Agreement at $6.50 Exercise Price \| Black-Scholes option pricing model \| Exercise price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	6.50
Stonepeak Warrant \| Stonepeak Warrant Agreement at $6.50 Exercise Price \| Black-Scholes option pricing model \| Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	0.0
Stonepeak Warrant \| Stonepeak Warrant Agreement at $6.50 Exercise Price \| Black-Scholes option pricing model \| Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	72.96
Stonepeak Warrant \| Stonepeak Warrant Agreement at $6.50 Exercise Price \| Black-Scholes option pricing model \| Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	4.22
Stonepeak Warrant \| Stonepeak Warrant Agreement at $6.50 Exercise Price \| Black-Scholes option pricing model \| Expected term in years
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	8.5
Stonepeak Warrants, With Exercise Price Of Dollars 5.50
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Aggregate number of warrant shares (in shares)	10,000,000
Exercise price of the warrant (in dollars per share)	$ 5.50
Stonepeak Warrants, With Exercise Price Of Dollars 6.50
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Aggregate number of warrant shares (in shares)	10,000,000
Exercise price of the warrant (in dollars per share)	$ 6.50

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Schedule of information by level for assets and liabilities that are measured at fair value on a recurring basis


	December 31, 2022		Level 1		Level 2		Level 3
Assets:
Available-for-sale securities:
U.S. government securities⁽¹⁾	$	64,880	$	64,880	$	—	$	—
Zero coupon bonds⁽¹⁾		74,159		—		74,159		—
Convertible promissory note⁽⁴⁾		1,880		—		—		1,880
Certificates of deposit ⁽¹⁾		530		—		530		—
Embedded derivatives ⁽³⁾		6,755		—		—		6,755
Liabilities:
Commodity swap contracts ⁽²⁾	$	3,845	$	—	$	—	$	3,845


	December 31, 2023		Level 1		Level 2		Level 3
Assets:
Available-for-sale securities:
U.S. government securities⁽¹⁾	$	157,656	$	157,656	$	—	$	—
Convertible promissory note⁽⁴⁾		2,330		—		—		2,330
Certificates of deposit ⁽¹⁾		530		—		530		—
Embedded derivatives ⁽³⁾		4,628		—		—		4,628
Liabilities:
Commodity swap contracts ⁽²⁾	$	1,875	$	—	$	—	$	1,875

(1)	Included in “Short-term investments” in the accompanying consolidated balance sheets. See Note 6 for more information.

(2)	Included in “Derivative liabilities, related party” and “Long-term portion of derivative liabilities, related party” as of December 31, 2022 and in “Derivative liabilities, related party” as of December 31, 2023 in the accompanying consolidated balance sheets. See Note 7 for more information.

(3)	Included in “Prepaid expenses and other current assets” and “Notes receivable and other long-term assets, net” as of December 31, 2022 and 2023 in the accompanying consolidated balance sheets. See Note 7 for more information.

(4)	Included in “Notes receivable and other long-term assets, net” as of December 31, 2022 and in “Other receivables” as of December 31, 2023 in the accompanying consolidated balance sheets.

Schedule of reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis that used significant unobservable inputs (Level 3)

The following table provides a reconciliation of the beginning and ending balances of items measured at fair value on a recurring basis as shown in the tables above that used significant unobservable inputs (Level 3), as well as the change in unrealized gains or losses for the periods included in earnings or other comprehensive income (loss) (in thousands):


	Assets:		Assets:		Liabilities:
	Embedded		Convertible		Commodity
	Derivatives		Promissory Note		Swap Contracts
Balance as of December 31, 2021	$	6,776	$	—	$	(4,383)
Settlements, net		—		—		7,761
Total gain (loss)		(21)		(134)		(7,223)
Purchases		—		2,014		—
Balance as of December 31, 2022	$	6,755	$	1,880	$	(3,845)

Balance as of December 31, 2022	$	6,755	$	1,880	$	(3,845)
Settlements, net		—		—		4,858
Total gain (loss)		(2,127)		103		(2,888)
Purchases		—		3,822		—
Equity method investment loss		—		(3,475)		—
Balance as of December 31, 2023	$	4,628	$	2,330	$	(1,875)

Change in unrealized gain (loss) for the year ended December 31, 2022 included in earnings	$	(21)	$	—	$	538
Change in unrealized gain (loss) for the year ended December 31, 2023 included in earnings	$	(2,127)	$	—	$	1,970
Change in unrealized gain (loss) for the year ended December 31, 2022 included in other comprehensive income (loss)	$	—	$	(134)	$	—
Change in unrealized gain (loss) for the year ended December 31, 2023 included in other comprehensive income (loss)	$	—	$	103	$	—

Schedule of Debt Instruments at Fair Value

Debt instruments as of December 31, 2023 consisted of the following (in thousands):


	Net Carrying		Estimated
	Amounts		Fair Value
Stonepeak Term Loan	$	260,906	$	253,303
Other Debt		255		255
Total Debt	$	261,161	$	253,558

Commodity swaps

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Schedule of fair value inputs

The Company estimated the fair value of its outstanding commodity swap contracts based on the following inputs as of December 31, 2022 and 2023:


	December 31, 2022			December 31, 2023
Significant Unobservable Inputs	Input Range	Weighted Average		Input Range	Weighted Average
ULSD Gulf Coast Forward Curve	$2.35 - $2.59	$	2.48	$ 1.97 - $ 2.27	$	2.15
Historical Differential to PADD 3 Diesel	$0.88 - $1.62	$	1.13	$ 0.92 - $ 1.62	$	1.16
Historical Differential to PADD 5 Diesel	$1.89 - $3.00	$	2.30	$ 1.89 - $ 3.16	$	2.48

The Company estimated the fair value of embedded derivatives in its fueling agreements under the Zero Now truck financing program based on the following inputs as of December 31, 2022 and 2023:


	December 31, 2022			December 31, 2023
Significant Unobservable Inputs	Input Range	Weighted Average		Input Range	Weighted Average
ULSD Gulf Coast Forward Curve	$2.35 - $2.59	$	2.48	$ 1.97 - $ 2.27	$	2.15
Historical Differential to PADD 3 Diesel	$0.88 - $1.62	$	1.13	$ 0.92 - $ 1.62	$	1.16
Historical Differential to PADD 5 Diesel	$1.91 - $3.05	$	2.31	$ 1.89 - $ 3.16	$	2.48

Convertible promissory note

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Schedule of fair value inputs

The following table provides quantitative information about the significant inputs used to estimate the fair value of the convertible promissory note as of December 31, 2022 and 2023:



Significant Unobservable Inputs	December 31, 2022	December 31, 2023
Risk-free interest rate	4.57%	5.39%
Credit adjustment	8.36%	5.31%
Credit adjusted discount rate	12.93%	10.70%

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of components of income loss before income taxes

The components of loss before income taxes for the years ended December 31, 2021, 2022 and 2023 are as follows (in thousands):


	2021		2022		2023
U.S.	$	(93,117)	$	(58,431)	$	(99,749)
Foreign		(919)		(939)		(772)
Total loss before income taxes	$	(94,036)	$	(59,370)	$	(100,521)

Schedule of provision for income taxes

The provision for income taxes for the years ended December 31, 2021, 2022 and 2023 consists of the following (in thousands):


	2021		2022		2023
Current:
State	$	54	$	47	$	92
Foreign		(4)		—		—
Total current		50		47		92
Deferred:
Federal		18		78		(318)
State		51		95		(197)
Total deferred		69		173		(515)
Total expense	$	119	$	220	$	(423)

Schedule of reconciliation of federal income tax rate to the actual effective tax rate


	2021		2022		2023
Computed expected tax (benefit)	$	(19,747)	$	(12,468)	$	(21,110)
Nondeductible expenses		617		4,218		1,062
Tax rate differential on foreign earnings		189		197		162
Joint ventures		(2)		441		1,035
Amazon warrants		3,707		1,134		5,381
Tax credits		(5,299)		(6,065)		(6,250)
Other		1,463		843		(48)
Change in valuation allowance		19,191		11,920		19,345
Total tax expense	$	119	$	220	$	(423)

Schedule of tax effect of temporary differences that give rise to deferred tax assets and liabilities


	2022		2023
Deferred tax assets:
Accrued expenses	$	5,445	$	6,178
Lease obligations		14,093		25,574
Alternative minimum tax and general business credits		7,011		7,011
Stock option expense		7,850		11,756
Amazon warrants		16,169		20,002
Other		3,163		6,096
Depreciation and amortization		3,455		4,270
Loss carryforwards		141,381		152,310
Total deferred tax assets		198,567		233,197
Less valuation allowance		(177,224)		(202,242)
Net deferred tax assets		21,343		30,955
Deferred tax liabilities:
Right-of-use assets		(13,950)		(24,650)
Commodity swap contracts		(784)		(741)
Goodwill		(2,847)		(3,160)
Investments in joint ventures and partnerships		(4,862)		(2,989)
Total deferred tax liabilities		(22,443)		(31,540)
Net deferred tax liabilities	$	(1,100)	$	(585)

Schedule of reconciliation of the total amounts of unrecognized tax benefits

The following is a tabular reconciliation of the total amounts of unrecognized tax benefits for the years ended December 31, 2021, 2022 and 2023 (in thousands):


Unrecognized tax benefit—December 31, 2021	$	50,585
Gross increases—tax positions in current year		4,358
Gross increases—tax positions in prior year		—
Gross decreases—tax positions in prior year		(271)
Unrecognized tax benefit—December 31, 2022		54,672
Gross increases—tax positions in current year		4,517
Gross increases—tax positions in prior year		—
Gross decreases—tax positions in prior year		(93)
Unrecognized tax benefit—December 31, 2023	$	59,096

Stockholders' Equity - Fair Value of Amazon Warrant (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Apr. 16, 2021 USD ($) $ / shares shares	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Jun. 14, 2021 $ / shares shares	Apr. 15, 2021 $ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contra revenue charge		$ 60,609	$ 24,302	$ 83,641
Amazon Warrant
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Aggregate number of warrant shares (in shares) \| shares	53,141,755					5,625,959
Total discretionary fuel purchases	$ 500,000
Exercise price of the warrant (in dollars per share) \| $ / shares	$ 13.49					$ 13.49
Exercise price premium (as a percent)	21.30%
Common stock price (in dollars per share) \| $ / shares							$ 11.12
Aggregate number of warrant shares that may require stockholder approval (in shares) \| shares	50,595,531
Contra revenue charge		$ 60,600	$ 24,300	$ 83,600
Customer incentive assets					$ 38,400
Notification period to waive or modify Beneficial Ownership Limitation	61 days
Amazon Warrant \| Black-Scholes option pricing model \| Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	0.000					0.000
Amazon Warrant \| Black-Scholes option pricing model \| Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	0.6646					0.6797
Amazon Warrant \| Black-Scholes option pricing model \| Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	0.0159					0.0149
Amazon Warrant \| Black-Scholes option pricing model \| Expected term in years
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants, Measurement Input	10.0					9.8

Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Disaggregation of revenue

The table below presents the Company’s revenue disaggregated by revenue source (in thousands):


	Year Ended December 31,
	2021		2022		2023
Product revenue:
Volume-related
Fuel sales⁽¹⁾	$	130,973	$	281,103	$	286,956
Change in fair value of derivative instruments⁽²⁾		(3,490)		517		(158)
RIN Credits		31,736		34,635		25,860
LCFS Credits		16,808		12,634		9,885
AFTC ⁽³⁾		20,700		21,760		20,854
Total volume-related product revenue		196,727		350,649		343,397
Station construction sales		16,406		22,346		26,427
Total product revenue		213,133		372,995		369,824
Service revenue:
Volume-related, O&M services		41,934		45,901		52,660
Other services		579		1,268		2,675
Total service revenue		42,513		47,169		55,335
Total revenue	$	255,646	$	420,164	$	425,159

(1)	Includes non-cash stock-based sales incentive contra-revenue charges associated with the Amazon Warrant for the years ended December 31, 2021, 2022 and 2023 of $83.6 million, $24.3 million and $60.6 million, respectively. See Note 13 for more information.

(2)

(3)	Represents AFTC. See Note 1 for more information.

Summary of contract balances

As of December 31, 2022 and 2023, the Company’s contract balances were as follows (in thousands):


	2022		2023
Accounts receivable, net	$	91,430	$	98,426

Contract assets - current	$	6,063	$	7,823
Contract assets - non-current		2,976		2,433
Contract assets - total	$	9,039	$	10,256

Contract liabilities - current	$	5,477	$	4,936
Contract liabilities - non-current		—		151
Contract liabilities - total	$	5,477	$	5,087

Net Income (Loss) Per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Schedule of information required to compute basic and diluted net loss per share

The following table sets forth the computations of basic and diluted earnings (loss) per share for the years ended December 31, 2021, 2022 and 2023 (in thousands, except share and per share amounts):


	2021		2022		2023
Net loss attributable to Clean Energy Fuels Corp.	$	(93,146)	$	(58,733)	$	(99,497)

Weighted-average common shares outstanding		213,118,694		222,414,790		222,904,785
Dilutive effect of potential common shares from restricted stock units, stock options and stock warrants		—		—		—
Weighted-average common shares outstanding - diluted		213,118,694		222,414,790		222,904,785
Basic loss per share	$	(0.44)	$	(0.26)	$	(0.45)
Diluted loss per share	$	(0.44)	$	(0.26)	$	(0.45)

Schedule of potentially dilutive securities that have been excluded from the diluted net loss per share calculations because their effect would have been antidilutive


(in shares)	2021	2022	2023
Stock options	17,153,671	15,456,340	17,825,577
Stonepeak warrant shares	—	—	20,000,000
Restricted stock units	1,126,942	694,945	399,709
Amazon warrant shares	58,767,714	58,767,714	58,767,714
Total	77,048,327	74,918,999	96,993,000

Revenue from Contracts with Customers - Costs to Fulfill a Contract (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Capitalized contract cost, gross	$ 8.9	$ 10.1
Capitalized contract cost, accumulated depreciation	6.9	7.9
Capitalized contract cost, amortization	$ 0.2	$ 0.3	$ 0.5

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 8 —Fair Value Measurements

The Company follows the authoritative guidance for fair value measurements with respect to assets and liabilities that are measured at fair value on a recurring basis and non-recurring basis. Under the standard, fair value is defined as the exit price, or the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants, as of the measurement date. The standard also establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the most observable inputs be used when available. Observable inputs are inputs market participants would use in valuing the asset or liability developed based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the factors market participants would use in valuing the asset or liability developed based upon the best information available in the circumstances. The hierarchy consists of the following

three levels: Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 inputs include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs (other than quoted prices) that are observable for the asset or liability, either directly or indirectly; Level 3 inputs are unobservable inputs for the asset or liability. Categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The Company’s U.S. government issued debt securities are classified within Level 1 because they are valued using the most recent quoted prices for identical assets in active markets. Zero coupon bonds and certificate of deposits are classified within Level 2 because they are valued using the most recent quoted prices for identical assets in markets that are not active and quoted prices for similar assets in active markets.

The Company used the income approach to value its outstanding commodity swap contracts and embedded derivatives in its fueling agreements under the Zero Now truck financing program (see Note 7). Under the income approach, the Company used a discounted cash flow (“DCF”) model in which cash flows anticipated over the term of the contracts are discounted to their present value using an expected discount rate. The discount rate used for cash flows reflects the specific risks in spot and forward rates and credit valuation adjustments. This valuation approach is considered a Level 3 fair value measurement. The significant unobservable inputs used in the fair value measurement of the Company’s derivative instruments are Ultra-Low Sulfur Diesel (“ULSD”) forward prices and differentials from ULSD to Petroleum Administration for Defense District (“PADD”) regions. Significant increases (decreases) in any of those inputs in isolation would result in a significantly lower or higher fair value measurement. Generally, a change in the ULSD forward prices is accompanied by a directionally opposite but less extreme change in the ULSD-PADD differential.

