0001628280-25-050643 | 10-Q | XBRL Viewer

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Leases - Narrative (Details) $ in Thousands	9 Months Ended
Leases - Narrative (Details) $ in Thousands	Sep. 30, 2025 USD ($) facility
Operating Leased Assets [Line Items]
Right-of-use asset carrying value	$ 5,397
Other Income
Operating Leased Assets [Line Items]
Gain recognized in other income	$ 600
RNG Fuel
Operating Leased Assets [Line Items]
Number of facilities \| facility	2

Related Parties

9 Months Ended

Sep. 30, 2025

Related Parties

Related parties are represented by Fortistar and other affiliates, subsidiaries, entities under common control with Fortistar or NextEra, and equity method investments.

Purchase and sale agreement for environmental attributes

In January 2025, the EPA implemented a new framework in which (1) RNG producers are eligible to claim a “K-1” RINs on their volumes of RNG produced, and (2) dispensers are eligible to claim “K-2” RINs on natural gas volumes dispensed as truck fuel, provided they also have a corresponding K-1 RIN to demonstrate the renewable sourcing of gas. The creation of distinct “K-1” and “K-2” RINs creates flexibility for RNG producers to generate and sell K-1 RINs to dispensers independent of the K-2 registration process or dispensing activities. K-1 RINs are only useful for the purpose of registering a K-2 RIN, and K-2 RINs are used to record the environmental offset (similar to a traditional RIN). The introduction of K-1 and K-2 RINs gives rise to a new form of commercial transaction for Opal that is distinct from previous RIN minting arrangements.

On March 26, 2025, the Company entered into a NAESB Base Contract with NextEra (together with certain special conditions, a letter agreement, and an RNG addendum, the "NAESB Contract"). In accordance with the NAESB Contract, the Company could enter into transaction confirmations on a periodic basis for the sale of RNG generated by the RNG Fuels business and NextEra could elect to utilize the Company to market such RNG to generate RINs for NextEra. In March, June and September 2025, the Company and NextEra entered into such transaction confirmations.

The Company concluded that production and dispensing services represent separate performance obligations. Control over K-1 RINs transfers at the time of gas generation or upon delivery of the RINs. Revenue is recognized at the time control is transferred. The consideration associated with dispensing services is recognized into revenue by the Company when it satisfies its performance obligation by pairing the paperwork associated with the dispensing.

For the three and nine months ended September 30, 2025, the Company recognized revenues of $4,982 and $15,585, respectively, under the NAESB contract, which were recorded as part of Revenues - RNG Fuel.

Service agreements with related parties

On March 17, 2025, Fortistar, through its subsidiary Wasatch RNG LLC (“Wasatch RNG”), acquired all of the limited liability company interests outstanding in Alpro SD, LLC (“Alpro” and such acquired interest, the “Alpro Interest”). Alpro owns a 50% limited liability company interest in Wasatch Resource Recovery, LLC (the “Project” or “Wasatch” and such ownership interest, the “Wasatch Interest”) and a 50% tenancy-in-common interest in certain real estate and operating assets used by Wasatch (the “Project Interest”). The Project captures and converts biogas generated from food waste to produce pipeline quality RNG. The Project generates revenue from long-term contracted gas sales, tipping fees, and digestate (fertilizer) sales.

In connection with the acquisition, Fortistar Services 2 LLC and OPAL Fuels LLC entered into an amendment to its existing Administrative Services Agreement, pursuant to which OPAL Fuels will provide certain services to Wasatch RNG in exchange for certain agreed upon fees and expense reimbursements. These services include oversight of the plan to improve the operations and productivity of the Project. Either party may, at its sole election and on ninety (90) days advance written notice, terminate Company's provision of services to Wasatch, at which time the Management Fee and the Wasatch Remediation Fee shall also terminate.

Additionally, Wasatch RNG and OPAL Fuels entered into an Option Agreement, pursuant to which Wasatch RNG granted an option to OPAL Fuels to purchase the Alpro Interest. The exercise period of the option commenced upon closing of the acquisition and will terminate on the third anniversary of the closing of the acquisition, or ninety (90) days following a change of control of OPAL Fuels. The exercise price of the option would be determined such that Wasatch RNG would earn an internal rate of return on its invested capital of 10% percent per year if the option is exercised in the first year, 15% per year if exercised in the second year, and 20% per year if exercised in the third year.

Wasatch RNG is determined to be a VIE due to their having insufficient equity investment at risk to finance their activities without additional subordinated financial support, and due to the fact that the holder of equity at risk in Wasatch RNG lacks the right to fully receive the expected residual returns. However, we are not the primary beneficiary of this VIE because we do not have the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance. Accordingly, we do not consolidate the results of operations, financial condition and cash flows of Wasatch RNG in our condensed consolidated financial statements.

During the first quarter of 2025, Scott Contino, CFO of Fortistar, served as Interim CFO of the Company. Pursuant to the Interim Services Agreement, the Company paid Fortistar an agreed hourly rate, such that the monthly fee did not exceed $50, on a cumulative basis.

The following table summarizes revenues recorded from related parties:


	Three Months Ended September 30, 2025						Nine Months Ended September 30, 2025
	RNG fuel		Fuel Station Services		Renewable Power		RNG fuel		Fuel Station Services		Renewable Power
Environmental Attributes (1)	$	17,825	$	9,198	$	—	$	55,658	$	34,653	$	—
Commodity swaps (2)	—		—		2,022		—		—		4,676
Environmental processing (3)	—		2,294		—		—		6,268		—
Service agreements (4)	125		—		—		271		—		—
Total	$	17,950	$	11,492	$	2,022	$	55,929	$	40,921	$	4,676


	Three Months Ended September 30, 2024						Nine months ended September 30, 2024
	RNG fuel		Fuel Station Services		Renewable Power		RNG fuel		Fuel Station Services		Renewable Power
Environmental Attributes (1)	$	22,798	$	10,616	$	—	$	54,174	$	27,885	$	—
Commodity swaps (2)	—		—		1,799		—		—		5,129
Environmental processing (3)	—		1,910		—		—		6,349		—
Total	$	22,798	$	12,526	$	1,799	$	54,174	$	34,234	$	5,129

(1) Represents RIN and LCFS sales to NextEra.

(2) Represents revenue earned under ISDA and REC sales agreements with NextEra.

(3) Represents environmental processing fees earned under agreements with equity method investments, related to the generation and marketing of RINs and LCFS.

(4) Represents management fees earned under an agreement with Fortistar.

The following table summarizes the various fees recorded under the service agreements with related parties which are included in "Selling, general, and administrative" expenses:


	Three Months Ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
Staffing and management services	$	447	$	535	$	1,557	$	1,531
Rent - fixed compensation	187		181		535		524
IT services	692		814		2,723		2,318
Total	$	1,326	$	1,530	$	4,815	$	4,373

The following table presents the various balances for related parties included in our condensed consolidated balance sheets as of September 30, 2025 and December 31, 2024:


	Location in Balance Sheet	September 30 2025		December 31 2024
Assets:
Trade AR - NextEra	Accounts receivable, related party	$	21,645	$	14,522
Receivables from equity method investment entities	Accounts receivable, related party	46		—
Total receivables - related party		21,691		14,522
Liabilities:
Payables to equity method investment entities	Accounts payable, related party	6,860		6,946
NextEra	Accounts payable, related party	500		501
Fortistar and Costar (1)	Accounts payable, related party	65		485
Total liabilities - related party		$	7,425	$	7,932

(1) Includes staffing, management and IT services.

Class D Common Stock Conversion

On April 23, 2025, our ultimate controlling shareholder, Fortistar, through its subsidiary OPAL Holdco LLC, exchanged 50 million shares of Class D common stock of the Company held by it, each of which is entitled to five votes per share on all matters on which stockholders generally are entitled to vote, for an equal number of shares of newly issued Class B common stock of the Company, each of which is entitled to one vote on such matters. This transaction had no effect on the economic interest in the Company held by Fortistar.

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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 5
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-URI https://asc.fasb.org/1943274/2147480990/946-20-50-5

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147480990/946-20-50-6

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Paragraph 2
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
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-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 BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Current assets:
Cash and cash equivalents (includes $119 and $358 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	$ 29,928	$ 24,310
Accounts receivable, net of allowances of $2,454 and $—, respectively (includes $17 and $435 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	31,113	32,013
Restricted cash - current (includes $906 and $972 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	1,077	972
Fuel tax credits receivable	3,264	5,639
Contract assets	12,646	11,075
Parts inventory	12,082	10,294
Prepaid expense and other current assets (includes $1,100 and $144 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	10,984	18,363
Total current assets	122,785	117,188
Property, plant, and equipment, net (includes $30,931 and $25,428 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	484,351	458,258
Investment in other entities	227,545	223,594
Other long-term assets	24,182	23,483
Restricted cash - non-current (includes $2,633 and $2,315 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	3,278	3,946
Goodwill	54,608	54,608
Total assets	916,749	881,077
Current liabilities:
Fuel tax credits payable	3,069	4,422
Accrued payroll (includes $39 and $45 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	8,611	9,580
Accrued and payable capital expenditures	10,014	23,238
Accrued environmental credit rebates	4,593	5,391
Accrued expenses and other current liabilities (includes $1,148 and $974 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	14,880	14,717
Contract liabilities	8,378	9,276
OPAL Term Loan - current portion	9,349	10,865
Sunoma Loan - current portion (includes $1,861 and $1,756 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	1,861	1,756
Total current liabilities	83,461	103,596
OPAL Term Loan, net of debt issuance costs	313,324	266,630
Sunoma Loan, net of debt issuance costs (includes $17,071 and $18,373 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	17,071	18,373
Operating lease liabilities - non-current portion	11,940	12,155
Other long-term liabilities (includes $1,307 and $2,495 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	8,157	15,291
Total liabilities	433,953	416,045
Commitments and contingencies Note 12
Stockholders' equity (deficit)
Retained earnings (accumulated deficit)	19,089	(137,004)
Accumulated other comprehensive (loss) income	(12)	152
Class A common stock in treasury, at cost; 1,635,783 at September 30, 2025 and December 31, 2024	(11,614)	(11,614)
Total Stockholders' equity (deficit) attributable to the Company	7,480	(148,449)
Non-redeemable non-controlling interests	2,788	618
Total Stockholders' equity (deficit)	10,268	(147,831)
Total liabilities, Redeemable preferred non-controlling interests, Redeemable non-controlling interests and Stockholders' equity (deficit)	916,749	881,077
Redeemable preferred non-controlling interests
Current liabilities:
Redeemable non-controlling interests	130,000	130,000
Redeemable non-controlling interests
Current liabilities:
Redeemable non-controlling interests	342,528	482,863
Class A Common Stock
Stockholders' equity (deficit)
Common stock	3	3
Class B Common Stock
Stockholders' equity (deficit)
Common stock	12	7
Class C common stock
Stockholders' equity (deficit)
Common stock	0	0
Class D Common Stock
Stockholders' equity (deficit)
Common stock	2	7
Nonrelated Party
Current assets:
Accounts receivable, net of allowances of $2,454 and $—, respectively (includes $17 and $435 at September 30, 2025 and December 31, 2024, respectively, related to consolidated VIEs)	31,113	32,013
Current liabilities:
Accounts payable	15,281	16,419
Related Party
Current assets:
Accounts receivable, related party	21,691	14,522
Current liabilities:
Accounts payable	$ 7,425	$ 7,932

Derivative Financial Instruments and Fair Value Measurements - Effect of Commodity Swaps for Derivative Instruments on Statement of Operations (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Commodity Contract
Derivative [Line Items]
Total realized and unrealized gain	$ 1,362	$ 30	$ 2,768	$ 115
Renewable Power
Derivative [Line Items]
Commodity swaps - realized gain (loss)	8	200	(52)	609
Commodity swaps - unrealized gain (loss)	12	(170)	0	(494)
RNG Fuel
Derivative [Line Items]
Commodity swaps - realized gain (loss)	1,029	0	1,900	0
Commodity swaps - unrealized gain (loss)	$ 313	$ 0	$ 920	$ 0

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Cash and cash equivalent	$ 29,928	$ 24,310
Accounts receivable, net	31,113	32,013
Restricted cash - current	1,077	972
Prepaid expenses and other current assets	10,984	18,363
Property, plant and equity, net	484,351	458,258
Restricted cash - non-current	3,278	3,946
Accrued payroll	8,611	9,580
Accrued expenses and other current liabilities	14,880	14,717
Secured debt, current	1,861	1,756
Sunoma Loan, net of debt issuance costs	17,071	18,373
Other long-term liabilities	$ 8,157	$ 15,291
Class A common stock, in treasury, at cost (in shares)	1,635,783	1,635,783
Class A Common Stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	340,000,000	340,000,000
Common stock, shares issued (in shares)	30,631,960	30,065,260
Common stock, shares outstanding (in shares)	28,996,177	28,429,477
Class B Common Stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	160,000,000	160,000,000
Common stock, shares issued (in shares)	121,500,000	71,500,000
Common stock, shares outstanding (in shares)	121,500,000	71,500,000
Class C common stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	160,000,000	160,000,000
Common stock, shares issued (in shares)	0	0
Common stock, shares outstanding (in shares)	0	0
Class D Common Stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	160,000,000	160,000,000
Common stock, shares issued (in shares)	22,899,037	72,899,037
Common stock, shares outstanding (in shares)	22,899,037	72,899,037
Nonrelated Party
Accounts receivable, net	$ 31,113	$ 32,013
Accounts payable	15,281	16,419
Related Party
Accounts payable	7,425	7,932
Primary Beneficiary
Cash and cash equivalent	119	358
Accounts receivable, net	17	435
Restricted cash - current	906	972
Prepaid expenses and other current assets	1,100	144
Property, plant and equity, net	30,931	25,428
Restricted cash - non-current	2,633	2,315
Accrued payroll	39	45
Accrued expenses and other current liabilities	1,148	974
Secured debt, current	1,861	1,756
Sunoma Loan, net of debt issuance costs	17,071	18,373
Other long-term liabilities	1,307	2,495
Primary Beneficiary \| Nonrelated Party
Accounts receivable, net	2,454	0
Accounts payable	178	22
Primary Beneficiary \| Related Party
Accounts payable	$ 83	$ 426