The Company estimated the fair value of its outstanding commodity swap contracts based on the following inputs as of December 31, 2022 and 2023:


	December 31, 2022			December 31, 2023
Significant Unobservable Inputs	Input Range	Weighted Average		Input Range	Weighted Average
ULSD Gulf Coast Forward Curve	$2.35 - $2.59	$	2.48	$ 1.97 - $ 2.27	$	2.15
Historical Differential to PADD 3 Diesel	$0.88 - $1.62	$	1.13	$ 0.92 - $ 1.62	$	1.16
Historical Differential to PADD 5 Diesel	$1.89 - $3.00	$	2.30	$ 1.89 - $ 3.16	$	2.48

The Company estimated the fair value of embedded derivatives in its fueling agreements under the Zero Now truck financing program based on the following inputs as of December 31, 2022 and 2023:


	December 31, 2022			December 31, 2023
Significant Unobservable Inputs	Input Range	Weighted Average		Input Range	Weighted Average
ULSD Gulf Coast Forward Curve	$2.35 - $2.59	$	2.48	$ 1.97 - $ 2.27	$	2.15
Historical Differential to PADD 3 Diesel	$0.88 - $1.62	$	1.13	$ 0.92 - $ 1.62	$	1.16
Historical Differential to PADD 5 Diesel	$1.91 - $3.05	$	2.31	$ 1.89 - $ 3.16	$	2.48

Convertible Promissory Note

In connection with the Company’s loan commitment to a certain equity method investee, the Company was issued a convertible promissory note with a principal balance equal to the amount of drawdown on the loan commitment (see Note 15). The convertible promissory note bears interest at 7% per annum, compounded quarterly, with a maturity date the earlier of May 7, 2024 or upon the occurrence of a triggering event such as change of control or an event of default. The convertible promissory note is classified as available-for-sale and is carried at fair value, which is measured using the income approach. Under the income approach, the Company used a DCF model in which cash flows anticipated over the term of the note are discounted to their present value using an expected discount rate. The discount rate used reflects the

interest rates offered on loans of similar terms and to borrowers of similar credit quality, which are Level 3 inputs. As such, this valuation approach is considered a Level 3 fair value measurement.

The following table provides quantitative information about the significant inputs used to estimate the fair value of the convertible promissory note as of December 31, 2022 and 2023:



Significant Unobservable Inputs	December 31, 2022	December 31, 2023
Risk-free interest rate	4.57%	5.39%
Credit adjustment	8.36%	5.31%
Credit adjusted discount rate	12.93%	10.70%

The above significant unobservable inputs are subject to change based on changes in economic and market conditions. The use of significant unobservable inputs creates uncertainty in the measurement of fair value as of the reporting date. Significant increase or decrease in any of those inputs in isolation would result in a significantly lower or higher fair value measurement. Generally, a change in market interest rates is accompanied by a directionally opposite change in the estimated fair value of fixed-rate debt securities. The Company records changes in the fair value of available-for-sale debt securities in “Unrealized gain (loss) on available-for-sale securities” within other comprehensive income (loss) in the accompanying consolidated statements of comprehensive loss. In addition, because the Company has reduced its equity method investment in the investee to zero but has other investment in the investee such as the convertible promissory note, the remeasurement to fair value is applied to the convertible promissory note’s adjusted carrying balance after the recognition of equity method losses, which is calculated based on the Company’s percentage ownership interest in such other investment.

There were no transfers of assets or liabilities between Level 1, Level 2, and Level 3 of the fair value hierarchy as of December 31, 2022 or 2023.

The following tables provide information by level for assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2022 and 2023 (in thousands):


	December 31, 2022		Level 1		Level 2		Level 3
Assets:
Available-for-sale securities:
U.S. government securities⁽¹⁾	$	64,880	$	64,880	$	—	$	—
Zero coupon bonds⁽¹⁾		74,159		—		74,159		—
Convertible promissory note⁽⁴⁾		1,880		—		—		1,880
Certificates of deposit ⁽¹⁾		530		—		530		—
Embedded derivatives ⁽³⁾		6,755		—		—		6,755
Liabilities:
Commodity swap contracts ⁽²⁾	$	3,845	$	—	$	—	$	3,845


	December 31, 2023		Level 1		Level 2		Level 3
Assets:
Available-for-sale securities:
U.S. government securities⁽¹⁾	$	157,656	$	157,656	$	—	$	—
Convertible promissory note⁽⁴⁾		2,330		—		—		2,330
Certificates of deposit ⁽¹⁾		530		—		530		—
Embedded derivatives ⁽³⁾		4,628		—		—		4,628
Liabilities:
Commodity swap contracts ⁽²⁾	$	1,875	$	—	$	—	$	1,875

(1)	Included in “Short-term investments” in the accompanying consolidated balance sheets. See Note 6 for more information.

(2)	Included in “Derivative liabilities, related party” and “Long-term portion of derivative liabilities, related party” as of December 31, 2022 and in “Derivative liabilities, related party” as of December 31, 2023 in the accompanying consolidated balance sheets. See Note 7 for more information.

(3)	Included in “Prepaid expenses and other current assets” and “Notes receivable and other long-term assets, net” as of December 31, 2022 and 2023 in the accompanying consolidated balance sheets. See Note 7 for more information.

(4)	Included in “Notes receivable and other long-term assets, net” as of December 31, 2022 and in “Other receivables” as of December 31, 2023 in the accompanying consolidated balance sheets.


	Assets:		Assets:		Liabilities:
	Embedded		Convertible		Commodity
	Derivatives		Promissory Note		Swap Contracts
Balance as of December 31, 2021	$	6,776	$	—	$	(4,383)
Settlements, net		—		—		7,761
Total gain (loss)		(21)		(134)		(7,223)
Purchases		—		2,014		—
Balance as of December 31, 2022	$	6,755	$	1,880	$	(3,845)

Balance as of December 31, 2022	$	6,755	$	1,880	$	(3,845)
Settlements, net		—		—		4,858
Total gain (loss)		(2,127)		103		(2,888)
Purchases		—		3,822		—
Equity method investment loss		—		(3,475)		—
Balance as of December 31, 2023	$	4,628	$	2,330	$	(1,875)

Change in unrealized gain (loss) for the year ended December 31, 2022 included in earnings	$	(21)	$	—	$	538
Change in unrealized gain (loss) for the year ended December 31, 2023 included in earnings	$	(2,127)	$	—	$	1,970
Change in unrealized gain (loss) for the year ended December 31, 2022 included in other comprehensive income (loss)	$	—	$	(134)	$	—
Change in unrealized gain (loss) for the year ended December 31, 2023 included in other comprehensive income (loss)	$	—	$	103	$	—

Other Financial Assets and Liabilities

The carrying amounts of the Company’s cash, cash equivalents, receivables and payables approximate fair value due to the short-term nature of those instruments. The carrying amounts of the Company’s debt instruments approximated their respective fair values as of December 31, 2022.

Debt instruments as of December 31, 2023 consisted of the following (in thousands):


	Net Carrying		Estimated
	Amounts		Fair Value
Stonepeak Term Loan	$	260,906	$	253,303
Other Debt		255		255
Total Debt	$	261,161	$	253,558

The fair values of these debt instruments were estimated using a DCF analysis based on imputed interest rates, which are Level 3 inputs. See Note 12 for more information about the Company’s debt instruments.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Schedule II: Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule II: Valuation and Qualifying Accounts

Schedule II - Valuation and Qualifying Accounts


	(In thousands)
	Allowance for		Allowance for
	Credit Losses		Credit Losses
	on Accounts		on Notes
	Receivables		Receivables
Balance as of December 31, 2020	$	1,335	$	4,105
Charges (benefit) to operations		77		650
Deductions		(207)		—
Balance as of December 31, 2021		1,205		4,755
Charges (benefit) to operations		571		744
Deductions		(401)		—
Balance as of December 31, 2022		1,375		5,499
Charges (benefit) to operations		439		1,041
Deductions		(339)		—
Balance as of December 31, 2023	$	1,475	$	6,540

Summary of Significant Accounting Policies - Tourmaline Joint Development (Details) - Tourmaline Joint Development - Tourmaline Oil Corp. $ in Millions	1 Months Ended
	Apr. 30, 2023 CAD ($) item
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Agreement amount \| $	$ 70
Ownership interest (as a percent)	50.00%
Maximum number of CNG fueling stations expect to construct and commission \| item	20
Period for construction and commission of CNG fueling stations	5 years

Fair Value Measurements - Fair Value Recognition - Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended		24 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue from Contract with Customer, Excluding Assessed Tax	Revenue from Contract with Customer, Excluding Assessed Tax
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income [Extensible List]			Revenue from Contract with Customer, Excluding Assessed Tax
Commodity swap contracts
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Beginning Balance	$ (3,845)	$ (4,383)	$ (4,383)
Settlements, net	4,858	7,761
Total gain (loss)	(2,888)	(7,223)
Ending Balance	(1,875)	(3,845)	$ (1,875)
Change in unrealized gain (loss) included in earnings	1,970	$ 538
Embedded derivatives
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Total gain (loss)	(2,127)
Convertible promissory note
Reconciliation of the beginning and ending balances of liabilities measured at fair value using significant unobservable inputs (Level 3)
Total gain (loss)	$ 103

Net Loss Per Share - Anti-dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net Loss Per Share
Anti-dilutive securities (in shares)	96,993,000	74,918,999	77,048,327
Stock options
Net Loss Per Share
Anti-dilutive securities (in shares)	17,825,577	15,456,340	17,153,671
Convertibles notes
Net Loss Per Share
Anti-dilutive securities (in shares)	20,000,000
Restricted stock units
Net Loss Per Share
Anti-dilutive securities (in shares)	399,709	694,945	1,126,942
Amazon warrant shares
Net Loss Per Share
Anti-dilutive securities (in shares)	58,767,714	58,767,714	58,767,714

Concentrations (Details) - Minimum - Natural gas expense - Supplier concentration	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Three supplier
Supplier Concentrations
Concentration risk, percentage			10.00%
Zero supplier
Supplier Concentrations
Concentration risk, percentage		10.00%
One supplier
Supplier Concentrations
Concentration risk, percentage	10.00%

Cash, Cash Equivalents and Restricted Cash

12 Months Ended

Dec. 31, 2023

Cash and Cash Equivalents [Abstract]

Cash, Cash Equivalents and Restricted Cash

Note 5 —Cash, Cash Equivalents and Restricted Cash

Cash, cash equivalents and restricted cash as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Current assets:
Cash and cash equivalents	$	123,950	$	104,944
Restricted cash - standby letter of credit		2,000		2,019
Total cash, cash equivalents and current portion of restricted cash	$	125,950	$	106,963

Total cash, cash equivalents and restricted cash	$	125,950	$	106,963

The Company considers all highly liquid investments with maturities of three months or less on the date of acquisition to be cash equivalents.

The Company places its cash and cash equivalents with high credit quality financial institutions. At times, such investments may be in excess of the Federal Deposit Insurance Corporation (“FDIC”) and Canadian Deposit Insurance Corporation (“CDIC”) limits. Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash deposits. The amounts in excess of FDIC and CDIC limits were approximately $124.8 million and $105.6 million as of December 31, 2022 and 2023, respectively.

The Company classifies restricted cash as short-term and a current asset if the cash is expected to be used in operations within a year or to acquire a current asset. Otherwise, the restricted cash is classified as long-term. The Company deposited $2.0 million, in the form of a certificate of deposit, at PlainsCapital Bank as collateral for the standby letter of credit issued to Chevron Products Company, a division of Chevron U.S.A. Inc., in connection with the Company’s Adopt-A-Port program. The $2.0 million certificate of deposit is classified as short-term restricted cash and a current asset and is included in “Cash, cash equivalents and current portion of restricted cash” in the accompanying consolidated balance sheets as of December 31, 2022 and 2023.

Derivative Instruments and Hedging Activities - Narrative (Details) - Not Designated as Hedging Instrument - Commodity swaps gal in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2018 contract gal	Dec. 31, 2023 $ / gal gal	Dec. 31, 2022 $ / gal gal
Derivative [Line Items]
Derivative asset, number of instruments held \| contract	2
Volumes (Diesel Gallons) \| gal	5.0	1.9	6.9
Weighted-average price per diesel gallon (in usd per gallon) \| $ / gal		3.18	3.18

Leases

12 Months Ended

Dec. 31, 2023

Leases

Leases

Note 16 —Leases

The Company’s operating leases are related to real estate for fueling stations, office spaces, warehouses, a LNG liquefaction plant, and office equipment, and its finance leases are primarily related to vehicles.

NG Advantage has provided residual value guarantees on leases of certain vehicles aggregating $1.0 million to the lessors. NG Advantage expects to owe these amounts in full and therefore they have been included in the measurement of the lease liabilities and ROU assets.

Certain of the Company’s real estate leases contain variable lease payments, including payments based on a change in the index or gasoline gallon equivalents of natural gas dispensed at fueling stations. These variable lease payments cannot be determined at the commencement of the lease and are not included in the ROU assets and lease liabilities. As such, amounts associated with these variable lease payments are recorded as a period expense when incurred.

Lessee Accounting

As of December 31, 2022 and 2023, the Company’s finance and operating lease asset and liability balances were as follows (in thousands):


	2022		2023
Finance leases:
Land, property and equipment, gross	$	5,703	$	6,436
Accumulated depreciation		(2,895)		(3,199)
Land, property and equipment, net	$	2,808	$	3,237

Current portion of finance lease obligations	$	948	$	1,758
Long-term portion of finance lease obligations		2,134		1,839
Total finance lease liabilities	$	3,082	$	3,597

Operating leases:
Operating lease right-of-use assets	$	52,586	$	92,324

Current portion of operating lease obligations	$	4,206	$	6,687
Long-term portion of operating lease obligations		48,911		89,065
Total operating lease liabilities	$	53,117	$	95,752

The components of lease expense for finance and operating leases consisted of the following (in thousands):


	Year Ended December 31,
	2022		2023
Finance leases:
Depreciation on assets under finance leases	$	877	$	928
Interest on lease liabilities		164		183
Total finance leases expense	$	1,041	$	1,111

Operating leases:
Lease expense	$	8,800	$	15,986
Lease expense on short-term leases		513		503
Variable lease expense		4,306		4,777
Sublease income		(636)		(636)
Total operating leases expense	$	12,983	$	20,630

Supplemental information on finance and operating leases is as follows (dollars in thousands):


	Year Ended December 31,
	2022		2023
Operating cash outflows from finance leases	$	164	$	183
Operating cash outflows from operating leases	$	6,582	$	10,709
Financing cash outflows from finance leases	$	945	$	1,055

Assets obtained in exchange for new finance lease liabilities ⁽¹⁾	$	774	$	1,569
ROU assets obtained in exchange for operating lease liabilities ⁽¹⁾	$	13,449	$	46,592


	December 31,	December 31,
	2022	2023
Weighted-average remaining lease term - finance leases	2.34 years	2.44 years
Weighted-average remaining lease term - operating leases	11.29 years	10.14 years

Weighted-average discount rate - finance leases	5.71%	7.41%
Weighted-average discount rate - operating leases	8.44%	9.82%

(1)	These amounts are excluded from the accompanying consolidated statements of cash flows as they are non-cash investing, operating and/or financing activities.

The following schedule presents the Company’s maturities of finance and operating lease liabilities as of December 31, 2023 (in thousands):


Fiscal Year	Finance Leases		Operating Leases
2024	$	1,979	$	15,125
2025		1,073		15,406
2026		593		15,363
2027		362		15,359
2028		3		14,531
Thereafter		—		75,759
Total minimum lease payments		4,010		151,543
Less amount representing interest		(413)		(55,791)
Present value of lease liabilities	$	3,597	$	95,752

Lessor Accounting

The Company leases fueling station equipment to customers pursuant to agreements that contain an option to extend and an end-of-term purchase option. Receivables from these leases are accounted for as finance leases, specifically sales-type leases, and are included in “Other receivables” and “Notes receivable and other long-term assets, net” in the accompanying consolidated balance sheets.

The Company recognizes the net investment in the lease as the sum of the lease receivable and the unguaranteed residual value, both of which are measured at the present value using the interest rate implicit in the lease.

During the years ended December 31, 2021, 2022 and 2023, the Company recognized $0.4 million, $0.4 million and $0.4 million, respectively, in “Interest income” on its lease receivables.