Reportable Segments and Geographic Information - Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	$ 83,357	$ 84,047	$ 249,220	$ 219,949
Cost of sales and other operating costs	69,779	62,083	215,067	181,485
Income from equity method investments	(637)	(3,822)	(1,877)	(11,828)
Interest and financing expense, net	6,898	5,026	19,330	13,976
Project development and startup costs	2,543	6,803	12,101	10,523
Other income		(360)	(879)	(360)
Depreciation, amortization, and accretion	5,566	4,697	16,772	12,677
Other segment items	2,389	1,419	4,767	2,690
Segment income (loss)	(3,181)	8,201	(16,061)	10,786
Income tax benefit	14,567	8,906	36,290	8,906
Net income	11,386	17,107	20,229	19,692
Investment in other entities	227,545		227,545		$ 223,594
Segment assets	916,749		916,749		881,077
Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	(5,533)	(4,649)	(15,094)	(15,447)
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	83,357	84,047	249,220	219,949
Cost of sales and other operating costs	57,921	51,368	173,602	147,457
Income from equity method investments	(637)	(3,822)	(1,877)	(11,828)
Interest and financing expense, net	6,898	5,026	19,330	13,976
Project development and startup costs	2,543	6,803	12,101	10,523
Other income		(349)	(64)	(349)
Depreciation, amortization, and accretion	5,566	4,697	16,772	12,677
Other segment items	55	(447)	(1,290)	(1,043)
Segment income (loss)	11,011	20,771	30,646	48,536
Investment in other entities	227,545		227,545		223,594
Segment assets	876,135		876,135		845,748
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	0	0	0	0
Cost of sales and other operating costs	11,858	10,715	41,465	34,028
Income from equity method investments	0	0	0	0
Interest and financing expense, net	0	0	0	0
Project development and startup costs	0	0	0	0
Other income		(11)	(815)	(11)
Depreciation, amortization, and accretion	0	0	0	0
Other segment items	2,334	1,866	6,057	3,733
Investment in other entities	0		0		0
Segment assets	40,614		40,614		35,329
Corporate and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	0	0	0	0
Segment income (loss)	(14,192)	(12,570)	(46,707)	(37,750)
RNG Fuel
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	22,921	25,864	75,650	63,036
RNG Fuel \| Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	(139)	(129)	(415)	(388)
RNG Fuel \| Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	22,921	25,864	75,650	63,036
Cost of sales and other operating costs	11,774	9,985	35,341	26,644
Income from equity method investments	(637)	(3,822)	(1,877)	(11,828)
Interest and financing expense, net	6,929	4,958	19,333	13,969
Project development and startup costs	2,543	6,803	12,101	10,523
Other income		0	0	0
Depreciation, amortization, and accretion	3,031	2,124	8,985	5,482
Other segment items	(27)	(300)	(214)	(627)
Segment income (loss)	(692)	6,116	1,981	18,873
Investment in other entities	227,545		227,545		223,594
Segment assets	660,922		660,922		635,927
Fuel Station Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	51,722	45,395	149,426	121,794
Fuel Station Services \| Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	(5,394)	(4,520)	(14,679)	(15,059)
Fuel Station Services \| Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	51,722	45,395	149,426	121,794
Cost of sales and other operating costs	40,230	33,609	118,683	94,882
Income from equity method investments	0	0	0	0
Interest and financing expense, net	(11)	95	45	119
Project development and startup costs	0	0	0	0
Other income		0	0	0
Depreciation, amortization, and accretion	1,573	1,574	4,924	4,183
Other segment items	81	(145)	(1,076)	(443)
Segment income (loss)	9,849	10,262	26,850	23,053
Investment in other entities	0		0		0
Segment assets	184,555		184,555		179,304
Renewable Power
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	8,714	12,788	24,144	35,119
Renewable Power \| Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	0	0	0	0
Renewable Power \| Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	8,714	12,788	24,144	35,119
Cost of sales and other operating costs	5,917	7,774	19,578	25,931
Income from equity method investments	0	0	0	0
Interest and financing expense, net	(20)	(27)	(48)	(112)
Project development and startup costs	0	0	0	0
Other income		(349)	(64)	(349)
Depreciation, amortization, and accretion	962	999	2,863	3,012
Other segment items	1	(2)	0	27
Segment income (loss)	1,854	$ 4,393	1,815	$ 6,610
Investment in other entities	0		0		0
Segment assets	$ 30,658		$ 30,658		$ 30,517

Borrowings (Tables)

9 Months Ended

Sep. 30, 2025

Debt Disclosure [Abstract]

Schedule of Borrowings

The following table summarizes the borrowings under the various debt facilities as of September 30, 2025 and December 31, 2024:


	September 30, 2025		December 31, 2024
OPAL Term Loan and Revolving Loan	$	331,618	$	286,617
Less: unamortized debt issuance costs	(8,945)		(9,122)
Less: current portion	(9,349)		(10,865)
OPAL Term Loan and Revolving Loan, net of debt issuance costs	313,324		266,630
Sunoma Loan	19,539		20,846
Less: unamortized debt issuance costs	(607)		(717)
Less: current portion	(1,861)		(1,756)
Sunoma Loan, net of debt issuance costs	17,071		18,373
Non-current borrowings total	$	330,395	$	285,003

Schedule of Principal Maturities of Debt

As of September 30, 2025, principal maturities of debt are expected as follows, excluding any undrawn debt facilities as of the date of the condensed consolidated balance sheets:


	OPAL Term Loan		Sunoma Loan		Total
Fiscal year:
Three months ending December 31, 2025	$	—	$	449	$	449
2026	12,465		1,898		14,363
2027	12,465		2,051		14,516
2028	306,688		2,213		308,901
2029	—		2,395		2,395
2030	—		2,589		2,589
Thereafter	—		7,944		7,944
	$	331,618	$	19,539	$	351,157

Schedule of Interest Expense on Borrowings

The following table summarizes the Company's total interest expense for the three and nine months ended September 30, 2025 and 2024:


	Three Months Ended September 30, 2025				Nine Months Ended September 30,
	2025		2024		2025		2024
Sunoma Loan	$	420	$	429	$	1,228	$	1,330
OPAL Term Loan (1)	5,568		4,023		15,879		10,341
Commitment fees and other finance fees	449		667		1,405		2,141
Amortization of deferred financing cost	722		191		1,524		1,310
Interest expense on finance leases	25		144		235		432
Interest income	(286)		(428)		(941)		(1,578)
Total interest and financing expense	$	6,898	$	5,026	$	19,330	$	13,976

(1) Excludes $841 and $1,019 of interest capitalized and recorded as part of Property, Plant and Equipment for the three months ended September 30, 2025 and 2024. Excludes $2,082 and $3,093 of interest capitalized and recorded as part of Property, Plant and Equipment for the nine months ended September 30, 2025 and 2024

Reportable Segments and Geographic Information - Capital Expenditures (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting, Revenue Reconciling Item [Line Items]
Cash paid for purchases of property, plant and equipment	$ 60,890	$ 72,805
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Cash paid for purchases of property, plant and equipment	60,890	72,805
Operating Segments \| RNG fuel
Segment Reporting, Revenue Reconciling Item [Line Items]
Cash paid for purchases of property, plant and equipment	44,259	56,195
Operating Segments \| Fuel Station Services
Segment Reporting, Revenue Reconciling Item [Line Items]
Cash paid for purchases of property, plant and equipment	16,140	16,610
Operating Segments \| Renewable Power
Segment Reporting, Revenue Reconciling Item [Line Items]
Cash paid for purchases of property, plant and equipment	491	0
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Cash paid for purchases of property, plant and equipment	$ 0	$ 0

Net Income Per Share - Basic and Diluted Net Income Per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Earnings Per Share [Abstract]
Net income attributable to Class A common stockholders	$ 1,450	$ 2,362	$ 2,015	$ 1,893
Weighted average number of shares of Class A common stock - basic (in shares)	28,279,527	27,709,203	28,090,014	27,585,620
Dilutive effect of stock options and restricted stock units (in shares)	1,313,295	34,214	923,691	58,544
Weighted average number of shares of Class A common stock - diluted (in shares)	29,592,822	27,743,417	29,013,705	27,644,164
Net income per share of Class A common stock
Basic (in dollars per share)	$ 0.05	$ 0.09	$ 0.07	$ 0.07
Diluted (in dollars per share)	$ 0.05	$ 0.09	$ 0.07	$ 0.07

- Definition

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

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- 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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- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

+ Details

Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2025

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments - Operating Leases

The table below provides the total amount of lease payments on an undiscounted basis on our lease contracts as of September 30, 2025:


	Site leases		Office leases		Vehicle and Equipment leases		Total

Three months ending December 31, 2025	$	261	$	141	$	403	$	805
2026	1,044		47		1,529		2,620
2027	1,094		—		1,035		2,129
2028	1,129		—		347		1,476
2029	1,129		—		—		1,129
2030	1,129		—		—		1,129
Thereafter	18,267		—		—		18,267
	$24,053		$188		$3,314		$27,555