The following schedule presents the Company’s maturities of lease receivables as of December 31, 2023 (in thousands):


Fiscal Year:
2024	$	962
2025		962
2026		985
2027		1,105
2028		515
Thereafter		703
Total minimum lease payments		5,232
Less amount representing interest		(1,087)
Present value of lease receivables	$	4,145

Revenue from Contracts with Customers - Remaining Performance Obligations (Details) $ in Millions	Dec. 31, 2023 USD ($)
Remaining Performance Obligations
Revenue, remaining performance obligation, amount	$ 24.5
Minimum
Remaining Performance Obligations
Revenue, remaining performance obligation, expected timing of satisfaction, period	12 months
Maximum
Remaining Performance Obligations
Revenue, remaining performance obligation, expected timing of satisfaction, period	24 months

Stockholders' Equity - Amazon Warrant Activity (Details) - Amazon Warrant - USD ($)			12 Months Ended
	Jun. 14, 2021	Apr. 16, 2021	Dec. 31, 2023
Class of Warrant or Right [Line Items]
Outstanding and unvested Beginning Balance			$ 42,314,667
Granted			0
Vested			(4,701,632)
Outstanding and unvested as of Ending Balance			$ 37,613,035
Number of warrants vested			4,701,632
Vesting over the first year
Class of Warrant or Right [Line Items]
Vested	(1,406,490)	(13,283,445)
Number of warrants vested	1,406,490	13,283,445

Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of short-term investments

Short-term investments as of December 31, 2022 consisted of the following (in thousands):


			Gross
	Amortized		Unrealized		Estimated
	Cost		Gain (Loss)		Fair Value
Zero coupon bonds	$	74,524	$	(365)	$	74,159
U.S. government securities		64,861		19		64,880
Certificates of deposit		530		—		530
Total short-term investments	$	139,915	$	(346)	$	139,569

Short-term investments as of December 31, 2023 consisted of the following (in thousands):


			Gross
	Amortized		Unrealized		Estimated
	Cost		Gain (Loss)		Fair Value
U.S. government securities	$	157,628	$	28	$	157,656
Certificates of deposit		530		—		530
Total short-term investments	$	158,158	$	28	$	158,186

Stockholders' Equity - Share Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended			34 Months Ended
	Jun. 13, 2018	May 09, 2018	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 07, 2021	Mar. 12, 2020
Subsidiary, Sale of Stock [Line Items]
Approved share repurchase program							$ 50,000	$ 30,000
Cost to repurchase common stock			$ 175	$ 6,122	$ 2,916
Repurchase of common stock (in shares)			0
Stock repurchase program total stock repurchased						9,387,340
Amount utilized under the repurchase plan						$ 23,500
Authorized funds remaining under the Repurchase Program				$ 26,500		$ 26,500
Purchase Agreement
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares)	50,856,296	50,856,296
Price per share (in dollars per share)		$ 1.64
Percentage of ownership after transaction	25.00%
Consideration received on transaction	$ 83,400
Purchase Agreement \| Purchase Percentage Covenant, Threshold
Subsidiary, Sale of Stock [Line Items]
Percentage of ownership after transaction		5.00%
Purchase Agreement \| Purchase Percentage Covenant, Maximum
Subsidiary, Sale of Stock [Line Items]
Percentage of ownership after transaction		30.00%

Leases - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Leases - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Sales-type lease, interest income	$ 0.4	$ 0.4	$ 0.4
NG Advantage [Member]
Lessee, Lease, Description [Line Items]
Residual value of leased asset	$ 1.0

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Subsidiary, Sale of Stock [Line Items]

Summary of compensation expense and related income tax benefit related to the stock-based compensation expense recognized

The following table summarizes the compensation expense and related income tax benefit related to the Company’s stock-based compensation arrangements recognized in the accompanying consolidated statements of operations during the periods presented (in thousands):


	Year Ended December 31,
	2021		2022		2023
Stock-based compensation expense, net of $0 tax in 2021, 2022 and 2023	$	14,994	$	26,473	$	23,336

Summary of the Company's RSU activity

The following table summarizes the Company’s Service-Based RSU activities for the year ended December 31, 2023:


		Weighted
		Average
	Number of	Fair Value at
	Shares	Grant Date
RSU outstanding and unvested as of December 31, 2022	694,945	$	8.41
Granted	129,524	$	4.19
Vested	(418,274)	$	7.38
Forfeited or expired	(6,486)	$	10.08
RSU outstanding and unvested as of December 31, 2023	399,709	$	8.10

Amazon Warrant

Subsidiary, Sale of Stock [Line Items]

Schedule of fair value measurement of warrants


	April 16, 2021	June 14, 2021
Dividend yield	0.0%	0.0%
Expected volatility	66.46%	67.97%
Risk-free interest rate	1.59%	1.49%
Expected term in years	10.0	9.8

Schedule of warrant activity

The following table summarizes the Amazon Warrant activities for the year ended December 31, 2023:


		Warrant
		Shares
Outstanding and unvested as of December 31, 2022		42,314,667
Granted		—
Vested		(4,701,632)
Outstanding and unvested as of December 31, 2023		37,613,035

Stonepeak Warrant

Subsidiary, Sale of Stock [Line Items]

Schedule of fair value measurement of warrants


	December 12, 2023	December 12, 2023
Exercise price	5.50	6.50
Dividend yield	0.0%	0.0%
Expected volatility	72.96%	72.96%
Risk-free interest rate	4.22%	4.22%
Expected term in years	8.5	8.5

Schedule of warrant activity


		Warrant
		Shares
Outstanding and unexercised as of December 31, 2022		—
Granted		20,000,000
Exercised		—
Outstanding and unexercised as of December 31, 2023		20,000,000

Service Based Stock Options [Member]

Subsidiary, Sale of Stock [Line Items]

Summary of stock option activity

The following table summarizes the Company’s service-based stock option activities for the year ended December 31, 2023:


				Weighted
				Average
		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
	Number of	Exercise		Term	Value
	Shares	Price		(in years)	(in thousands)
Options outstanding as of December 31, 2022	10,116,340	$	6.00
Granted	3,030,439	$	4.78
Exercised	(98,592)	$	2.38
Forfeited or expired	(487,610)	$	7.29
Options outstanding as of December 31, 2023	12,560,577	$	5.68	6.71	$	5,369
Options exercisable as of December 31, 2023	8,117,695	$	5.54	5.63	$	5,345
Options vested and expected to vest as of December 31, 2023	12,560,577	$	5.68	6.71	$	5,369

Schedule of assumptions used to estimate the fair value of each award using the Black-Scholes option pricing model

The fair value of each service-based stock option granted was estimated as of the date of grant using the Black-Scholes option pricing model and using the following assumptions:


	Year Ended December 31,
	2021	2022	2023
Dividend yield	0.0%	0.0%	0.0%
Expected volatility	76.8% to 96.8%	73.7% to 76.9%	75.2% to 76.6%
Risk-free interest rate	0.58% to 1.31%	1.52% to 4.34%	3.68% to 4.73%
Expected life in years	5.6 to 5.8	5.6 to 5.9	5.9 to 6.2

Performance-Based Stock Options [Member]

Subsidiary, Sale of Stock [Line Items]

Summary of stock option activity

The following table summarizes the Company’s performance-based stock option activities for the year ended December 31, 2023:


				Weighted
				Average
		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
	Number of	Exercise		Term	Value
	Shares	Price		(in years)	(in thousands)
Options outstanding as of December 31, 2022	1,640,000	$	6.77
Granted	—	$	—
Exercised	—	$	—
Forfeited or expired	(25,000)	$	6.77
Options outstanding as of December 31, 2023	1,615,000	$	6.77	7.94	$	—
Options vested and exercisable as of December 31, 2023	403,750	$	6.77	7.94	$	—

Schedule of assumptions used to estimate the fair value of each award using the Black-Scholes option pricing model

The fair value of each performance-based stock option granted was estimated as of the date of grant using the Black-Scholes option pricing model and using the following assumptions:



		December 7, 2021
Dividend yield		0.0%
Expected volatility		77.1%
Risk-free interest rate		1.36%
Expected life in years		6.2

Market Based Stock Options [Member]

Subsidiary, Sale of Stock [Line Items]

Summary of stock option activity

The following table summarizes the Company’s market-based stock option activities for the year ended December 31, 2023:


				Weighted
				Average
		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
	Number of	Exercise		Term	Value
	Shares	Price		(in years)	(in thousands)
Options outstanding as of December 31, 2022	3,700,000	$	6.77
Granted	—	$	—
Exercised	—	$	—
Forfeited or expired	(50,000)	$	6.77
Options outstanding as of December 31, 2023	3,650,000	$	6.77	7.94	$	—
Options vested and exercisable as of December 31, 2023	—	$	—	—	$	—

Schedule of assumptions used to estimate the fair value of each award using the Black-Scholes option pricing model



		December 7, 2021
Dividend yield		0.0%
Expected volatility		67.8%
Risk-free interest rate		1.5%
Expected life in years		10.0

Derivative Instruments and Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Summary of commodity derivative activity

Commodity swaps and embedded derivatives as of December 31, 2022 consisted of the following (in thousands):


	Gross Amounts		Gross Amounts		Net Amount
	Recognized		Offset		Presented
Assets:
Fueling agreements:
Prepaid expenses and other current assets	$	1,640	$	—	$	1,640
Notes receivable and other long-term assets, net		5,115		—		5,115
Total derivative assets	$	6,755	$	—	$	6,755
Liabilities:
Commodity swaps:
Current portion of derivative liabilities, related party	$	2,415	$	—	$	2,415
Long-term portion of derivative liabilities, related party		1,430		—		1,430
Total derivative liabilities	$	3,845	$	—	$	3,845

Commodity swaps and embedded derivatives as of December 31, 2023 consisted of the following (in thousands):


	Gross Amounts		Gross Amounts		Net Amount
	Recognized		Offset		Presented
Assets:
Fueling agreements:
Prepaid expenses and other current assets	$	2,593	$	—	$	2,593
Notes receivable and other long-term assets, net		2,035		—		2,035
Total derivative assets	$	4,628	$	—	$	4,628
Liabilities:
Commodity swaps:
Current portion of derivative liabilities, related party	$	1,875	$	—	$	1,875
Total derivative liabilities	$	1,875	$	—	$	1,875

Schedule of weighted-average price of open commodity swap contract

The following table reflects the weighted-average price of open commodity swap contracts as of December 31, 2022 and 2023, by year with associated volumes:


	December 31, 2022			December 31, 2023
	Volumes	Weighted-Average Price per		Volumes	Weighted-Average Price per
Year	(Diesel Gallons)	Diesel Gallon		(Diesel Gallons)	Diesel Gallon
2023	5,000,000	$	3.18	—	$	—
2024	1,875,000	$	3.18	1,875,000	$	3.18

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income tax expense	$ (423)	$ 220	$ 119
Income tax benefit	423	(220)	(119)
Tax benefit	59,096	54,672	50,585
Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Impact of Warrants, Amount	$ 5,381	$ 1,134	$ 3,707

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Derivative Instruments and Hedging Activities - Schedule of Weighted-Average Price of Open Commodity Swap Contracts (Details) - Not Designated as Hedging Instrument	12 Months Ended
	Dec. 31, 2023 $ / gal gal	Dec. 31, 2022 $ / gal gal
Commodity Swap 2023
Derivative [Line Items]
Volumes (Diesel Gallons) \| gal	0	5,000,000
Weighted-Average Price per Diesel Gallon (in usd per gallon) \| $ / gal	0	3.18
Commodity Swap 2024
Derivative [Line Items]
Volumes (Diesel Gallons) \| gal	1,875,000	1,875,000
Weighted-Average Price per Diesel Gallon (in usd per gallon) \| $ / gal	3.18	3.18

Land, Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Land, Property and Equipment
Land, property and equipment, gross	$ 823,898	$ 721,912
Less accumulated depreciation	(492,140)	(457,844)
Total land, property and equipment, net	331,758	264,068
Capitalized software costs, net	36,800	35,300
Accumulated amortization on the capitalized software costs	34,000	32,100
Amortization expense related to the capitalized software costs	1,900	1,700	$ 1,600
Amount included in accounts payable balances	10,200	12,900
Land
Land, Property and Equipment
Land, property and equipment, gross	7,397	3,476
LNG liquefaction plants
Land, Property and Equipment
Land, property and equipment, gross	96,786	94,790
Station equipment
Land, Property and Equipment
Land, property and equipment, gross	418,647	353,104
Trailers
Land, Property and Equipment
Land, property and equipment, gross	70,542	73,253
Other equipment
Land, Property and Equipment
Land, property and equipment, gross	105,137	106,184
Construction in progress
Land, Property and Equipment
Land, property and equipment, gross	125,389	$ 91,105
Pickens Plant
Land, Property and Equipment
Insurance Recoveries	$ 3,900

Insider Trading Arrangements - Andrew Littlefair Trading Plan - Andrew J. Littlefair	12 Months Ended
	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Rule 10b5-1 Plan Elections On November 22, 2023, Andrew J. Littlefair, Chief Executive Officer, adopted a Rule 10b5-1 trading plan for the purpose of establishing a sales plan of the Company’s common stock that is intended to comply with the requirements of Rule 10b5-1(c)(1) under the Securities Exchange Act of 1934, as amended. Mr. Littlefair’s Rule 10b5-1 trading plan is in effect from March 15, 2024 to the earlier of (1) December 31, 2024 and (2) the date on which an aggregate of 450,000 shares of the Company’s common stock have been sold pursuant to the Rule 10b5-1 trading plan.
Name	Andrew J. Littlefair
Title	Chief Executive Officer
Rule 10b5-1 Arrangement Adopted	true
Non-Rule 10b5-1 Arrangement Adopted	true
Adoption Date	November 22, 2023
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Aggregate Available	450,000

Commitments and Contingencies - Long-Term Take-or-Pay Natural Gas Purchase Contracts (Details) - USD ($) $ in Millions	Dec. 31, 2023	Sep. 30, 2023	Nov. 07, 2022
Loan Commitment to an Equity Method Investee
Fixed commitments under the contract payable in future
Irrevocably committed amount		$ 5.5	$ 5.5
Interest rate			7.00%
Convertible promissory note
Fixed commitments under the contract payable in future
Interest rate	7.00%
Natural Gas Supply Agreement \| DGS
Fixed commitments under the contract payable in future
2024	$ 13.2

Investments in Other Entities and Noncontrolling Interest in a Subsidiary - bp Joint Venture (Details) - USD ($) $ in Thousands, shares in Millions					12 Months Ended
	Dec. 28, 2023	Dec. 20, 2023	Jun. 21, 2021	Apr. 13, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 18, 2020
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments					$ (12,510)	$ (4,824)	$ (430)
BP Products North America \| bp Loan
Schedule of Equity Method Investments [Line Items]
Debt issuance amount								$ 50,000
bpJV \| ADG RNG Production Facilities
Schedule of Equity Method Investments [Line Items]
Investment commitment in joint venture			$ 50,200	$ 30,000
Additional commitment in joint venture				20,000
Initial contribution commitment				$ 30,000
Contribution to joint venture	$ 67,950
Ownership interest (as a percent)					50.00%
Income (loss) from equity method investments					$ (4,400)	(2,700)	$ (400)
Investment balance					$ 220,300	$ 156,800
bpJV \| ADG RNG Production Facilities \| Class A Units
Schedule of Equity Method Investments [Line Items]
Number of units received				30.0
Payments to acquire units in joint venture			20,000
Priority Return to acquire additional units			$ 200
bpJV \| ADG RNG Production Facilities \| bp
Schedule of Equity Method Investments [Line Items]
Investment commitment in joint venture				$ 50,000
Ownership interest (as a percent)					50.00%
bpJV \| ADG RNG Production Facilities \| bp \| Class A Units
Schedule of Equity Method Investments [Line Items]
Number of units received				30.0
bpJV \| ADG RNG Production Facilities \| bp \| Class B Units
Schedule of Equity Method Investments [Line Items]
Number of units received				20.0
bpJV \| bpJV \| ADG RNG Production Facilities
Schedule of Equity Method Investments [Line Items]
Contribution to joint venture		$ 135,900

Divestitures

12 Months Ended

Dec. 31, 2023

Business Combinations [Abstract]

Divestitures

Note 3 —Divestitures

bp Transaction

On February 27, 2017, Clean Energy Renewable Fuels (“Renewables”) entered into an asset purchase agreement (the “APA”) with BP Products North America, Inc. (“bp”). Pursuant to the APA, Renewables agreed to sell to bp its assets

relating to its RNG production business (the “bp Transaction”), consisting of Renewables’ two RNG production facilities, Renewables’ interest in joint ventures formed with a third-party to develop new RNG production facilities, and Renewables’ third-party RNG supply contracts (the “Assets”).

Under the APA, bp was required, following the closing of the bp Transaction, to pay Renewables up to an additional $25.0 million in cash over a five-year period if certain conditions relating to the Assets were met. In February 2018, the Company received $0.9 million in cash for its satisfaction of the performance criteria for the first period under the APA, which ended on December 31, 2017. Upon its receipt of such cash, the Company paid $0.1 million in cash and issued 15,877 shares of the Company’s common stock with a fair value of $0.0 million to former holders of options to purchase membership units in Renewables. The performance criteria for the second period under the APA, which ended on December 31, 2018, was also satisfied, and the Company received a cash payment of $5.4 million in March 2019. During the year ended December 31, 2019, after receipt of the cash payment, the Company paid $0.6 million in cash to former holders of options to purchase membership units in Renewables. In December 2019, the Company and bp entered into an Amendment to the APA (“Amended APA”) which amended the earn-out for years four and five and paid the Company an additional $2.8 million for year three of the earn-out period. As a result of the performance criteria for year three under the APA being satisfied, and the additional $2.8 million received by the Company in December 2019 in accordance with the Amended APA, the Company recognized a gross gain of $8.4 million and accrued amounts due to former holders of options to purchase membership units in Renewables of $0.9 million as of December 31, 2019. During the year ended December 31, 2020, the Company recognized a gross gain of $1.0 million and accrued amounts due to former holders of options to purchase membership units in Renewables of $0.1 million as a result of the performance criteria being satisfied for year four under the Amended APA. During the year ended December 31, 2021, the Company recognized a gross gain of $4.4 million and accrued amounts due to former holders of options to purchase membership units in Renewables of $0.5 million as a result of the performance criteria being satisfied for year five under the Amended APA, representing the final earnout payment under the Amended APA. The Company recognized a net gain of $7.5 million, $1.1 million, and $3.9 million during the years ended December 31, 2019, 2020 and 2021, respectively, which is included in “Gain from sale of certain assets of subsidiary” in the accompanying consolidated statements of operations.

In connection with the bp Transaction, the Company paid $10.3 million in cash and issued 770,269 shares of the Company’s common stock with a fair value of $2.0 million to former holders of options to purchase membership units in Renewables.

Following the completion of the bp Transaction, Renewables and the Company continue to procure RNG from bp under a long-term supply contract (the “bp Supply Agreement”) and from other RNG suppliers and resell such RNG through the Company’s fueling infrastructure. On October 1, 2018, Renewables and bp amended the bp Supply Agreement to extend the term and add additional RNG supply. bp and Renewables share in the RINs and LCFS Credits generated from the increased RNG supply sold through the Company’s vehicle fueling infrastructure and to other customers. See Note 1 for information on revenue recognition of these credits.

Stockholders' Equity - Performance-Based Stock Options (Details) - Performance-Based Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Dec. 07, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-based compensation
Contractual term		10 years
Number of Shares
Outstanding at the beginning of the period (in shares)		1,640,000
Granted (in shares)		0	1,640,000
Exercised (in shares)		0
Forfeited or expired (in shares)		(25,000)
Outstanding at the end of the period (in shares)		1,615,000	1,640,000
Exercisable at the end of the period (in shares)		403,750
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)		$ 6.77
Granted (in dollars per share)		0
Exercised (in dollars per share)		0
Forfeited or expired (in dollars per share)		6.77
Outstanding at the end of the period (in dollars per share)		6.77	$ 6.77
Exercisable at the end of the period (in dollars per share)		$ 6.77
Additional option disclosures
Outstanding at the end of the period, weighted average remaining contractual term		7 years 11 months 8 days
Exercisable at the end of the period, weighted average remaining contractual term		7 years 11 months 8 days
Outstanding at the end of the period, aggregate intrinsic value		$ 0
Exercisable at the end of the period, aggregate intrinsic value		0
Total unrecognized compensation cost related to non-vested shares		$ 4,100
Number of shares vested		0
Total fair value of shares vested		$ 0
Weighted-average assumption used for grants
Dividend yield	0.00%
Expected volatility	77.10%
Risk-free interest rate	1.36%
Expected life	6 years 2 months 12 days
Stock-based compensation
Weighted-average grant date fair values of options granted (in dollars per share)		$ 4.58
Exercised during the period, aggregate intrinsic value		$ 0
Stock-based compensation expense		$ 400	$ 2,000	$ 1,000

Debt - Riverstone Credit Agreement (Details) - USD ($)			12 Months Ended
Debt - Riverstone Credit Agreement (Details) - USD ($)	Dec. 12, 2023	Dec. 22, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Interest expense			$ 22,924,000	$ 6,308,000	$ 4,430,000
Riverstone Credit Agreement \| Term loan
Debt Instrument [Line Items]
Proceeds from loan		$ 150,000,000
Debt Repayment	$ 150,000,000.0
Interest expense	$ 5,400,000
Riverstone Credit Agreement \| Term loan \| Elected under SOFR
Debt Instrument [Line Items]
Applicable margin (as a percent)		7.25%
Floor rate (as a percent)		1.50%
Riverstone Credit Agreement \| Term loan \| Elected under ABR
Debt Instrument [Line Items]
Applicable margin (as a percent)		6.25%
Floor rate (as a percent)		2.50%
Riverstone Credit Agreement \| Term loan \| 1 year to 18 months
Debt Instrument [Line Items]
Call premium (as a percent)		2.00%
Riverstone Credit Agreement \| Term loan \| 18 months to 24 months
Debt Instrument [Line Items]
Call premium (as a percent)		2.50%
Riverstone Credit Agreement \| Term loan \| Thereafter
Debt Instrument [Line Items]
Call premium (as a percent)		3.00%
Riverstone Credit Agreement \| Term loan \| Federal Funds
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Riverstone Credit Agreement \| Term loan \| SOFR
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
Applicable margin (as a percent)		6.50%
Riverstone Credit Agreement \| Term loan \| ABR
Debt Instrument [Line Items]
Interest rate (as a percent)		5.50%

Accrued Liabilities

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Accrued Liabilities

Note 11 —Accrued Liabilities

Accrued liabilities as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Accrued alternative fuels incentives ⁽¹⁾	$	34,239	$	41,609
Accrued employee benefits		5,128		5,315
Accrued gas and equipment purchases		22,008		17,485
Accrued interest		1,827		1,451
Accrued property and other taxes		3,782		4,502
Accrued salaries and wages		6,857		8,697
Other ⁽²⁾		16,238		12,475
Total accrued liabilities	$	90,079	$	91,534

(1)	Includes amount for RINs, LCFS Credits, and AFTC payable to third parties.

(2)	No individual item in “Other” exceeds 5% of total current liabilities.

401(k) Plan (Details) - USD ($) $ in Millions	12 Months Ended
401(k) Plan (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Maximum percentage of base pay that can be contributed by employees through salary deferrals	90.00%
Contribution by the company	$ 1.7	$ 1.9	$ 1.6

Stockholders' Equity - Employee Stock Purchase Plan (Details) - Employee Stock Purchase Plan $ in Millions		12 Months Ended
	May 07, 2013 period shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	May 07, 2022 shares
Stock-based compensation
Purchase price of shares expressed as percentage of fair market value of common stock	85.00%
Number of non-concurrent offering periods \| period	2
Number of shares available for future grant					2,500,000
Number of shares reserved (in shares)	2,500,000
Stock-based compensation expense \| $		$ 0.1	$ 0.1	$ 0.1
Shares sold pursuant to the ESPP (in shares)		102,666

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Stockholders' Equity

12 Months Ended

Dec. 31, 2023

Stockholders' Equity Note [Abstract]

Stockholders' Equity

Note 13 —Stockholders’ Equity

Authorized Shares

The Company’s certificate of incorporation authorizes the issuance of two classes of capital stock designated as common stock and preferred stock, each having $0.0001 par value per share. On June 14, 2021, the Company’s stockholders approved an increase in the number of shares of Common Stock the Company is authorized to issue from 304,000,000 to 454,000,000. As of December 31, 2023, the Company is authorized to issue 455,000,000 shares, of which 454,000,000 shares of capital stock are designated common stock and 1,000,000 shares are designated preferred stock.

Dividend Provisions

The Company did not declare or pay any dividends during the years ended December 31, 2021, 2022 and 2023.

Voting Rights

Each holder of common stock has the right to one vote per share owned on matters presented for stockholder action.

TotalEnergies Private Placement

On May 9, 2018, the Company entered into a stock purchase agreement (the “Purchase Agreement”) with TotalEnergies Marketing Services, S.E. (“TMS”), a wholly owned subsidiary of TotalEnergies. Pursuant to the Purchase Agreement, the Company agreed to sell and issue, and TMS agreed to purchase, up to 50,856,296 shares of the Company’s common stock at a purchase price of $1.64 per share, all in a private placement (the “TotalEnergies Private Placement”). The purchase price per share was determined based on the volume-weighted average price for the Company’s common stock between March 23, 2018 (the day on which discussions began between the Company and TotalEnergies) and May 3, 2018 (the day on which the Company agreed in principle with TotalEnergies regarding the structure and basic terms of its investment). As of the date of the Purchase Agreement, TotalEnergies did not hold or otherwise beneficially own any shares of the Company’s common stock, and TotalEnergies has agreed, until the later of May 9, 2020 or such date when it ceases to hold more than 5.0% of the Company’s common stock then outstanding, among other similar undertakings and subject to customary conditions and exceptions, to not purchase shares of the Company’s common stock or otherwise

pursue transactions that would result in TotalEnergies beneficially owning more than 30.0% of the Company’s equity securities without the approval of the Company’s board of directors.

On June 13, 2018, the Company and TMS closed the TotalEnergies Private Placement, in which: (1) the Company issued to TMS all of the 50,856,296 shares of its common stock issuable under the Purchase Agreement, resulting in TotalEnergies beneficially holding approximately 25.0% of the outstanding shares of the Company’s common stock and the largest ownership position of the Company as of September 30, 2018; (2) TotalEnergies paid to the Company an aggregate of $83.4 million in gross proceeds, which the Company has used and expects to continue to use for working capital and general corporate purposes, which may include executing its business plans, pursuing opportunities for further growth, and retiring a portion of its outstanding indebtedness; and (3) the Company and TotalEnergies entered into a registration rights agreement, described below. In connection with the issuance of common stock, the Company incurred transaction fees of $1.9 million.

Pursuant to the Purchase Agreement, the Company and TotalEnergies also entered into a registration rights agreement on June 13, 2018, upon the closing under the Purchase Agreement. Pursuant to the registration rights agreement, the Company filed a registration statement with the Securities and Exchange Commission to cover the resale of the shares issued and sold under the Purchase Agreement, which was declared effective on August 16, 2018, and is obligated to use its commercially reasonable efforts to maintain the effectiveness of such registration statement until all such shares are sold or may be sold without restriction under Rule 144 under the Securities Act of 1933, as amended. As of December 31, 2023, the Company was in compliance with all of its registration covenants set forth in the registration rights agreement.

At-The-Market Offerings

On May 10, 2021, the Company entered into an equity distribution agreement with Goldman Sachs & Co. LLC, as sales agent, to sell shares of the Company’s common stock having an aggregate offering price of up to $100.0 million in an at-the-market offering program (the “May ATM Program”). Through June 3, 2021, the Company sold 12,362,237 shares of common stock under the May ATM Program, which exhausted the May ATM Program. On June 7, 2021, the Company entered into a new equity distribution agreement with Goldman Sachs & Co. LLC, as sales agent, to sell additional shares of common stock having an aggregate offering price of up to $100.0 million in a new at-the-market offering program (the “June ATM Program” and, together with the May ATM Program, the “ATM Programs”). On June 8, 2021, the Company sold 10,473,946 shares of common stock under the June ATM Program which exhausted the June ATM Program.

For the year ended December 31, 2021, the Company issued 22,836,183 shares of common stock under the ATM Programs for gross proceeds of $200.0 million, and incurred transaction costs of $6.5 million, including $6.0 million in commissions paid to Goldman Sachs & Co. LLC.

Share Repurchase Program

On March 12, 2020, the Company’s Board of Directors approved a share repurchase program of up to $30.0 million (exclusive of fees and commissions) of the Company’s outstanding common stock (the “Repurchase Program”). On December 7, 2021, the Company’s Board of Directors approved an increase in the aggregate purchase amount under the Repurchase Program from $30.0 million to $50.0 million (exclusive of fees and commissions). The Repurchase Program does not have an expiration date, and it may be suspended or discontinued at any time. During the year ended December 31, 2023, there were no repurchases of the Company’s common stock under the Repurchase Program. As of December 31, 2023, the Company has utilized a total of $23.5 million under the Repurchase Program from its inception to repurchase 9,387,340 shares of common stock, and a total of $26.5 million of authorized funds remain available for common stock repurchase under the Repurchase Program. The Repurchase Program does not obligate the Company to acquire any specific number of shares. Repurchases under the Repurchase Program may be effected from time to time through open market purchases, privately negotiated transactions, structured or derivative transactions, including accelerated share repurchase transactions, or other methods of acquiring shares, in each case subject to market conditions, applicable

securities laws and other relevant factors. Repurchases may also be made under plans complying with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended.

Stock-Based Compensation


	Year Ended December 31,
	2021		2022		2023
Stock-based compensation expense, net of $0 tax in 2021, 2022 and 2023	$	14,994	$	26,473	$	23,336

Equity Incentive Plans

In December 2006, the Company adopted its 2006 Equity Incentive Plan (“2006 Plan”), which became effective on May 24, 2007, the date the Company completed its initial public offering of common stock.

In May 2016, the Company adopted its 2016 Performance Incentive Plan (“2016 Plan”), which became effective on May 26, 2016, the date of approval of the 2016 Plan by the Company’s stockholders. The 2006 Plan became unavailable for new awards upon the effectiveness of the 2016 Plan. Unissued awards under the 2006 Plan are not available for future grant under the 2016 Plan. If any outstanding award under the 2006 Plan expires or is canceled, the shares allocable to the unexercised portion of that award will be added to the share reserve under the 2016 Plan and will be available for grant under the 2016 Plan.

In May 2020, the Company adopted its Amended and Restated 2016 Performance Incentive Plan (“Amended 2016 Plan”), which increased the aggregate number of shares of the Company’s common stock to be delivered pursuant to all awards granted under the 2016 Performance Incentive Plan by an additional 17,500,000 shares, and became effective on May 15, 2020, the date of approval of the Amended 2016 Plan by the Company’s stockholders. As of December 31, 2023, the Company had 6,250,580 shares available for future grant under the Amended 2016 Plan.

Service-Based Stock Options

The Company has granted service-based stock options to key employees that vest annually over the three years following the date of grant at a rate of 34%, 33% and 33%, respectively, if the holder is in service to the Company at each vesting date. The service-based stock options granted have contractual terms of 10 years, and exercise price for the options granted is equal to the closing market price of the Company's common stock on the date of grant. The stock options are subject to the terms and conditions of the 2006 and 2016 Plans and a Notice of Grant of Stock Option and Stock Option Agreement.

The following table summarizes the Company’s service-based stock option activities for the year ended December 31, 2023:


				Weighted
				Average
		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
	Number of	Exercise		Term	Value
	Shares	Price		(in years)	(in thousands)
Options outstanding as of December 31, 2022	10,116,340	$	6.00
Granted	3,030,439	$	4.78
Exercised	(98,592)	$	2.38
Forfeited or expired	(487,610)	$	7.29
Options outstanding as of December 31, 2023	12,560,577	$	5.68	6.71	$	5,369
Options exercisable as of December 31, 2023	8,117,695	$	5.54	5.63	$	5,345
Options vested and expected to vest as of December 31, 2023	12,560,577	$	5.68	6.71	$	5,369

As of December 31, 2023, there was $11.0 million of total unrecognized compensation cost related to unvested shares subject to outstanding service-based stock options. That cost is expected to be expensed over a remaining weighted average period of approximately 1.4 years. The total fair value of shares vested during the year ended December 31, 2023 was $11.3 million.