Schedule of Future Minimum Lease Payments - Finance Leases

The table below provides the total amount of lease payments on an undiscounted basis on our lease contracts as of September 30, 2025:


	Site leases		Office leases		Vehicle and Equipment leases		Total

Three months ending December 31, 2025	$	261	$	141	$	403	$	805
2026	1,044		47		1,529		2,620
2027	1,094		—		1,035		2,129
2028	1,129		—		347		1,476
2029	1,129		—		—		1,129
2030	1,129		—		—		1,129
Thereafter	18,267		—		—		18,267
	$24,053		$188		$3,314		$27,555

Related Parties - Revenues Recorded from Related Parties (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Related Party Transaction [Line Items]
Total revenues	$ 83,357	$ 84,047	$ 249,220	$ 219,949
RNG fuel
Related Party Transaction [Line Items]
Total revenues	22,921	25,864	75,650	63,036
Fuel Station Services
Related Party Transaction [Line Items]
Total revenues	51,722	45,395	149,426	121,794
Renewable Power
Related Party Transaction [Line Items]
Total revenues	8,714	12,788	24,144	35,119
Related Party \| RNG fuel
Related Party Transaction [Line Items]
Total revenues	17,950	22,798	55,929	54,174
Related Party \| Fuel Station Services
Related Party Transaction [Line Items]
Total revenues	11,492	12,526	40,921	34,234
Related Party \| Renewable Power
Related Party Transaction [Line Items]
Total revenues	2,022	1,799	4,676	5,129
Environmental Attributes \| Related Party \| RNG fuel
Related Party Transaction [Line Items]
Total revenues	17,825	22,798	55,658	54,174
Environmental Attributes \| Related Party \| Fuel Station Services
Related Party Transaction [Line Items]
Total revenues	9,198	10,616	34,653	27,885
Environmental Attributes \| Related Party \| Renewable Power
Related Party Transaction [Line Items]
Total revenues	0	0	0	0
Commodity Swaps \| Related Party \| RNG fuel
Related Party Transaction [Line Items]
Total revenues	0	0	0	0
Commodity Swaps \| Related Party \| Fuel Station Services
Related Party Transaction [Line Items]
Total revenues	0	0	0	0
Commodity Swaps \| Related Party \| Renewable Power
Related Party Transaction [Line Items]
Total revenues	2,022	1,799	4,676	5,129
Environmental Processing Fees \| Related Party \| RNG fuel
Related Party Transaction [Line Items]
Total revenues	0	0	0	0
Environmental Processing Fees \| Related Party \| Fuel Station Services
Related Party Transaction [Line Items]
Total revenues	2,294	1,910	6,268	6,349
Environmental Processing Fees \| Related Party \| Renewable Power
Related Party Transaction [Line Items]
Total revenues	0	$ 0	0	$ 0
Service Agreements \| Related Party \| RNG fuel
Related Party Transaction [Line Items]
Service agreements	125		271
Service Agreements \| Related Party \| Fuel Station Services
Related Party Transaction [Line Items]
Service agreements	0		0
Service Agreements \| Related Party \| Renewable Power
Related Party Transaction [Line Items]
Service agreements	$ 0		$ 0

Borrowings - Principal Maturities of Debt (Details) $ in Thousands	Sep. 30, 2025 USD ($)
Debt Instrument [Line Items]
Three months ending December 31, 2025	$ 449
2026	14,363
2027	14,516
2028	308,901
2029	2,395
2030	2,589
Thereafter	7,944
Total	351,157
OPAL Term Loan
Debt Instrument [Line Items]
Three months ending December 31, 2025	0
2026	12,465
2027	12,465
2028	306,688
2029	0
2030	0
Thereafter	0
Total	331,618
Sunoma Loan
Debt Instrument [Line Items]
Three months ending December 31, 2025	449
2026	1,898
2027	2,051
2028	2,213
2029	2,395
2030	2,589
Thereafter	7,944
Total	$ 19,539

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Statement of Cash Flows [Abstract]
Interest capitalized	$ 841	$ 1,019	$ 2,082	$ 3,093

Redeemable non-controlling interests, Redeemable preferred non-controlling interests and Stockholders' Equity (Deficit) (Tables)

9 Months Ended

Sep. 30, 2025

Equity [Abstract]

Schedule of Changes in Redeemable Preferred Units

The following table summarizes the changes in the redeemable preferred non-controlling interests which represent Series A and Series A-1 preferred units outstanding at OPAL Fuels LLC (a consolidated subsidiary of the Company) from December 31, 2024 to September 30, 2025:


	Series A-1 preferred units			Series A preferred units
	Units	Amount		Units	Amount		Total
Balance, December 31, 2024	300,000	$	30,000	1,000,000	$	100,000	$	130,000
Preferred dividends attributable to Redeemable non-controlling interest	—	1,509		—	5,029		6,538
Preferred dividends attributable to Class A common stockholders	—	303		—	1,010		1,313
Payment of preferred dividends	—	(1,812)		—	(6,039)		(7,851)
Balance, September 30, 2025	300,000	$	30,000	1,000,000	$	100,000	$	130,000

- Definition

Tabular disclosure of temporary equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

+ References + Details

Net Income Per Share

9 Months Ended

Sep. 30, 2025

Earnings Per Share [Abstract]

Net Income Per Share

The following table summarizes the calculation of basic and diluted net income per share:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Net income attributable to Class A common stockholders	$	1,450	$	2,362	$	2,015	$	1,893

Weighted average number of shares of Class A common stock - basic	28,279,527		27,709,203		28,090,014		27,585,620
Dilutive effect of stock options and restricted stock units	1,313,295		34,214		923,691		58,544
Weighted average number of shares of Class A common stock - diluted	29,592,822		27,743,417		29,013,705		27,644,164
Net income per share of Class A common stock
Basic	$	0.05	$	0.09	$	0.07	$	0.07
Diluted	$	0.05	$	0.09	$	0.07	$	0.07

The basic income per share for the three and nine months ended September 30, 2025 does not include 1,635,783 shares in treasury and 716,650 shares that are issued and outstanding but are contingent on achieving earnout targets.

The following table presents the forms of antidilutive potential common shares:


	Three months ended September 30,		Nine Months Ended September 30,
	2025	2024	2025	2024
Stock options	483,502	507,121	483,502	507,121
Unvested PSUs	1,954,966	2,918,668	1,954,966	2,918,668
Unvested RSUs	1,068,958	1,558,615	1,068,958	1,564,331
OPAL Fuels Class B units	144,399,037	144,399,037	144,399,037	144,399,037

Reportable Segments and Geographic Information

9 Months Ended

Sep. 30, 2025

Segment Reporting [Abstract]

Reportable Segments and Geographic Information

The Company is organized into three operating segments based on the characteristics of its renewable power generation, dispensing portfolio, production and sale of renewable gas, and nature of other products and services.

Our reportable segments disclosure is aligned with the information and internal reporting provided to our CODM. Our Co-CEOs, Adam Comora and Jonathan Maurer, jointly fulfill the role of the CODM. The CODM evaluates performance based on segment net income (loss). For all of the segments, the CODM uses segment net income (loss) in the annual budgeting and monthly forecasting process. The CODM considers budget-to-current forecast and prior forecast-to-current forecast variances for segment net income (loss) on a monthly basis for evaluating performance of each segment and making decisions about allocating capital and other resources to each segment.

The three operating segments are RNG Fuel, Fuel Station Services and Renewable Power. The Company has determined that each of the three operating segments meets the characteristics of a reportable segment under U.S. GAAP.

The Corporate entity is not determined to be an operating segment but is discretely disclosed for purposes of reconciliation of the Company’s consolidated financial statements, and though not denoted as an operating segment, significant expenses are noted within the segment.