The fair value of each service-based stock option granted was estimated as of the date of grant using the Black-Scholes option pricing model and using the following assumptions:


	Year Ended December 31,
	2021	2022	2023
Dividend yield	0.0%	0.0%	0.0%
Expected volatility	76.8% to 96.8%	73.7% to 76.9%	75.2% to 76.6%
Risk-free interest rate	0.58% to 1.31%	1.52% to 4.34%	3.68% to 4.73%
Expected life in years	5.6 to 5.8	5.6 to 5.9	5.9 to 6.2

The volatility amounts used were estimated based on the historical volatility of the Company’s common stock over a term equal to the estimated life of the options. The expected lives used were based on historical exercise experience and the Company’s anticipated exercise periods for its outstanding stock options. The risk-free interest rates used were based on the U.S. Treasury yield curve with terms approximating the expected life of the stock options at the time of grant.

The weighted-average grant date fair value per share of service-based stock options granted during the years ended December 31, 2021, 2022 and 2023 were $5.90, $4.40, and $3.30, respectively. The aggregate intrinsic value of service-based options exercised during the years ended December 31, 2021, 2022 and 2023 were $10.1 million, $1.3 million, and $0.2 million, respectively. The Company recorded $9.9 million, $11.9 million, and $11.7 million of stock option expense relating to service-based stock options for the years ended December 31, 2021, 2022 and 2023, respectively. The Company has not recorded any tax benefit related to its service-based stock option expense.

Performance-Based Stock Options

The Company granted 1,640,000 performance-based stock options to certain executives and key employees in 2021. The options granted vest in multiple tranches in which the vesting of each tranche is contingent upon securing a defined RNG production volume following the date of grant, if the holder is in service to the Company upon the achievement of such performance hurdles. The performance-based stock options have contractual terms of 10 years, and the exercise price for the options granted is equal to the closing market price of the Company's common stock on the date of grant. The stock options are subject to the terms and conditions of the 2016 Plan and a Notice of Grant of Stock Option and Stock Option Agreement.

The following table summarizes the Company’s performance-based stock option activities for the year ended December 31, 2023:


				Weighted
				Average
		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
	Number of	Exercise		Term	Value
	Shares	Price		(in years)	(in thousands)
Options outstanding as of December 31, 2022	1,640,000	$	6.77
Granted	—	$	—
Exercised	—	$	—
Forfeited or expired	(25,000)	$	6.77
Options outstanding as of December 31, 2023	1,615,000	$	6.77	7.94	$	—
Options vested and exercisable as of December 31, 2023	403,750	$	6.77	7.94	$	—

As of December 31, 2023, there was $4.1 million of total unrecognized compensation cost related to unvested shares subject to outstanding performance-based stock options. Compensation cost for the performance-based stock options is recognized when attainment of the performance hurdles is determined to be probable and over a period in which the Company estimates the performance hurdles will be achieved. No shares subject to outstanding performance-based stock options vested in the year ended December 31, 2023; as such, the total fair value of shares vested during the year ended December 31, 2023 was $0.0 million.

The fair value of each performance-based stock option granted was estimated as of the date of grant using the Black-Scholes option pricing model and using the following assumptions:



		December 7, 2021
Dividend yield		0.0%
Expected volatility		77.1%
Risk-free interest rate		1.36%
Expected life in years		6.2

The volatility amount used was estimated based on (i) the historical volatility of the Company’s common stock over a term equal to the estimated life of the options and on (ii) implied volatility of the Company’s traded options. The expected life used was based on historical exercise experience and the Company’s anticipated exercise period for its outstanding performance-based stock options. The risk-free interest rate used was based on the U.S. Treasury yield curve with terms approximating the expected life of the stock options at the time of grant.

The weighted-average grant date fair value per share of performance-based stock options granted during the year ended December 31, 2021 was $4.58. No performance-based stock options were granted during the years ended December 31, 2022 and 2023. In addition, there were no performance-based stock options exercised during the years ended December

31, 2021, 2022 and 2023. The Company recognizes the grant date fair value of the options that are probable of being earned over the estimated performance period. Compensation cost relating to performance-based stock options was $1.0 million, $2.0 million, and $0.4 million for the years ended December 31, 2021, 2022 and 2023, respectively. The Company has not recorded any tax benefit related to its performance-based stock option expense.

Market-Based Stock Options

The Company granted 3,700,000 market-based stock options to select executives and employees in 2021. Market-based stock options vest if (i) the closing price of the Company’s common stock equals or exceeds $14.00 for twenty consecutive trading days, representing 207% of the closing market price of the Company’s common stock on the option grant date (the “Stock Price Condition”) and (ii) the holder is employed by the Company at the time the Stock Price Condition is satisfied. The market-based stock options have contractual terms of 10 years, and the exercise price for the options granted is equal to the closing market price of the Company's common stock on the date of grant. The stock options are subject to the terms and conditions of the 2016 Plan and a Notice of Grant of Stock Option and Stock Option Agreement.

The following table summarizes the Company’s market-based stock option activities for the year ended December 31, 2023:


				Weighted
				Average
		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
	Number of	Exercise		Term	Value
	Shares	Price		(in years)	(in thousands)
Options outstanding as of December 31, 2022	3,700,000	$	6.77
Granted	—	$	—
Exercised	—	$	—
Forfeited or expired	(50,000)	$	6.77
Options outstanding as of December 31, 2023	3,650,000	$	6.77	7.94	$	—
Options vested and exercisable as of December 31, 2023	—	$	—	—	$	—

As of December 31, 2023, there was no unrecognized compensation cost related to unvested shares subject to outstanding market-based stock options. That cost was fully expensed and recognized over the estimated derived service period of 2 years beginning on the date of grant. The Stock Price Condition was not met during the year ended December 31, 2023; as such, no vesting occurred.

The fair value of each market-based stock option granted was estimated on the date of grant using the Monte Carlo simulation model. The Monte Carlo simulation method is subject to variability as certain assumptions must be made, including the derived service period, which is estimated based on likely future stock price performance and volatility of the Company’s common stock price. The fair value of each market-based stock option granted was estimated using the following assumptions:



		December 7, 2021
Dividend yield		0.0%
Expected volatility		67.8%
Risk-free interest rate		1.5%
Expected life in years		10.0

The volatility amount used was based on the historical volatility of the Company’s common stock over a term equal to the estimated life of the options. The risk-free interest rate used was based on the U.S. Treasury yield curve with terms

approximating the expected life of the stock options at the time of grant. The expected life used was based on the Company’s anticipated exercise period for its outstanding market-based stock options as the simulation was run from the valuation date through the end of the contractual life of the options using weekly time steps.

The weighted-average grant date fair value per share of market-based stock options granted during the year ended December 31, 2021 was $4.87. No market-based stock options were granted during the years ended December 31, 2022 and 2023. In addition, there were no market-based stock options exercised during the years ended December 31, 2021, 2022 and 2023. The Company recorded $0.2 million, $9.4 million, and $8.2 million of compensation cost relating to market-based stock options during the years ended December 31, 2021, 2022 and 2023, respectively. The Company has not recorded any tax benefit related to its market-based stock option expense.

Service-Based Restricted Stock Units

The Company has granted service-based restricted stock units (“Service-Based RSUs”) to key employees that vest annually over the three years following the date of grant at a rate of 34%, 33% and 33%, respectively, if the holder is in service to the Company at each vesting date. The Service-Based RSUs are subject to the terms and conditions of the 2016 Plan and a Notice of Grant of Restricted Stock Unit and Restricted Stock Unit Agreement.

The following table summarizes the Company’s Service-Based RSU activities for the year ended December 31, 2023:


		Weighted
		Average
	Number of	Fair Value at
	Shares	Grant Date
RSU outstanding and unvested as of December 31, 2022	694,945	$	8.41
Granted	129,524	$	4.19
Vested	(418,274)	$	7.38
Forfeited or expired	(6,486)	$	10.08
RSU outstanding and unvested as of December 31, 2023	399,709	$	8.10

The weighted average grant-date fair value of RSUs granted during the years ended December 31, 2021, 2022 and 2023 was $10.24, $6.41 and $4.19, respectively.

As of December 31, 2023, there was $0.6 million of total unrecognized compensation cost related to unvested shares subject to outstanding Service-Based RSUs. That cost is expected to be expensed over a remaining weighted-average period of approximately 0.6 years.

The Company recorded $3.9 million, $3.1 million, and $3.0 million of expense during the years ended December 31, 2021, 2022 and 2023, respectively, related to the Service-Based RSUs. The Company has not recorded any tax benefit related to its Service-Based RSU expense.

Employee Stock Purchase Plan

On May 7, 2013, the Company adopted an employee stock purchase plan (the “2013 ESPP”), pursuant to which eligible employees may purchase shares of the Company’s common stock at 85% of the fair market value of the common stock on the last trading day of two consecutive, non-concurrent offering periods each year. The Company has reserved 2,500,000 shares of its common stock for issuance under the 2013 ESPP, and the first offering period under the ESPP commenced on September 1, 2013. At the Company’s annual meeting of stockholders held on May 19, 2022, the Company’s stockholders voted and approved the 2022 Employee Stock Purchase Plan (the “2022 ESPP”), making 2,500,000 shares of the Company's common stock available for issuance under the 2022 ESPP. Upon approval of the 2022 ESPP, the 2013 ESPP was terminated following the conclusion of the offering period dated June 30, 2022. The 2022 ESPP

does not have a “pour over” feature; as such, any unissued shares under the 2013 ESPP are no longer available for issuance under the 2022 ESPP.

The Company recorded $0.1 million, $0.1 million, and $0.1 million of expense for the years ended December 31, 2021, 2022 and 2023, respectively, related to the Company’s ESPPs. The Company has not recorded any tax benefit related to its ESPP expense. As of December 31, 2023, the Company had issued an aggregate of 102,666 shares pursuant to the 2022 ESPP.

Amazon Warrant

On April 16, 2021, the Company entered into a Project Addendum to Fuel Pricing Agreement (“Fuel Agreement”) with Amazon Logistics, Inc., a subsidiary of Amazon.com, Inc. (“Amazon”), and a Transaction Agreement with Amazon (the “Transaction Agreement”), pursuant to which, among other things, the Company issued to Amazon.com NV Investment Holdings LLC, a subsidiary of Amazon (“Amazon Holdings”), a warrant to purchase up to an aggregate of 53,141,755 shares (the “Warrant Shares”) of the Company’s common stock at an exercise price of $13.49 per share, which was a 21.3% premium to the $11.12 closing price of the common stock on April 15, 2021.

The Warrant Shares vest in multiple tranches, the first of which for 13,283,445 Warrant Shares vested upon execution of the Fuel Agreement. Subsequent tranches will vest over time based on fuel purchases by Amazon and its affiliates, up to a total of $500.0 million, excluding any payments attributable to “Pass Through Costs,” which consist of all costs associated with the delivered cost of gas and applicable taxes determined by reference to the selling price of gallons or gas sold.

Under the Transaction Agreement, the Company was required to use commercially reasonable efforts to obtain the approval of its stockholders with respect to the issuance of Warrant Shares in excess of 50,595,531 shares of common stock, pursuant to The Nasdaq Stock Market LLC’s Listing Rule 5635(b) (the “Stockholder Approval”). On June 14, 2021, the Company obtained Stockholder Approval.

As a result of the issuance of additional shares of common stock under the ATM Programs and in accordance with the terms of the warrant, on June 14, 2021, the number of shares of the Company’s common stock that may be purchased pursuant to the warrant, at an exercise price of $13.49 per share, increased by an aggregate of 5,625,959 shares (the “Additional Warrant Shares”). The Additional Warrant Shares vest in multiple tranches, the first of which for 1,406,490 Additional Warrant Shares vested on June 14, 2021. Subsequent tranches of the Additional Warrant Shares will vest over time based on fuel purchases by Amazon and its affiliates, consistent with the vesting schedule for the Warrant Shares as described above. The right to exercise the warrants and receive the Warrant Shares and Additional Warrant Shares (the “Amazon Warrant”) that have vested expires April 16, 2031.

Amazon Holdings may not exercise the Amazon Warrant to the extent such exercise would cause Amazon Holdings to beneficially own more than 4.999% of the number of shares of Common Stock outstanding immediately after giving effect to such exercise (excluding any unvested portion of the Amazon Warrant) (the “Beneficial Ownership Limitation”). Amazon Holdings may, however, waive or modify the Beneficial Ownership Limitation by providing written notice to the Company sixty-one (61) days before such waiver or modification becomes effective (or immediately upon written notice to the Company to the extent the Company is subject to certain acquisition transactions pursuant to a tender or exchange offer).

Non-cash stock-based sales incentive contra-revenue charges (“Amazon Warrant Charges”) associated with the Amazon Warrant are recognized as the customer purchases fuel and vesting conditions become probable of being achieved based on the grant date fair value of the Amazon Warrant. The fair values of the Amazon Warrant were determined as of the grant date in accordance with ASC 718, Compensation – Stock Compensation, using the Black-Scholes option pricing model and the following assumptions:


	April 16, 2021	June 14, 2021
Dividend yield	0.0%	0.0%
Expected volatility	66.46%	67.97%
Risk-free interest rate	1.59%	1.49%
Expected term in years	10.0	9.8

The volatility amounts used were estimated based on the historical volatility of the Company’s common stock over a period matching the assumed term of the Amazon Warrant. The expected terms used were based on the term of the Amazon Warrant at the date of issuance. The risk-free interest rates used were based on the U.S. Treasury yield curve for the expected term of the Amazon Warrant at the date of issuance.

The following table summarizes the Amazon Warrant activities for the year ended December 31, 2023:


		Warrant
		Shares
Outstanding and unvested as of December 31, 2022		42,314,667
Granted		—
Vested		(4,701,632)
Outstanding and unvested as of December 31, 2023		37,613,035

As a result of the immediate vesting of a portion of the Warrant Shares and Additional Warrant Shares, the Company recognized Amazon Warrant Charges, in the second quarter of 2021, of $76.6 million and a customer incentive asset of $38.4 million representing Amazon Warrant Charges associated with future contractually required minimum fuel purchases which will be recognized as the fuel is purchased.

During the years ended December 31, 2021, 2022 and 2023, Amazon Warrant Charges in the consolidated statements of operations were $83.6 million, $24.3 million and $60.6 million, respectively. Amazon Warrant Charges for the year ended December 31, 2021 included $76.6 million from the immediate vesting of a portion of the Warrant Shares and Additional Warrant Shares and $7.0 million associated with fuel purchases. Amazon Warrant Charges for the years ended December 31, 2022 and 2023 were related to customer fuel purchases. As of December 31, 2022, the Company had a customer incentive asset of $22.2 million, classified in “Prepaid expenses and other current assets” in the accompanying consolidated balance sheets. As of December 31, 2023, the customer incentive asset had been fully amortized.

Stonepeak Warrant

In connection with the Stonepeak Credit Agreement and the related Loan Facility (see Note 12), on December 12, 2023, the Company issued warrants (the “Stonepeak Warrant”) to Stonepeak, pursuant to a warrant agreement, dated December 12, 2023 (the “Warrant Agreement”), allowing Stonepeak to purchase 10,000,000 shares of the Company’s common stock at an exercise price of $5.50 and an additional 10,000,000 shares of the Company’s common stock at an exercise price of $6.50.

The Stonepeak Warrant vested upon the execution of the Warrant Agreement and is exercisable at any time after December 12, 2025. The Stonepeak Warrant has an 8.5 year term, and the right to exercise the warrants expires on June 15, 2032. The Stonepeak Warrant contains a “cashless exercise” feature that allows the holder(s) to exercise the warrants without a cash payment to the Company upon the terms set forth in the Warrant Agreement. The number of shares of the

Company’s common stock for which the Stonepeak Warrant is exercisable and the associated exercise price are subject to certain customary anti-dilution and continuity adjustments as set forth in the Warrant Agreement.

Stonepeak may not exercise the Stonepeak Warrant to the extent such exercise would cause Stonepeak to beneficially own more than 9.999% of the number of shares of the Company’s common stock outstanding immediately after giving effect to such exercise (the “Stonepeak Beneficial Ownership Limitation”). Stonepeak may, however, waive or amend the Stonepeak Beneficial Ownership Limitation by providing written notice to the Company sixty-one (61) days before such waiver or amendment becomes effective (or immediately upon written notice to the Company to the extent the Company is subject to certain acquisition transactions pursuant to a tender or exchange offer).

The Stonepeak Warrant, issued in conjunction with the funding of the Senior Term Loan, was determined to be a separate unit of account from the Loan Facility based on evaluation of the contractual terms of the Stonepeak Credit Agreement and the Warrant Agreement. As a result, amounts were allocated to the Stonepeak Warrant using the relative fair value method. The Stonepeak Warrant is deemed an equity classified instrument because the underlying warrants (1) do not embody an obligation of the Company, (2) are deemed to be indexed to the Company’s own common stock, and (3) meet all the conditions for equity classification. As such, the Stonepeak Warrant is measured at fair value as of the issuance date, and subsequent changes in fair value will not be recognized in earnings. The fair values of the Stonepeak Warrant as of the issuance date were determined using the Black-Scholes option pricing model and the following assumptions:


	December 12, 2023	December 12, 2023
Exercise price	5.50	6.50
Dividend yield	0.0%	0.0%
Expected volatility	72.96%	72.96%
Risk-free interest rate	4.22%	4.22%
Expected term in years	8.5	8.5

The volatility amounts used were estimated based on the historical volatility of the Company’s common stock over a period matching the assumed term of the Stonepeak Warrant. The expected terms used were based on the term of the Stonepeak Warrant on the date of issuance. The risk-free interest rates used were based on the U.S. Treasury yield curve for the expected term of the Stonepeak Warrant on the date of issuance.

As a result of the issuance and vesting of the Stonepeak Warrant, the Company recognized $42.4 million, representing the fair value of the Stonepeak Warrant, in “Additional paid-in capital” included in “Stockholders’ equity” and recorded $31.8 million, classified as debt discount to the gross principal of the Senior Term Loan, and $10.6 million, classified as a warrant asset included in “Notes receivable and other long-term assets, net” in the consolidated balance sheets as of December 31, 2023. The debt discount relating to the Stonepeak Warrant will be amortized using the interest method in accordance with ASC 835-30, Imputation of Interest, over the contractual term of the Loan Facility and will be recognized in earnings as interest expense in the consolidated statements of operations. The warrant asset represents value the Company obtained from the issuance of the Stonepeak Warrant in exchange for the $100.0 million delayed draw term loan commitment (see Note 12). The warrant asset will be proportionately reclassified to debt discount when amounts are drawn from the delayed draw term loan commitment, reducing the initial net carrying amount of the funded debt. These amounts recognized in connection with the Stonepeak Warrant were excluded from the accompanying consolidated statements of cash flows as they were non-cash financing activities.

The following table summarizes the Stonepeak Warrant activities for the year ended December 31, 2023:


		Warrant
		Shares
Outstanding and unexercised as of December 31, 2022		—
Granted		20,000,000
Exercised		—
Outstanding and unexercised as of December 31, 2023		20,000,000

Stockholders' Equity - Share Repurchase program (Details) - USD ($) $ in Thousands	12 Months Ended			34 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 07, 2021	Mar. 12, 2020
Stockholders' Equity Note [Abstract]
Approved share repurchase program					$ 50,000	$ 30,000
Repurchase of common stock (in shares)	0
Cost to repurchase common stock	$ 175	$ 6,122	$ 2,916
Amount utilized under the repurchase plan				$ 23,500
Stock Repurchase Program Total Stock Repurchased				9,387,340

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References + Details

- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References + Details

Short-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 158,158	$ 139,915
Gross Unrealized Gain (Loss)	28
Gross Unrealized Gain (Loss)		(346)
Estimated Fair Value	158,186	139,569
Zero coupon bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		74,524
Gross Unrealized Gain (Loss)		(365)
Estimated Fair Value		74,159
U.S. government securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	157,628	64,861
Gross Unrealized Gain (Loss)	28	19
Estimated Fair Value	157,656	64,880
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	530	530
Gross Unrealized Gain (Loss)		0
Estimated Fair Value	$ 530	$ 530

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (a)
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Section 50
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-Subparagraph (c)
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 3
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Fair Value Measurements - Transfers (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Asset transferred level 3 net	$ 0	$ 0
Liabilities transferred level 3 net	$ 0	$ 0

Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2023

Payables and Accruals [Abstract]

Schedule of accrued liabilities

Accrued liabilities as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Accrued alternative fuels incentives ⁽¹⁾	$	34,239	$	41,609
Accrued employee benefits		5,128		5,315
Accrued gas and equipment purchases		22,008		17,485
Accrued interest		1,827		1,451
Accrued property and other taxes		3,782		4,502
Accrued salaries and wages		6,857		8,697
Other ⁽²⁾		16,238		12,475
Total accrued liabilities	$	90,079	$	91,534

(1)	Includes amount for RINs, LCFS Credits, and AFTC payable to third parties.

(2)	No individual item in “Other” exceeds 5% of total current liabilities.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Significant Accounting Policies

Note 1 —Summary of Significant Accounting Policies

The Company and Nature of Business

Clean Energy Fuels Corp., together with its majority and wholly owned subsidiaries (hereinafter collectively referred to as the “Company,” unless the context or the use of the term indicates or requires otherwise) is engaged in the business of selling renewable and conventional natural gas as alternative fuels for vehicle fleets and related fueling solutions to its customers, primarily in the United States (“U.S.”) and Canada. The Company’s principal business is supplying renewable natural gas (“RNG”) and conventional natural gas, in the form of compressed natural gas (“CNG”) and liquefied natural gas (“LNG”), for medium and heavy-duty vehicles and providing operation and maintenance (“O&M”) services to public and private vehicle fleet customer stations. The Company is also focused on developing, owning, and operating dairy and other livestock waste RNG projects and supplying RNG (procured from third party sources and from the DR JV, one of the Company’s jointly owned RNG production facilities (see Note 4)) to its customers in the heavy and medium-duty commercial transportation sector.

As a comprehensive clean energy solutions provider, the Company also designs and builds, as well as operates and maintains, public and private vehicle fueling stations in the United States and Canada; sells and services compressors and other equipment used in RNG production and at fueling stations; transports and sells RNG and conventional natural gas, in the form of CNG and LNG, via “virtual” natural gas pipelines and interconnects; sells U.S. federal, state and local government credits it generates by selling RNG in the form of CNG and LNG as a vehicle fuel, including Renewable Identification Numbers (“RIN Credits” or “RINs”) under the federal Renewable Fuel Standard Phase 2 and credits under the California, Oregon, and Washington Low Carbon Fuel Standards (collectively, “LCFS Credits”); and obtains federal, state and local tax credits, grants and incentives.

Basis of Presentation

The accompanying consolidated financial statements include the accounts of the Company and its subsidiaries, and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to state fairly the Company’s consolidated financial position, results of operations, comprehensive income (loss), stockholders’ equity, and cash flows in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). All intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the accompanying consolidated financial statements and these notes. Actual results could differ from those estimates and may result in material effects on the Company’s operating results and financial position. Significant estimates made in preparing the accompanying consolidated financial statements include (but are not limited to) those related to revenue recognition, fair value measurements, goodwill and long-lived asset valuations and impairment assessments, income tax valuations, stock-based compensation expense and stock-based sales incentive charges.

Inventory

Inventory consists of raw materials and spare parts, work in process and finished goods and is stated at the lower of cost (first-in, first-out) or net realizable value. The Company evaluates inventory balances for excess quantities and obsolescence by analyzing estimated demand, inventory on hand, sales levels and other information and reduces inventory balances to net realizable value for excess and obsolete inventory based on this analysis.

Inventories consisted of the following as of December 31, 2022 and 2023 (in thousands):


	2022		2023
Raw materials and spare parts	$	37,144	$	45,335
Total inventory	$	37,144	$	45,335

Derivative Instruments and Hedging Activities

In connection with the Company’s Zero Now truck financing program, the Company entered into commodity swap contracts in October 2018 intended to manage risks related to the diesel-to-natural gas price spread in connection with the natural gas fuel supply commitments the Company makes in its fueling agreements with fleet operators that participate in the Zero Now program. The Company has not designated any derivative instruments as hedges for accounting purposes and does not enter into such instruments for speculative trading purposes. These derivative instruments are recorded in the accompanying consolidated balance sheets and are measured as either an asset or liability at fair value with changes in fair value recognized in earnings. See Note 7 for more information.

Property and Equipment

Property and equipment are recorded at cost. Depreciation and amortization are recognized over the estimated useful lives of the assets using the straight-line method. The estimated useful lives of depreciable assets are three to twenty years for LNG liquefaction plant assets, up to ten years for station equipment and LNG trailers, and three to seven years for all other depreciable assets. Leasehold improvements are amortized over the shorter of their estimated useful lives or related lease terms. Periodically, the Company receives cash grant funding to assist in the financing of fueling station construction. The Company initially records the grant proceeds as a reduction of the cost of the respective asset and subsequently amortizes the grant proceeds over the estimated useful life of the asset, resulting in lower total depreciation expense recognized over the estimated useful life of the asset.

Grant proceeds received for the years ended December 31, 2021 and 2023 were approximately $0.5 million and $1.9 million, respectively. No grant proceeds were received for the year ended December 31, 2022. Gross grant proceeds of $24.9 million and $25.9 million were included in “Land, property and equipment, net” in the accompanying consolidated balance sheets as of December 31, 2022 and 2023, respectively. Related accumulated amortization of the grant proceeds was $16.5 million and $17.0 million as of December 31, 2022 and 2023, respectively. The Company recorded amortization expense relating to grant proceeds of $1.7 million, $1.4 million and $1.5 million for the years ended December 31, 2021, 2022 and 2023, respectively.

Leases

On January 1, 2019, the Company adopted Accounting Standards Codification (“ASC”) 842, Leases, whereby leases are classified as either operating leases or finance leases.

At the inception of a contract the Company assesses whether the contract is, or contains, a lease. The Company’s assessment is based on: (1) whether the contract involves the use of a distinct identified asset, (2) whether the Company obtains the right to substantially all the economic benefit from the use of the asset throughout the period, and (3) whether the Company has the right to direct the use of the asset. The commencement date of the contract is the date the lessor makes the underlying asset available for use by the lessee.

Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset during the lease term and lease liabilities represent obligations to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the commencement date based on the net present value of fixed lease payments over the lease term. ROU assets also include any initial direct costs and advance lease payments made and exclude lease incentives. Lease liabilities also include terminal purchase options when deemed reasonably certain to exercise. The Company’s lease term includes

options to extend when it is reasonably certain that it will exercise that option. The Company has elected not to recognize ROU assets and lease liabilities for short-term leases that have a term of 12 months or less; the Company recognizes lease expense for these leases on a straight-line basis over the lease term.

As most of the Company’s operating leases do not have an implicit rate that can be readily determined, the Company uses its secured incremental borrowing rate for the same term as the underlying lease based on information available at lease commencement. For finance leases, the Company uses the rate implicit in the lease.

The lease classification affects the expense recognition on the consolidated statements of operations. Operating lease charges are recorded in “Cost of sales, exclusive of depreciation and amortization,” and “Selling, general and administrative” expense. Finance lease charges are split, whereby depreciation on assets under finance leases is recorded in “Depreciation and amortization” expense and an implied interest component is recorded in “Interest expense.” The expense recognition for operating leases and finance leases is substantially consistent with legacy accounting.

Long-Lived Assets

The Company reviews the carrying value of its long-lived assets, including property and equipment and intangible assets with finite useful lives, for impairment whenever events or changes in circumstances indicate that the carrying value of an asset or asset group may not be recoverable. Events that could result in an impairment review include, among others, a significant decrease in the operating performance of a long-lived asset or asset group or the decision to close a fueling station. Impairment testing involves a comparison of the sum of the undiscounted future cash flows of the asset or asset group to its carrying amount. If the sum of the undiscounted future cash flows exceeds the carrying amount, then no impairment exists. If the carrying amount exceeds the sum of the undiscounted future cash flows, then a second step is performed to determine the amount of impairment, if any, to be recognized. An impairment loss is recognized to the extent that the carrying amount of the asset or asset group exceeds its fair value. The fair value of the asset or asset group is based on estimated discounted future cash flows of the asset or asset group using a discount rate commensurate with the related risk. The estimate of future cash flows requires management to make assumptions and to apply judgment, including forecasting future sales and expenses and estimating useful lives of the assets. These estimates can be affected by a number of factors, including, among others, future results, demand, and economic conditions, many of which can be difficult to predict.

There were no impairments of the Company’s long-lived assets in the years ended December 31, 2021, 2022 and 2023.

Intangible assets with finite useful lives are amortized over their respective estimated useful lives using the straight-line method. The estimated useful lives of intangible assets with finite useful lives are one to eight years for customer relationships, one to fifty years for acquired contracts, two to ten years for trademarks and trade names, and three years for non-compete agreements.

The Company’s intangible assets as of December 31, 2022 and 2023 were as follows (in thousands):


	2022		2023
Customer relationships	$	5,376	$	5,376
Acquired contracts		10,299		10,749
Trademark and trade names		2,700		2,700
Non-compete agreements		860		860
Total intangible assets		19,235		19,685
Less accumulated amortization		(13,320)		(13,320)
Net intangible assets	$	5,915	$	6,365

Amortization expense of intangible assets was $0.5 million for the year ended December 31, 2021. No amortization expense relating to intangible assets was recognized for the years ended December 31, 2022 and 2023.

In connection with the Company’s investment in anaerobic digester gas (“ADG”) RNG production projects, the Company acquired contractual rights relating to manure feedstock totaling $0.4 million and $0.5 million in 2022 and 2023, respectively. The amounts paid for contractual rights to manure feedstock are classified and included under “Acquired contracts” in the table above. The acquired contractual rights to manure feedstock have a contractual term ranging from 20 to 50 years and will be amortized over the contractual term using the straight-line method of amortization, commencing on the date of commercial operation of the ADG RNG facility.

Estimated amortization expense subsequent to the year ended December 31, 2023 is expected to be approximately $0.0 million in 2024, $0.2 million in 2025, $0.3 million in 2026, $0.3 million in 2027, $0.3 million in 2028, and $5.3 million thereafter.

Goodwill

Goodwill represents the excess of costs incurred over the fair value of the net assets of acquired businesses. The Company assesses its goodwill using either a qualitative or quantitative approach to determine whether it is more likely than not that the fair value of its reporting unit is less than its carrying value. The Company is required to use judgment when applying the goodwill impairment test, including, among other considerations, the identification of reporting unit(s), the assessment of qualitative factors, and the estimation of fair value of a reporting unit in the quantitative approach. The Company determined that it is a single reporting unit for the purpose of goodwill impairment tests. The Company performs the impairment test annually on October 1, or more frequently if facts and circumstances warrant a review.

The qualitative goodwill assessment includes the evaluation of potential impact on a reporting unit’s fair value of certain events and circumstances, including its enterprise value, macroeconomic conditions, industry and market considerations, cost factors, and other relevant entity-specific events. If it is determined, based upon the qualitative assessment, that it is more likely than not that the reporting unit’s fair value is less than its carrying amount, then a quantitative impairment test is performed.

The quantitative assessment estimates the reporting unit’s fair value based on its enterprise value plus an assumed control premium as evidence of fair value. The estimates used to determine the fair value of the reporting unit may change based on results of operations, macroeconomic conditions, stock price fluctuations, or other factors. Changes in these estimates could materially affect our assessment of the fair value and goodwill impairment for the reporting unit.

During the years ended December 31, 2021, 2022 and 2023, the Company utilized the quantitative approach and concluded that there were no impairments to goodwill.