The following table reflects the financial data used to calculate each reportable segment’s net income (loss) and includes reconciliations to Opal’s consolidated revenue and consolidated net income (loss) for the three and nine months ended September 30, 2025:


Nine Months Ended September 30, 2025	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Revenue from external customers	$	75,650	$	149,426	$	24,144	$	249,220	$	—	$	249,220
Intersegment revenues	415		14,679		—		15,094		—		15,094

Reconciliation of Revenue
Elimination of intersegment revenues	(415)		(14,679)		—		(15,094)		—		(15,094)
Total revenues	75,650		149,426		24,144		249,220		—		249,220

Less: (1)
Cost of sales and other operating costs	35,341		118,683		19,578		173,602		41,465		215,067
Income from equity method investments	(1,877)		—		—		(1,877)		—		(1,877)
Interest and financing expense, net	19,333		45		(48)		19,330		—		19,330
Project development and startup costs	12,101		—		—		12,101		—		12,101
Other income	—		—		(64)		(64)		(815)		(879)
Depreciation, amortization, and accretion	8,985		4,924		2,863		16,772		—		16,772
Other segment items (2)	(214)		(1,076)		—		(1,290)		6,057		4,767
Segment income (loss)	1,981		26,850		1,815		30,646		(46,707)		(16,061)

Reconciliation of profit or loss (segment income / (loss))
Income tax benefit											36,290
Net income											$	20,229


Three Months Ended September 30, 2025	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Revenue from external customers	$	22,921	$	51,722	$	8,714	$	83,357	$	—	$	83,357
Intersegment revenues	139		5,394		—		5,533		—		5,533

Reconciliation of Revenue
Elimination of intersegment revenues	(139)		(5,394)		—		(5,533)		—		(5,533)
Total revenues	22,921		51,722		8,714		83,357		—		83,357

Less: (1)
Cost of sales and other operating costs	11,774		40,230		5,917		57,921		11,858		69,779
Income from equity method investments	(637)		—		—		(637)		—		(637)
Interest and financing expense, net	6,929		(11)		(20)		6,898		—		6,898
Project development and startup costs	2,543		—		—		2,543		—		2,543

Depreciation, amortization, and accretion	3,031		1,573		962		5,566		—		5,566
Other segment items (2)	(27)		81		1		55		2,334		2,389
Segment (loss) income	(692)		9,849		1,854		11,011		(14,192)		(3,181)

Reconciliation of profit or loss (segment income / (loss))
Income tax benefit											14,567
Net income											$	11,386

(1) The significant expense categories and amounts align with the segment-level information that is regularly provided to the chief operating decision maker. Intersegment expenses are included within the amounts shown.

(2) Other segment items for each reportable segment includes:

•Fuel Station Services - gain on RNG dispensing, and gain on asset disposal

•Corporate - information technology expense, legal and professional advisor fees, and other overhead expenses

Geographic Information: The Company's assets and revenue generating activities are domiciled in the United States.

The following table reflects certain other financial data for the reportable segments as of September 30, 2025:


	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Other segment disclosures
Investment in other entities	$	227,545	$	—	$	—	$	227,545	$	—	$	227,545
Segment assets	660,922		184,555		30,658		876,135		40,614		$	916,749

For the nine months ended September 30, 2025, the Company made the following cash payments for capital expenditures:


	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Cash paid for purchases of property, plant and equipment	$	44,259	$	16,140	$	491	$	60,890	$	—	$	60,890


Nine months ended September 30, 2024	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Revenue from external customers	$	63,036	$	121,794	$	35,119	$	219,949	$	—	$	219,949
Intersegment revenues	388		15,059		—		15,447		—		15,447
							0
Reconciliation of Revenue							0
Elimination of intersegment revenues	(388)		(15,059)		—		(15,447)		—		(15,447)
Total revenues	63,036		121,794		35,119		219,949		—		219,949

Less: (1)
Cost of sales and other operating costs	26,644		94,882		25,931		147,457		34,028		181,485
Income from equity method investments	(11,828)		—		—		(11,828)		—		(11,828)
Interest and financing expense, net	13,969		119		(112)		13,976		—		13,976
Project development and startup costs	10,523		—		—		10,523		—		10,523
Other income	—		—		(349)		(349)		(11)		(360)
Depreciation, amortization, and accretion	5,482		4,183		3,012		12,677		—		12,677
Other segment items (2)	(627)		(443)		27		(1,043)		3,733		2,690
Segment income (loss)	18,873		23,053		6,610		48,536		(37,750)		10,786

Reconciliation of profit or loss (segment income / (loss))
Income tax benefit											8,906
Net income											$	19,692


Three Months Ended September 30, 2024	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Revenue from external customers	$	25,864	$	45,395	$	12,788	$	84,047	$	—	$	84,047
Intersegment revenues	129		4,520		—		4,649		—		4,649

Reconciliation of Revenue
Elimination of intersegment revenues	(129)		(4,520)		—		(4,649)		—		(4,649)
Total revenues	25,864		45,395		12,788		84,047		—		84,047

Less: (1)
Cost of sales and other operating costs	9,985		33,609		7,774		51,368		10,715		62,083
Income from equity method investments	(3,822)		—		—		(3,822)		—		(3,822)
Interest and financing expense, net	4,958		95		(27)		5,026		—		5,026
Project development and startup costs	6,803		—		—		6,803		—		6,803
Other income	—		—		(349)		(349)		(11)		(360)
Depreciation, amortization, and accretion	2,124		1,574		999		4,697		—		4,697
Other segment items (2)	(300)		(145)		(2)		(447)		1,866		1,419
Segment income (loss)	6,116		10,262		4,393		20,771		(12,570)		8,201

Reconciliation of profit or loss (segment income / (loss))
Income tax benefit											8,906
Net income											$	17,107

(2) Other segment items for each reportable segment includes:

•Fuel Station Services - gain on recognition of RINs

•Corporate - gain on mark-to-market for OPAL and Sponsor Earnout Awards, loss on extinguishment of debt, insurance other overhead expenses

Geographic Information: The Company's assets and revenue generating activities are domiciled in the United States.

The following table reflects certain other financial data for the reportable segments as of December 31, 2024:


	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Other segment disclosures
Investment in other entities	$	223,594	$	—	$	—	$	223,594	$	—	$	223,594
Segment assets	635,927		179,304		30,517		$	845,748	$	35,329	$	881,077

For the nine months ended September 30, 2024, the Company made the following cash payments for capital expenditures:


	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Cash paid for purchases of property, plant and equipment	$	56,195	$	16,610	$	—	$	72,805	$	—	$	72,805

The tables below outline the revenue from our major customer, along with respective percentages of revenue by each segment.


	Nine Months Ended September 30,
	2025				2024
Customer A	Revenue		Percentage of total revenue		Revenue		Percentage of total revenue
RNG Fuel	$	55,658	22	%	$	54,174	25	%
Fuel Station Services	34,653		14	%	27,885		13	%
Renewable Power	4,676		2	%	5,129		2	%
Total	$	94,987	38	%	$	87,188	40	%


	Three Months Ended September 30,
	2025				2024
Customer A	Revenue		Percentage of total revenue		Revenue		Percentage of total revenue
RNG Fuel	$	17,825	21	%	$	22,798	27	%
Fuel Station Services	9,198		11	%	10,616		13	%
Renewable Power	2,022		2	%	1,799		2	%
Total	$	29,045	34	%	$	35,213	42	%

Customer B was below 10% of the consolidated revenues in three and nine months ended September 30, 2025:


	Three Months Ended September 30,			Nine Months Ended September 30,
	2024			2024
Customer B	Revenue	Percentage of total revenue		Revenue	Percentage of total revenue
Fuel Station Services	11,503	14	%	31,880	14	%