The following table summarizes the activity related to the carrying amount of goodwill (in thousands):


Balance as of December 31, 2021	$	64,328
Balance as of December 31, 2022	$	64,328
Balance as of December 31, 2023	$	64,328

Revenue Recognition

The Company recognizes revenue when control of the promised goods or services is transferred to its customers, in an amount that reflects the consideration to which it expects to be entitled in exchange for the goods or services. To achieve that core principle, a five-step approach is applied: (1) identify the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue allocated to each performance obligation when the Company satisfies

the performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account for revenue recognition.

The Company is generally the principal in its customer contracts because it has control over the goods and services prior to them being transferred to the customer, and as such, revenue is recognized on a gross basis. Sales and usage-based taxes are excluded from revenues. Revenue is recognized net of allowances for returns and any taxes collected from customers, which are subsequently remitted to governmental authorities.

Product Revenue

Volume-Related

The Company’s volume-related product revenue consists of sales of RNG and conventional natural gas, in the form of CNG and LNG, AFTC (defined below) incentives, and sales of RINs and LCFS Credits in addition to Amazon Warrant Charges (defined in Note 13) and changes in fair value of the Company’s derivative instruments associated with providing fuel to customers under contracts.

RNG and conventional natural gas are sold pursuant to contractual commitments over defined delivery periods. These contracts typically include a stand-ready obligation to supply natural gas. The Company applies the ‘right to invoice’ practical expedient and recognizes fuel revenue in the amount to which the Company has the right to invoice. The Company has a right to consideration based on the amount of gasoline gallon equivalents (“GGEs”) of fuel dispensed by the customer and current pricing conditions. The Company calculates one GGE to equal 125,000 British Thermal Units (“BTUs”), and, as such, one million BTUs (“MMBTU”) equal eight GGEs. Customers are typically billed on a monthly basis. Since payment terms are less than a year, the Company has elected the practical expedient which allows it to not assess whether a customer contract has a significant financing component.

Contract modifications are not distinct from the existing contract and are typically renewals of fuel sales. As a result, these modifications are accounted for as if they were part of the existing contract. The effect of a contract modification on the transaction price is recognized prospectively.

The Company sells RINs and LCFS Credits to third parties that need the credits to comply with federal and state requirements. Revenue is recognized on these credits when there is an agreement in place to monetize the credits at a determinable price and the RNG fuel has been sold. The sales price for some environmental credit transactions may not be determinable in the period in which the RNG was sold as pricing is established in the quarter after the RNG was sold. In these circumstances, revenue from RIN and LCFS credits is recognized once the sales price has been established and therefore is considered determinable.

Amazon Warrant Charges are determined based on the grant date fair value of the award, and the associated non-cash stock-based sales incentive charges, which are recorded as a reduction of revenue, are recognized as the customer purchases fuel and vesting conditions become probable of being achieved. See discussion under “Amazon Warrant” below and Note 13 for additional information.

The changes in fair value of derivative instruments relate to the Company’s commodity swap and customer fueling contracts under the Zero Now truck financing program. The contracts are measured at fair value with changes in fair value recorded in the accompanying consolidated statements of operations in the period incurred. The amounts are classified as revenue because the Company’s commodity swap contracts are used to economically offset the risk associated with the diesel-to-natural gas price spread resulting from existing and anticipated customer fueling contracts under the Company’s Zero Now truck financing program. See Note 7 for more information about these derivative instruments. For the years ended December 31, 2021, 2022 and 2023, changes in the fair value of commodity swaps and customer contracts amounted to a gain (loss) of $(3.5) million, $0.5 million, and ($0.2) million, respectively.

AFTC is generated when RNG or conventional natural gas is sold for use as fuel to operate a motor vehicle. See discussion under “Alternative Fuel Excise Tax Credit” below for more information about AFTC, which is not recognized as revenue until the period the credit is authorized through federal legislation.

Station Construction Sales

Station construction contracts are generally short-term, except for certain larger and more complex stations, which can take up to 24 months to complete. For most of the Company’s station construction contracts, the customer contracts with the Company to provide a significant service of integrating a complex set of tasks and components into a single station. Hence, the entire contract is accounted for as one performance obligation.

The Company recognizes revenue over time as the Company performs under its station construction contracts because of the continual transfer of control of the goods to the customer, who typically controls the work in process. Revenue is recognized based on the extent of progress towards completion of the performance obligation and is recorded proportionally as costs are incurred. Costs to fulfill the Company’s obligations under these contracts typically include labor, materials and subcontractors’ costs, other direct costs and an allocation of indirect costs.

Refinements of estimates to account for changing conditions and new developments are continuous and characteristic of the process. Many factors that can affect contract profitability may change during the performance period of the contract, including differing site conditions, the availability of skilled contract labor, the performance of major suppliers and subcontractors, and unexpected changes in material costs. Because a significant change in one or more of these estimates could affect the profitability of these contracts, the contract price and cost estimates are reviewed periodically as work progresses and adjustments proportionate to the cost-to-cost measure of progress are reflected in contract revenues in the reporting period when such estimates are revised. Provisions for estimated losses on uncompleted contracts are recorded in the period in which the losses become known.

Contract modifications are typically expansions in scope of an existing station construction project. As a result, these modifications are accounted for as if they were part of the existing contract. The effect of a contract modification on the transaction price and the Company’s measure of progress for the performance obligation to which it relates is recognized as an adjustment to revenue (either as an increase or a reduction) on a cumulative catch-up basis.

Under the typical payment terms of the Company’s station construction contracts, the customer makes either performance-based payments (“PBPs”) or progress payments. PBPs are interim payments of the contract price based on quantifiable measures of performance or the achievement of specified events or milestones. Progress payments are interim payments of costs incurred as the work progresses. For some of these contracts, the Company may be entitled to receive an advance payment. The advance payment typically is not considered a significant financing component because it is used to meet working capital demands that can be higher in the early stages of a construction contract and to protect the Company if the customer fails to adequately complete some or all of its obligations under the contract. In addition, the customer retains a small portion of the contract price until completion of the contract. Such retained portion of the contract price is not considered a significant financing component because the intent is to protect the customer.

In certain contracts with its customers, the Company agrees to provide multiple goods or services, including construction of and sale of a station, O&M services, and sale of fuel to the customer. These contracts have multiple performance obligations because the promise to transfer each separate good or service is separately identifiable and distinct. This evaluation requires significant judgment and the decision to combine a group of contracts or separate the combined or single contract into multiple performance obligations could change the amount of revenue recognized in one or more periods.

The Company allocates the contract price to each performance obligation using best estimates of the standalone selling price of each distinct good or service in the contract. The primary method used to estimate the standalone selling price for fuel and O&M services is observable standalone sales, and the primary method used to estimate the standalone selling

price for station construction sales is the expected cost plus a margin approach because the Company sells customized customer-specific solutions. Under this approach, the Company forecasts expected costs of satisfying a performance obligation and then adds an appropriate margin for the good or service.

Service Revenue

O&M Services

O&M and other services are sold pursuant to contractual commitments over defined performance periods. These contracts typically include a stand-ready obligation to provide O&M and/or other services based on a committed and agreed upon routine maintenance schedule or when and if called upon by the customer.

The Company applies the ‘right to invoice’ practical expedient and recognizes O&M and other services revenue in the amount to which the Company has the right to invoice. The Company has a right to consideration based on services rendered or on amount of GGEs of fuel dispensed by the customer multiplied by an agreed-upon rate. Customers are typically billed on a monthly basis. Since payment terms are less than a year, the Company has elected the practical expedient which allows it to not assess whether a customer contract has a significant financing component.

Contract modifications are not distinct from the existing contract and are typically renewals of O&M and other service sales. As a result, these modifications are accounted for as if they were part of the existing contract. The effect of a contract modification on the transaction price is recognized prospectively.

Other services

The majority of other services revenue consist of sales of used natural gas heavy-duty trucks purchased by the Company and management fees relating to management services provided to the Company’s equity method investees and joint ventures with TotalEnergies and bp. Revenue on sales contracts of used natural gas trucks is recognized at the point in time when the customer accepts delivery of the truck. Management fee revenue is recognized over time on a monthly basis as services are rendered by the Company.

Alternative Fuel Excise Tax Credit

Under separate pieces of U.S. federal legislation, the Company was eligible to receive a federal alternative fuel excise tax credit (“AFTC”) for its natural gas vehicle fuel sales made between October 1, 2006 and December 31, 2021. The AFTC credit was equal to $0.50 per GGE of CNG that the Company sold as vehicle fuel, and $0.50 per diesel gallon of LNG that the Company sold as vehicle fuel in 2020 and 2021. The Inflation Reduction Act of 2022, enacted on August 16, 2022 (the “IRA”), extended AFTC for an additional three years, beginning retroactively to January 1, 2022. AFTC incentive under the extension period remains at $0.50 per GGE of CNG and $0.50 per diesel gallon of LNG that the Company sells as vehicle fuel through December 31, 2024.

Based on the service relationship with its customers, either the Company or its customer claims the credit. The Company records its AFTC credits, if any, as revenue in its consolidated statements of operations because the credits are fully payable to the Company and do not offset income tax liabilities. As such, the credits are not deemed income tax credits under the accounting guidance applicable to income taxes.

LNG Transportation Costs

The Company records the costs incurred to transport LNG to its customers in “Product cost of sales” in the accompanying consolidated statements of operations.

Advertising Costs

Advertising costs are expensed as incurred. Advertising costs were immaterial for the years ended December 31, 2021, 2022 and 2023.

Stock-Based Compensation

The Company recognizes compensation expense for all stock‑based payment arrangements over the requisite service period of the award and recognizes forfeitures as they occur. For service and performance-based stock options, the Company determines the grant date fair value using the Black‑Scholes option pricing model, which requires the input of certain assumptions, including the expected life of the stock‑based payment award, stock price volatility and risk‑free interest rate. For market-based stock options, the Company determines the grant date fair value using the Monte Carlo simulation model, which requires the input of certain assumptions, including the derived service period and the volatility of the Company’s stock price. For restricted stock units, the Company determines the grant date fair value based on the closing market price of its common stock on the date of grant.

Amazon Warrant

The Amazon Warrant (as defined in Note 13) is accounted for as an equity instrument and measured in accordance with ASC 718, Compensation – Stock Compensation. To determine the fair value of the Amazon Warrant, the Company used the Black-Scholes option pricing model, which is based in part on assumptions that require management to use judgment. For awards granted to a customer, which are not in exchange for distinct goods or services, the fair value of the awards earned based on service or performance conditions is recorded as a reduction of the transaction price in accordance with ASC 606, Revenue from Contracts with Customers. Based on the fair value of the award, the Company determines the amount of non-cash stock-based sales incentive charges on the customer’s pro-rata achievement of vesting conditions, which is recorded as a reduction of revenue in the consolidated statements of operations.

Stonepeak Warrant

The Stonepeak Warrant (as defined in Note 13), issued in conjunction with the funding of the Senior Term Loan, is deemed as a separate unit of account from the Loan Facility based on evaluation of the contractual terms of the Stonepeak Credit Agreement and the Warrant Agreement. As a result, amounts are allocated to the Stonepeak Warrant using the relative fair value method and are accounted for as paid-in capital. The Stonepeak Warrant is classified as an equity instrument because the underlying warrants (1) do not embody an obligation of the Company, (2) are deemed to be indexed to the Company’s own common stock, and (3) meet all the conditions for equity classification. As a result, the Stonepeak Warrant is measured at fair value as of the issuance date, and subsequent changes in fair value will not be recognized in earnings. The fair values of the Stonepeak Warrant as of the issuance date were determined using the Black-Scholes option pricing model. In addition, upon the recognition of the Stonepeak Warrant, the Company recognized a warrant asset and additional debt discount to the gross principal of the Senior Term Loan. The additional debt discount relating to the Stonepeak Warrant will be amortized using the interest method in accordance with ASC 835-30, Imputation of Interest, over the contractual term of the Loan Facility and will be recognized in earnings as interest expense in the consolidated statements of operations. The warrant asset will be proportionately reclassified to debt discount when amounts are drawn from the delayed draw term loan commitment, reducing the initial net carrying amount of the funded debt.

Tourmaline Joint Development

In April 2023, the Company and Tourmaline Oil Corp. (“Tourmaline”) announced a CAD $70 million Joint Development Agreement to build and operate a network of CNG stations along key highway corridors across Western Canada. Under a 50-50 shared investment, the Company and Tourmaline expect to construct and commission up to 20 CNG fueling stations over the next five years, allowing heavy-duty trucks and other commercial transportation fleets that operate in the area to transition to the use of CNG, a lower carbon alternative to gasoline and diesel. Costs associated with

station construction and profit and loss arising from station operation are shared 50-50 between the Company and Tourmaline. This arrangement between the Company and Tourmaline to jointly develop, build and operate CNG fueling stations is accounted for in accordance with ASC 808, Collaborative Arrangements, which states that (1) costs incurred and revenue generated from transactions with third parties be separately recorded by each participant in its own financial statements, (2) the participant who is deemed to be the principal for a given transaction under ASC 606, Revenue from Contracts with Customers, will record the transaction on a gross basis in its financial statements, and (3) payments between participants that are within the scope of other authoritative accounting literature on income statement classification shall be accounted for using the relevant provisions of that literature. If the payments are not within the scope of other authoritative accounting literature, then the income statement classification for the payments shall be based on an analogy to authoritative accounting literature or if there is no appropriate analogy, a reasonable, rational, and consistently applied accounting policy election.

In accordance with ASC 606, the Company determined that it is the principal for the revenue generated from third parties under this collaborative arrangement with Tourmaline; as such, the associated revenue and cost of sales generated and incurred are recognized on a gross basis in the consolidated statements of operations. Net participation of profit and loss owed to or from Tourmaline is recorded as an increase or decrease to cost of sales, respectively, because the transaction is not deemed to be with a customer within the scope of ASC 606. Capitalized station costs are presented at half of the total development and construction costs in the consolidated balance sheets, corresponding to the Company’s 50% ownership in the shared assets.

Income Taxes

Income taxes are computed using the asset and liability method. Under this method, deferred income taxes are recognized by applying enacted statutory tax rates applicable to future years to differences between the tax bases and financial carrying amounts of existing assets and liabilities. The impact on deferred taxes of changes in tax rates and laws, if any, is applied to the years during which temporary differences are expected to be settled and are reflected in the consolidated financial statements in the period of enactment. Valuation allowances are established when management determines it is more likely than not that deferred tax assets will not be realized. When evaluating the need for a valuation analysis, we use estimates involving a high degree of judgment including projected future U.S. GAAP income and the amounts and estimated timing of the reversal of any deferred tax assets and liabilities.

The Company has a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not sustainable upon examination by taxing authorities based on the technical merits of the position. The amount recognized is measured as the largest amount of benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement. The Company recognizes potential accrued interest and penalties related to unrecognized tax benefit in income tax expense.

The Company operates within multiple domestic and foreign taxing jurisdictions and is subject to audit in these jurisdictions. These audits can involve complex issues, which may require an extended period of time to resolve. Although the Company believes that adequate consideration has been given to these issues, it is possible that the ultimate resolution of these issues could be significantly different from originally estimated.

Net Loss Per Share

Basic net loss per share is computed by dividing the net loss attributable to Clean Energy Fuels Corp. by the weighted-average number of common shares outstanding and common shares issuable for little or no cash consideration during the period. Diluted net loss per share is computed by dividing the net loss attributable to Clean Energy Fuels Corp. by the weighted-average number of common shares outstanding and common shares issuable for little or no cash consideration during the period and potentially dilutive securities outstanding during the period, and therefore reflects the dilution from common shares that may be issued upon exercise or conversion of these potentially dilutive securities, such as stock

options, warrants, convertible notes and restricted stock units. The dilutive effect of stock awards and warrants is computed under the treasury stock method. The dilutive effect of convertible notes and restricted stock units is computed under the if-converted method. Potentially dilutive securities are excluded from the computations of diluted net loss per share if their effect would be antidilutive.