- 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

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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Derivative Financial Instruments and Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jul. 31, 2024	Dec. 31, 2023
Assets:
Cash and cash equivalents and restricted cash - current and non-current	$ 34,283	$ 29,228	$ 24,194		$ 47,242
Convertible note receivable				$ 750
Fair Value, Recurring
Liabilities:
Earnout liabilities	23	304
Assets:
Cash and cash equivalents and restricted cash - current and non-current	34,283	29,228
Convertible note receivable		760
Fair Value, Recurring \| Money Market Funds
Assets:
Cash and cash equivalents and restricted cash - current and non-current	26,213	19,786
Fair Value, Recurring \| Interest rate swap contracts
Liabilities:
Commodity swap contracts	95
Assets:
Interest rate swap contracts	84	686
Fair Value, Recurring \| Commodity swap contracts
Liabilities:
Commodity swap contracts	72	72
Assets:
Commodity swap contracts	920
Fair Value, Recurring \| Level 1
Liabilities:
Earnout liabilities	0	0
Assets:
Cash and cash equivalents and restricted cash - current and non-current	34,283	29,228
Convertible note receivable		0
Fair Value, Recurring \| Level 1 \| Interest rate swap contracts
Liabilities:
Commodity swap contracts	0
Assets:
Interest rate swap contracts	0	0
Fair Value, Recurring \| Level 1 \| Commodity swap contracts
Liabilities:
Commodity swap contracts	0	0
Assets:
Commodity swap contracts	0
Fair Value, Recurring \| Level 2
Liabilities:
Earnout liabilities	0	0
Assets:
Cash and cash equivalents and restricted cash - current and non-current	0	0
Convertible note receivable		0
Fair Value, Recurring \| Level 2 \| Interest rate swap contracts
Liabilities:
Commodity swap contracts	95
Assets:
Interest rate swap contracts	84	686
Fair Value, Recurring \| Level 2 \| Commodity swap contracts
Liabilities:
Commodity swap contracts	72	72
Assets:
Commodity swap contracts	920
Fair Value, Recurring \| Level 3
Liabilities:
Earnout liabilities	23	304
Assets:
Cash and cash equivalents and restricted cash - current and non-current	0	0
Convertible note receivable		760
Fair Value, Recurring \| Level 3 \| Interest rate swap contracts
Liabilities:
Commodity swap contracts	0
Assets:
Interest rate swap contracts	0	0
Fair Value, Recurring \| Level 3 \| Commodity swap contracts
Liabilities:
Commodity swap contracts	0	$ 0
Assets:
Commodity swap contracts	$ 0

Derivative Financial Instruments and Fair Value Measurements - Effect of Interest Rate Swaps on Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gain on net periodic settlements	$ 72	$ 0	$ 217	$ 0

Stock-based compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Stock-based compensation (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation expense	$ 902	$ 1,457	$ 4,858	$ 4,312
2022 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation expense	902	1,457	4,729	4,043
Parent Equity Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation expense	$ 0	$ 0	$ 129	$ 269

- 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
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Summary of Significant Accounting Policies - Disaggregation of Revenue By Product Line (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 77,889,000	$ 82,626,000	$ 238,301,000	$ 216,392,000
Lease revenue	5,468,000	1,421,000	10,919,000	3,557,000
Total revenues	83,357,000	84,047,000	249,220,000	219,949,000
Electricity sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6,456,000	7,011,000	18,349,000	19,663,000
Third party construction
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	14,202,000	10,358,000	31,377,000	29,853,000
Service and parts
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	6,926,000	6,512,000	20,726,000	18,097,000
Brown gas sales
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	8,193,000	7,987,000	25,172,000	19,357,000
Environmental credits
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	41,567,000	50,483,000	141,431,000	128,530,000
Environmental credits \| Non-US
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	0	5,151,000	0	13,439,000
Other
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 545,000	$ 275,000	$ 1,246,000	$ 892,000

Borrowings - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
Borrowings - Narrative (Details) - USD ($) $ in Thousands	Mar. 03, 2025	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Dec. 31, 2022	Aug. 27, 2020
Sunoma Loan
Debt Instrument [Line Items]
Aggregate principal amount							$ 23,000	$ 20,000
Interest rate during period		8.70%	8.10%	8.70%	8.20%
Letter of Credit
Debt Instrument [Line Items]
Draws on letters of credit				$ 968		$ 968
Credit Agreement \| Secured Debt
Debt Instrument [Line Items]
Financing fees paid	$ 1,250
Credit Agreement \| Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Draws on letters of credit				40,000
Repayments on letters of credit				15,000
Proceeds from issuance				34,517
OPAL Term Loan \| Secured Debt
Debt Instrument [Line Items]
Debt outstanding		$ 331,618		$ 331,618		$ 286,617
Weighed average effective interest rate		8.80%	9.20%	8.50%	8.70%
OPAL Term Loan \| Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Draws on letters of credit				$ 20,000

Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands			3 Months Ended		9 Months Ended		12 Months Ended
	May 09, 2025 USD ($)	Jul. 21, 2022 shares	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) variable_interest_entity segment shares	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) shares	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Derivative [Line Items]
Number of variable interest entities \| variable_interest_entity					12
Number of operating segments \| segment					3
Product warranty accrual, current			$ 280		$ 280		$ 171
Gain (loss) on earnout awards			0	$ 278	281	$ 1,457
Business combination, contingent consideration, liability, noncurrent			23		23		$ 304
Revenue recognized included in contract liabilities					5,006	3,746
Backlog			51,484		51,484
Net proceeds from the sale of tax credits			14,567	8,906	36,290	8,906
Legal and insurance fees			$ 1,873	$ 1,182	$ 4,510	$ 1,182
Accounts Payable \| Supplier Concentration Risk \| One Vendor
Derivative [Line Items]
Concentration risk percentage					10.00%		17.00%
One Customer \| Revenue Benchmark \| Customer Concentration Risk
Derivative [Line Items]
Concentration risk percentage			34.00%		38.00%
Two Customers \| Revenue Benchmark \| Customer Concentration Risk
Derivative [Line Items]
Concentration risk percentage				56.00%		54.00%
Two Customers \| Accounts Receivable \| Customer Concentration Risk
Derivative [Line Items]
Concentration risk percentage					55.00%		50.00%
Fuel Station Services
Derivative [Line Items]
Environmental credits held for sale			$ 4,515	$ 1,443	$ 15,055	$ 8,293
Class B And D Ordinary Share \| Opal Fuels
Derivative [Line Items]
Stock issued (in shares) \| shares		144,399,037
Redeemable non-controlling interests
Derivative [Line Items]
Redeemable non-controlling interests			$ 342,528	$ 519,373	$ 342,528	$ 519,373	$ 482,863	$ 365,548	$ 276,719	$ 597,069	$ 705,190	$ 802,720
Sponsor Letter Agreement
Derivative [Line Items]
Percentage of common stock subject to vesting and forfeiture conditions		10.00%
Common stock subject to vesting and forfeiture conditions, period		60 months
Reverse recapitalization, number of shares subject to forfeiture shares (in shares) \| shares					716,650		716,650
Opal Fuels
Derivative [Line Items]
Capital contributions	$ 4,646
Third-Party Partner
Derivative [Line Items]
Capital contributions	$ 1,998
RNG Facility
Derivative [Line Items]
Subsidiary, ownership percentage, parent	70.00%
Subsidiary ownership percentage, counterparty	30.00%
Noncontrolling interest	$ 1,998

Related Parties (Tables)

9 Months Ended

Sep. 30, 2025

Schedule of Revenues Recorded from Related Parties

The following table summarizes revenues recorded from related parties:


	Three Months Ended September 30, 2025						Nine Months Ended September 30, 2025
	RNG fuel		Fuel Station Services		Renewable Power		RNG fuel		Fuel Station Services		Renewable Power
Environmental Attributes (1)	$	17,825	$	9,198	$	—	$	55,658	$	34,653	$	—
Commodity swaps (2)	—		—		2,022		—		—		4,676
Environmental processing (3)	—		2,294		—		—		6,268		—
Service agreements (4)	125		—		—		271		—		—
Total	$	17,950	$	11,492	$	2,022	$	55,929	$	40,921	$	4,676


	Three Months Ended September 30, 2024						Nine months ended September 30, 2024
	RNG fuel		Fuel Station Services		Renewable Power		RNG fuel		Fuel Station Services		Renewable Power
Environmental Attributes (1)	$	22,798	$	10,616	$	—	$	54,174	$	27,885	$	—
Commodity swaps (2)	—		—		1,799		—		—		5,129
Environmental processing (3)	—		1,910		—		—		6,349		—
Total	$	22,798	$	12,526	$	1,799	$	54,174	$	34,234	$	5,129

(1) Represents RIN and LCFS sales to NextEra.

(2) Represents revenue earned under ISDA and REC sales agreements with NextEra.

(3) Represents environmental processing fees earned under agreements with equity method investments, related to the generation and marketing of RINs and LCFS.

(4) Represents management fees earned under an agreement with Fortistar.

The following table summarizes the various fees recorded under the service agreements with related parties which are included in "Selling, general, and administrative" expenses:


	Three Months Ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
Staffing and management services	$	447	$	535	$	1,557	$	1,531
Rent - fixed compensation	187		181		535		524
IT services	692		814		2,723		2,318
Total	$	1,326	$	1,530	$	4,815	$	4,373

The following table presents the various balances for related parties included in our condensed consolidated balance sheets as of September 30, 2025 and December 31, 2024:


	Location in Balance Sheet	September 30 2025		December 31 2024
Assets:
Trade AR - NextEra	Accounts receivable, related party	$	21,645	$	14,522
Receivables from equity method investment entities	Accounts receivable, related party	46		—
Total receivables - related party		21,691		14,522
Liabilities:
Payables to equity method investment entities	Accounts payable, related party	6,860		6,946
NextEra	Accounts payable, related party	500		501
Fortistar and Costar (1)	Accounts payable, related party	65		485
Total liabilities - related party		$	7,425	$	7,932

(1) Includes staffing, management and IT services.

Derivative Financial Instruments and Fair Value Measurements - Derivatives Fair Values on Balance Sheet (Details) - Commodity Contract - Derivatives not designated as hedging instruments - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Derivatives, Fair Value [Line Items]
Prepaid expense and other current assets	$ 920	$ 0
Accrued expenses and other current liabilities	(72)	(9)
Other long-term liabilities	0	(63)
Total commodity swaps - unrealized gain (loss)	$ 848	$ (72)

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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+ Details

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
$ in Thousands

3 Months Ended

9 Months Ended

Sep. 30, 2025

Sep. 30, 2024

Sep. 30, 2025

Sep. 30, 2024

Statement of Comprehensive Income [Abstract]

Net income

$ 11,386

$ 17,107

$ 20,229

$ 19,692

Other comprehensive (loss) income

Effective portion of the cash flow hedge attributable to equity method investments

(34)

(510)

(287)

Net unrealized loss on cash flow hedges

(46)

(59)

(697)

(59)

Total comprehensive income

11,306

16,538

19,245

19,638

Net income attributable to redeemable non-controlling interests

^[1]

9,405

14,183

16,573

16,178

Other comprehensive loss attributable to redeemable non-controlling interests

(68)

(474)

(819)

(44)

Comprehensive income attributable to non-redeemable non-controlling interests

130

329

328

Dividends on redeemable preferred non-controlling interests

438

431

1,313

1,292

Comprehensive income attributable to Class A common stockholders

$ 1,438

$ 2,268

$ 1,849

$ 1,884

[1]

(1) Includes $2,179 and $2,186 of dividends attributable to redeemable non-controlling interests for the three months ended September 30, 2025 and 2024, respectively; includes $6,538 and $6,561 of dividends attributable to redeemable non-controlling interests for the nine months ended September 30, 2025 and 2024, respectively.