Foreign Currency Translation and Transactions

The Company uses the local currency as the functional currency of its foreign subsidiary and equity method investment. Accordingly, all assets and liabilities outside the U.S. are translated into U.S. dollars at the rate of exchange in effect at the balance sheet date. Revenue and expense items are translated at the weighted-average exchange rates prevailing during the period. Foreign currency translation adjustments are recorded in “Accumulated other comprehensive loss” in stockholders’ equity.

Foreign currency transactions occur when there is a transaction denominated in other than the respective entity’s functional currency. The Company records the changes in the exchange rate for these transactions in its consolidated statements of operations. For each of the years ended December 31, 2021, 2022 and 2023, foreign exchange transaction gains and (losses) were immaterial and were included in “Other income, net” in the accompanying consolidated statements of operations.

Comprehensive Loss

Comprehensive loss is defined as the change in equity (net assets) of a business enterprise during the period from transactions and other events and circumstances from non-owner sources. The difference between net loss and comprehensive loss for the years ended December 31, 2021, 2022 and 2023 was comprised of the Company’s foreign currency translation adjustments and unrealized gains and losses on available-for-sale securities.

Concentration of Credit Risk

Credit is extended to all customers based on financial condition, and collateral is generally not required. Concentrations of credit risk with respect to trade receivables are limited because of the large number of customers comprising the Company’s customer base and dispersion across many different industries and geographies. Certain international customers, however, have historically been slower to pay on trade receivables. Accordingly, the Company continually monitors collections and payments from its customers and maintains a provision for estimated credit losses based upon its historical experience and any specific customer collection issues that it has identified. Although credit losses have historically been within the Company’s expectations and the provisions established, the Company cannot guarantee that it will continue to experience the same credit loss rates that it has in the past.

Recently Issued Accounting Pronouncements

In March 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-01, Leases (Topic 842): Common Control Arrangements. This ASU permits private entities with common control arrangements that may contain or be leases to use any written terms and conditions between the parties, without regard to their legal enforceability, to identify, classify and account for common control leases. In addition, all lessees (public or private), in general, amortize leasehold improvements related to a common control lease over their useful life to the common control group, regardless of the ASC 842 lease term, as long as they continue to control the use of the underlying leased asset. The ASU is effective for fiscal years, including interim periods within those years, beginning after December 15, 2023, with early adoption allowed. The adoption of this new ASU is not anticipated to have a material effect on the Company’s consolidated financial statements and related disclosures.

In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. This ASU improves financial reporting by requiring disclosure of significant segment expenses that

are regularly provided to the chief operating decision maker (“CODM”) and included with each reported measure of significant profit or loss on an annual and interim basis. This ASU also requires that a public entity disclose the title and position of the CODM and an explanation of how the CODM uses the reported measures of a segment’s profit or loss in assessing segment performance and deciding how to allocate resources. The ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. This ASU is required to be applied retrospectively for all prior periods presented in the financial statements and will likely result in additional disclosures when adopted. The Company is evaluating the adoption impact of this ASU on the Company’s consolidated financial statements and related disclosures.

Summary of Significant Accounting Policies - Long-Lived Assets (Details) - USD ($) $ in Thousands	12 Months Ended			24 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Goodwill and intangible assets
Long-lived intangible impairment	$ 0	$ 0	$ 0
Total intangible assets	19,685	19,235		$ 19,685
Less accumulated amortization	(13,320)	(13,320)		(13,320)
Net intangible assets	6,365	5,915		6,365
Amortization expense			$ 500	0
Estimated amortization expense
2024	0			0
2025	200			200
2026	300			300
2027	300			300
2028	300			300
Thereafter	5,300			5,300
Customer relationships
Goodwill and intangible assets
Total intangible assets	$ 5,376	5,376		$ 5,376
Customer relationships \| Minimum
Goodwill and intangible assets
Estimated useful lives	1 year			1 year
Customer relationships \| Maximum
Goodwill and intangible assets
Estimated useful lives	8 years			8 years
Acquired contracts
Goodwill and intangible assets
Total intangible assets	$ 10,749	10,299		$ 10,749
Acquired contracts \| Minimum
Goodwill and intangible assets
Estimated useful lives	1 year			1 year
Acquired contracts \| Maximum
Goodwill and intangible assets
Estimated useful lives	50 years			50 years
Contractual Rights to Manure Feedstock
Goodwill and intangible assets
Contractual rights acquired	$ 500	400		$ 500
Contractual Rights to Manure Feedstock \| Minimum
Goodwill and intangible assets
Initial term of contractual rights acquired	20 years
Contractual Rights to Manure Feedstock \| Maximum
Goodwill and intangible assets
Initial term of contractual rights acquired	50 years
Trademark and trade names
Goodwill and intangible assets
Total intangible assets	$ 2,700	2,700		$ 2,700
Trademark and trade names \| Minimum
Goodwill and intangible assets
Estimated useful lives	2 years			2 years
Trademark and trade names \| Maximum
Goodwill and intangible assets
Estimated useful lives	10 years			10 years
Non-compete agreements
Goodwill and intangible assets
Estimated useful lives	3 years			3 years
Total intangible assets	$ 860	$ 860		$ 860

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of inventories

Inventories consisted of the following as of December 31, 2022 and 2023 (in thousands):


	2022		2023
Raw materials and spare parts	$	37,144	$	45,335
Total inventory	$	37,144	$	45,335

Schedule of finite-lived intangible assets

The Company’s intangible assets as of December 31, 2022 and 2023 were as follows (in thousands):


	2022		2023
Customer relationships	$	5,376	$	5,376
Acquired contracts		10,299		10,749
Trademark and trade names		2,700		2,700
Non-compete agreements		860		860
Total intangible assets		19,235		19,685
Less accumulated amortization		(13,320)		(13,320)
Net intangible assets	$	5,915	$	6,365

Schedule of goodwill

The following table summarizes the activity related to the carrying amount of goodwill (in thousands):


Balance as of December 31, 2021	$	64,328
Balance as of December 31, 2022	$	64,328
Balance as of December 31, 2023	$	64,328

- Definition

Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 350
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-Name Accounting Standards Codification
-Section 55
-Paragraph 24
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482573/350-20-50-2

+ Details

Revenue from Contracts with Customers - Tourmaline Joint Development (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 425,159	$ 420,164	$ 255,646
Operating loss	(76,400)	$ (51,707)	$ (95,048)
Tourmaline Joint Development \| Tourmaline Oil Corp.
Disaggregation of Revenue [Line Items]
Revenue	322
Gross profit	98
Operating loss	$ (310)

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

+ References

+ Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
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-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Leases - Supplemental Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases
Operating cash outflows from finance leases	$ 183	$ 164
Operating cash outflows from operating leases	10,709	6,582
Financing cash outflows from finance leases	1,055	945
Assets obtained in exchange for new finance lease liabilities	1,569	774
ROU assets obtained in exchange for operating lease liabilities	$ 46,592	$ 13,449
Weighted-average remaining lease term - finance leases	2 years 5 months 8 days	2 years 4 months 2 days
Weighted-average remaining lease term - operating leases	10 years 1 month 20 days	11 years 3 months 14 days
Weighted-average discount rate - finance leases	7.41%	5.71%
Weighted-average discount rate - operating leases	9.82%	8.44%

Debt - Aggregate Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Summary of aggregate maturities of debt obligations
2024	$ 38
2025	44
2026	50
2027	57
2028	66
Thereafter	300,000
Total debt	300,255	$ 150,093
Stonepeak Term Loan
Summary of aggregate maturities of debt obligations
2024	0
2025	0
2026	0
2027	0
2028	0
Thereafter	300,000
Total debt	300,000
Other debt
Summary of aggregate maturities of debt obligations
2024	38
2025	44
2026	50
2027	57
2028	66
Thereafter	0
Total debt	$ 255	$ 93

Land, Property and Equipment

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Land, Property and Equipment

Note 10 —Land, Property and Equipment

Land, property and equipment, net as of December 31, 2022 and 2023 consisted of the following (in thousands):


	2022		2023
Land	$	3,476	$	7,397
LNG liquefaction plants		94,790		96,786
Station equipment		353,104		418,647
Trailers		73,253		70,542
Other equipment		106,184		105,137
Construction in progress		91,105		125,389
		721,912		823,898
Less accumulated depreciation		(457,844)		(492,140)
Total land, property and equipment, net	$	264,068	$	331,758

Included in “Land, property and equipment, net” are capitalized software costs of $35.3 million and $36.8 million as of December 31, 2022 and 2023, respectively. Accumulated amortization of the capitalized software costs are $32.1 million and $34.0 million as of December 31, 2022 and 2023, respectively.

The Company recorded amortization expense related to the capitalized software costs of $1.6 million, $1.7 million and $1.9 million for the years ended December 31, 2021, 2022 and 2023, respectively.

As of December 31, 2022 and 2023, $12.9 million and $10.2 million, respectively, are included in “Accounts payable” and “Accrued liabilities” in the accompanying consolidated balance sheets, representing amounts related to purchases of property and equipment. These amounts are excluded from the accompanying consolidated statements of cash flows as they are non-cash investing activities.

The Pickens Plant was offline for maintenance and repairs during the year ended December 31, 2023; as a result, the Company recognized $3.9 million of business interruption insurance recoveries for the period, which was included in “Selling, general and administrative” expense in the consolidated statements of operations for the year ended December 31, 2023.

Fueling Station Equipment Removal

The Company was requested by Pilot Travel Centers LLC (“Pilot”) to remove LNG station equipment at select Pilot locations to accommodate Pilot making physical changes to the premises. The premises, where the affected fueling stations are located, were secured by long-term lease agreements between Pilot and the Company pursuant to which the Company had contractual rights to operate its fueling stations until the expiration of the respective leases. However, in July 2022, the Company entered into an amendment (the “Amendment”) to the Liquefied Natural Gas Fueling Station and LNG Master Sales Agreement between Pilot and Clean Energy, dated August 2, 2010, to decommission and remove LNG station

equipment from the premises where the affected fueling stations are located in accordance with a phased removal schedule beginning in the third quarter of 2022. Subsequently, all removal and decommissioning activities at these selected sites were completed by the end of the third quarter of 2023.

Reportable Segments and Geographic Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Geographic Information
Total revenue	$ 425,159	$ 420,164	$ 255,646
Total operating income (loss)	(76,400)	(51,707)	(95,048)
Total long-lived assets	661,224	527,584	441,400
United States
Geographic Information
Total revenue	418,754	416,975	252,310
Total operating income (loss)	(75,163)	(50,796)	(94,157)
Total long-lived assets	657,397	525,682	440,770
Canada
Geographic Information
Total revenue	6,405	3,189	3,336
Total operating income (loss)	(1,237)	(911)	(891)
Total long-lived assets	$ 3,827	$ 1,902	$ 630

- Definition

+ References

+ Details

Leases - Finance and Operating Lease Asset and Liability Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Finance leases:
Land, property and equipment, gross	$ 823,898	$ 721,912
Accumulated depreciation	(492,140)	(457,844)
Total land, property and equipment, net	331,758	264,068
Current portion of finance lease obligations	$ 1,758	$ 948
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current portion of finance lease obligations	Current portion of finance lease obligations
Long-term portion of finance lease obligations	$ 1,839	$ 2,134
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term portion of finance lease obligations	Long-term portion of finance lease obligations
Total finance lease liabilities	$ 3,597	$ 3,082
Operating leases:
Operating lease right-of-use assets	$ 92,324	$ 52,586
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Operating lease right-of-use assets	Operating lease right-of-use assets
Current portion of operating lease obligations	$ 6,687	$ 4,206
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current portion of operating lease obligations	Current portion of operating lease obligations
Long-term portion of operating lease obligations	$ 89,065	$ 48,911
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term portion of operating lease obligations	Long-term portion of operating lease obligations
Total operating lease liabilities	$ 95,752	$ 53,117
Finance Leased Assets
Finance leases:
Land, property and equipment, gross	6,436	5,703
Accumulated depreciation	(3,199)	(2,895)
Total land, property and equipment, net	$ 3,237	$ 2,808

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

Use of Estimates

Amazon Warrant

Tourmaline Joint Development

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Revenue Recognition

the performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account for revenue recognition.

Product Revenue

Volume-Related

Station Construction Sales

Service Revenue

O&M Services

Other services

Basis of Presentation

Use of Estimates

Inventory

Inventories consisted of the following as of December 31, 2022 and 2023 (in thousands):


	2022		2023
Raw materials and spare parts	$	37,144	$	45,335
Total inventory	$	37,144	$	45,335

Derivative Instruments and Hedging Activities

Property and Equipment

Leases

On January 1, 2019, the Company adopted Accounting Standards Codification (“ASC”) 842, Leases, whereby leases are classified as either operating leases or finance leases.

Long-Lived Assets

There were no impairments of the Company’s long-lived assets in the years ended December 31, 2021, 2022 and 2023.

The Company’s intangible assets as of December 31, 2022 and 2023 were as follows (in thousands):


	2022		2023
Customer relationships	$	5,376	$	5,376
Acquired contracts		10,299		10,749
Trademark and trade names		2,700		2,700
Non-compete agreements		860		860
Total intangible assets		19,235		19,685
Less accumulated amortization		(13,320)		(13,320)
Net intangible assets	$	5,915	$	6,365

Goodwill

During the years ended December 31, 2021, 2022 and 2023, the Company utilized the quantitative approach and concluded that there were no impairments to goodwill.

The following table summarizes the activity related to the carrying amount of goodwill (in thousands):


Balance as of December 31, 2021	$	64,328
Balance as of December 31, 2022	$	64,328
Balance as of December 31, 2023	$	64,328

Revenue Recognition

the performance obligation. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account for revenue recognition.

Product Revenue

Volume-Related

Station Construction Sales

Service Revenue

O&M Services

Other services

Alternative Fuels Tax Credit

Alternative Fuel Excise Tax Credit

LNG Transportation Costs

The Company records the costs incurred to transport LNG to its customers in “Product cost of sales” in the accompanying consolidated statements of operations.

Advertising Costs

Advertising costs are expensed as incurred. Advertising costs were immaterial for the years ended December 31, 2021, 2022 and 2023.

Stock-Based Compensation

Amazon Warrant

Income Taxes

Net Loss Per Share

Foreign Currency Translation and Transactions

Comprehensive Loss

Concentration of Credit Risk

Recently Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Fair Value Measurements - Commodity Swap Contracts (Details) - Not Designated as Hedging Instrument - Valuation Technique, Discounted Cash Flow - Level 3	Dec. 31, 2023	Dec. 31, 2022
Commodity swaps \| Minimum \| ULSD Gulf Coast Forward Curve
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	1.97	2.35
Commodity swaps \| Minimum \| Historical Differential to PADD 3 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	0.92	0.88
Commodity swaps \| Minimum \| Historical Differential to PADD 5 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	1.89	1.89
Commodity swaps \| Maximum \| ULSD Gulf Coast Forward Curve
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	2.27	2.59
Commodity swaps \| Maximum \| Historical Differential to PADD 3 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	1.62	1.62
Commodity swaps \| Maximum \| Historical Differential to PADD 5 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	3.16	3.00
Commodity swaps \| Weighted Average \| ULSD Gulf Coast Forward Curve
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	2.15	2.48
Commodity swaps \| Weighted Average \| Historical Differential to PADD 3 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	1.16	1.13
Commodity swaps \| Weighted Average \| Historical Differential to PADD 5 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	2.48	2.30
Fueling agreements \| Minimum \| ULSD Gulf Coast Forward Curve
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	1.97	2.35
Fueling agreements \| Minimum \| Historical Differential to PADD 3 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	0.92	0.88
Fueling agreements \| Minimum \| Historical Differential to PADD 5 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	1.89	1.91
Fueling agreements \| Maximum \| ULSD Gulf Coast Forward Curve
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	2.27	2.59
Fueling agreements \| Maximum \| Historical Differential to PADD 3 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	1.62	1.62
Fueling agreements \| Maximum \| Historical Differential to PADD 5 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	3.16	3.05
Fueling agreements \| Weighted Average \| ULSD Gulf Coast Forward Curve
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	2.15	2.48
Fueling agreements \| Weighted Average \| Historical Differential to PADD 3 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	1.16	1.13
Fueling agreements \| Weighted Average \| Historical Differential to PADD 5 Diesel
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative asset, measurement input	2.48	2.31