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN REDEEMABLE NON-CONTROLLING INTEREST, REDEEMABLE PREFERRED NON-CONTROLLING INTEREST AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Class A Common Stock	Class B Common Stock	Class D Common Stock	Redeemable Preferred non-controlling interests	Redeemable non-controlling interests	Common stock Class A Common Stock	Common stock Class B Common Stock	Common stock Class D Common Stock	Additional Paid-in capital	(Accumulated deficit) Retained Earnings	Accumulated other comprehensive (loss)/income	Non-redeemable non-controlling interests	Treasury Stock Class A Common Stock
Beginning balance (in shares) at Dec. 31, 2023							29,701,146	0	144,399,037
Beginning balance at Dec. 31, 2023	$ (477,852)						$ 3	$ 0	$ 14	$ 0	$ (467,195)	$ (15)	$ 955	$ (11,614)
Treasury stock, beginning balance (in shares) at Dec. 31, 2023														(1,635,783)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	112										110		2
Other comprehensive (loss) income	57											57
Issuance of Class A common stock under the ATM program (in shares)							14,005
Issuance of Class A common stock under the ATM program	97									97
Share conversion (in shares)								71,500,000	(71,500,000)
Share conversion	0							$ 7	$ (7)
Issuance of Class A common stock for vesting of equity awards net of tax withholdings (in shares)							307,137
Issuance of Class A common stock for vesting of equity awards net of tax withholdings	(627)									(627)
Stock-based compensation	165									165
Distributions to non-redeemable non-controlling interests	(233)												(233)
Dividends on redeemable preferred non-controlling interests	(426)										(426)
Change in redemption value of Redeemable non-controlling interests	97,044									365	96,679
Ending balance (in shares) at Mar. 31, 2024							30,022,288	71,500,000	72,899,037
Ending balance at Mar. 31, 2024	(381,663)						$ 3	$ 7	$ 7	0	(370,832)	42	724	$ (11,614)
Treasury stock, ending balance (in shares) at Mar. 31, 2024														(1,635,783)
Beginning balance at Dec. 31, 2023					$ 132,617	$ 802,720
Increase (Decrease) In Temporary Equity And Redeemable Noncontrolling Interest [Abstract]
Net income						565
Other comprehensive income (loss)						293
Stock-based compensation						848
Dividends on redeemable preferred non-controlling interests					2,618
Dividends on redeemable preferred non-controlling interests						(2,192)
Change in redemption value of Redeemable non-controlling interests						(97,044)
Payment of preferred dividend					(5,235)
Ending balance at Mar. 31, 2024					130,000	705,190
Beginning balance (in shares) at Dec. 31, 2023							29,701,146	0	144,399,037
Beginning balance at Dec. 31, 2023	(477,852)						$ 3	$ 0	$ 14	0	(467,195)	(15)	955	$ (11,614)
Treasury stock, beginning balance (in shares) at Dec. 31, 2023														(1,635,783)
Ending balance (in shares) at Sep. 30, 2024							30,065,260	71,500,000	72,899,037
Ending balance at Sep. 30, 2024	(179,495)						$ 3	$ 7	$ 7	0	(168,458)	(25)	585	$ (11,614)
Treasury stock, ending balance (in shares) at Sep. 30, 2024														(1,635,783)
Beginning balance at Dec. 31, 2023					132,617	802,720
Increase (Decrease) In Temporary Equity And Redeemable Noncontrolling Interest [Abstract]
Other comprehensive income (loss)	44
Ending balance at Sep. 30, 2024					130,000	519,373
Beginning balance (in shares) at Mar. 31, 2024							30,022,288	71,500,000	72,899,037
Beginning balance at Mar. 31, 2024	(381,663)						$ 3	$ 7	$ 7	0	(370,832)	42	724	$ (11,614)
Treasury stock, beginning balance (in shares) at Mar. 31, 2024														(1,635,783)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	478										282		196
Other comprehensive (loss) income	28											28
Issuance of Class A common stock under the ATM program (in shares)							22,348
Issuance of Class A common stock under the ATM program	73									73
Issuance of Class A common stock for vesting of equity awards net of tax withholdings (in shares)							13,933
Stock-based compensation	304									304
Distributions to non-redeemable non-controlling interests	(341)									62			(403)
Dividends on redeemable preferred non-controlling interests	(435)										(435)
Change in redemption value of Redeemable non-controlling interests	109,043									(439)	109,482
Ending balance (in shares) at Jun. 30, 2024							30,058,569	71,500,000	72,899,037
Ending balance at Jun. 30, 2024	(272,513)						$ 3	$ 7	$ 7	0	(261,503)	70	517	$ (11,614)
Treasury stock, ending balance (in shares) at Jun. 30, 2024														(1,635,783)
Beginning balance at Mar. 31, 2024					130,000	705,190
Increase (Decrease) In Temporary Equity And Redeemable Noncontrolling Interest [Abstract]
Net income						1,430
Other comprehensive income (loss)						137
Stock-based compensation						1,538
Dividends on redeemable preferred non-controlling interests					2,618
Dividends on redeemable preferred non-controlling interests						(2,183)
Change in redemption value of Redeemable non-controlling interests						(109,043)
Payment of preferred dividend					(2,618)
Ending balance at Jun. 30, 2024					130,000	597,069
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,923										2,793		130
Other comprehensive (loss) income	(95)											(95)
Issuance of Class A common stock for vesting of equity awards net of tax withholdings (in shares)							6,691
Stock-based compensation	240									240
Distributions to non-redeemable non-controlling interests	(55)									7			(62)
Dividends on redeemable preferred non-controlling interests	(431)										(431)
Change in redemption value of Redeemable non-controlling interests	90,436									(247)	90,683
Ending balance (in shares) at Sep. 30, 2024							30,065,260	71,500,000	72,899,037
Ending balance at Sep. 30, 2024	(179,495)						$ 3	$ 7	$ 7	0	(168,458)	(25)	585	$ (11,614)
Treasury stock, ending balance (in shares) at Sep. 30, 2024														(1,635,783)
Increase (Decrease) In Temporary Equity And Redeemable Noncontrolling Interest [Abstract]
Net income						14,183
Other comprehensive income (loss)	474					474
Stock-based compensation						1,217
Dividends on redeemable preferred non-controlling interests					2,617
Dividends on redeemable preferred non-controlling interests						(2,186)
Change in redemption value of Redeemable non-controlling interests						(90,436)
Payment of preferred dividend					(2,617)
Ending balance at Sep. 30, 2024					130,000	519,373
Beginning balance (in shares) at Dec. 31, 2024		28,429,477	71,500,000	72,899,037			30,065,260	71,500,000	72,899,037
Beginning balance at Dec. 31, 2024	$ (147,831)						$ 3	$ 7	$ 7	0	(137,004)	152	618	$ (11,614)
Treasury stock, beginning balance (in shares) at Dec. 31, 2024	(1,635,783)													(1,635,783)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 278										202		76
Other comprehensive (loss) income	(94)											(94)
Issuance of Class A common stock for vesting of equity awards net of tax withholdings (in shares)							542,404
Issuance of Class A common stock for vesting of equity awards net of tax withholdings	(382)									(382)
Stock-based compensation	293									293
Distributions to non-redeemable non-controlling interests	(60)												(60)
Dividends on redeemable preferred non-controlling interests	(437)										(437)
Change in redemption value of Redeemable non-controlling interests	205,959									89	205,870
Ending balance (in shares) at Mar. 31, 2025							30,607,664	71,500,000	72,899,037
Ending balance at Mar. 31, 2025	57,726						$ 3	$ 7	$ 7	0	68,631	58	634	$ (11,614)
Treasury stock, ending balance (in shares) at Mar. 31, 2025														(1,635,783)
Beginning balance at Dec. 31, 2024					130,000	482,863
Increase (Decrease) In Temporary Equity And Redeemable Noncontrolling Interest [Abstract]
Net income						1,006
Other comprehensive income (loss)						(469)
Stock-based compensation						1,458
Dividends on redeemable preferred non-controlling interests					2,617
Dividends on redeemable preferred non-controlling interests						(2,180)
Change in redemption value of Redeemable non-controlling interests						(205,959)
Payment of preferred dividend					(2,617)
Ending balance at Mar. 31, 2025					130,000	276,719
Beginning balance (in shares) at Dec. 31, 2024		28,429,477	71,500,000	72,899,037			30,065,260	71,500,000	72,899,037
Beginning balance at Dec. 31, 2024	$ (147,831)						$ 3	$ 7	$ 7	0	(137,004)	152	618	$ (11,614)
Treasury stock, beginning balance (in shares) at Dec. 31, 2024	(1,635,783)													(1,635,783)
Ending balance (in shares) at Sep. 30, 2025		28,996,177	121,500,000	22,899,037			30,631,960	121,500,000	22,899,037
Ending balance at Sep. 30, 2025	$ 10,268						$ 3	$ 12	$ 2	0	19,089	(12)	2,788	$ (11,614)
Treasury stock, ending balance (in shares) at Sep. 30, 2025	(1,635,783)													(1,635,783)
Beginning balance at Dec. 31, 2024					130,000	482,863
Increase (Decrease) In Temporary Equity And Redeemable Noncontrolling Interest [Abstract]
Other comprehensive income (loss)	$ 819
Payment of preferred dividend					(7,851)
Ending balance at Sep. 30, 2025					130,000	342,528
Beginning balance (in shares) at Mar. 31, 2025							30,607,664	71,500,000	72,899,037
Beginning balance at Mar. 31, 2025	57,726						$ 3	$ 7	$ 7	0	68,631	58	634	$ (11,614)
Treasury stock, beginning balance (in shares) at Mar. 31, 2025														(1,635,783)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,397										1,237		160
Other comprehensive (loss) income	(56)											(56)
Issuance of Class A common stock under the ATM program (in shares)							17,104
Issuance of Class A common stock under the ATM program	58									58
Share conversion (in shares)								50,000,000	(50,000,000)
Share conversion	0							$ 5	$ (5)
Issuance of Class A common stock for vesting of equity awards net of tax withholdings (in shares)							7,192
Issuance of Class A common stock for vesting of equity awards net of tax withholdings	(5)									(5)
Stock-based compensation	369									369
Distributions to non-redeemable non-controlling interests	(50)												(50)
Dividends on redeemable preferred non-controlling interests	(438)										(438)
Capital contribution from non-redeemable non-controlling interests	1,991												1,991
Change in redemption value of Redeemable non-controlling interests	(83,294)									(422)	(82,872)
Ending balance (in shares) at Jun. 30, 2025							30,631,960	121,500,000	22,899,037
Ending balance at Jun. 30, 2025	(22,302)						$ 3	$ 12	$ 2	0	(13,442)	2	2,735	$ (11,614)
Treasury stock, ending balance (in shares) at Jun. 30, 2025														(1,635,783)
Beginning balance at Mar. 31, 2025					130,000	276,719
Increase (Decrease) In Temporary Equity And Redeemable Noncontrolling Interest [Abstract]
Net income						6,162
Other comprehensive income (loss)						(282)
Stock-based compensation						1,835
Dividends on redeemable preferred non-controlling interests					2,617
Dividends on redeemable preferred non-controlling interests						(2,180)
Change in redemption value of Redeemable non-controlling interests						83,294
Payment of preferred dividend					(2,617)
Ending balance at Jun. 30, 2025					130,000	365,548
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,981										1,888	0	93
Other comprehensive (loss) income	(14)											(14)
Stock-based compensation	150									150
Distributions to non-redeemable non-controlling interests	(40)												(40)
Dividends on redeemable preferred non-controlling interests	(438)											(438)
Change in redemption value of Redeemable non-controlling interests	30,931									(150)		31,081
Ending balance (in shares) at Sep. 30, 2025		28,996,177	121,500,000	22,899,037			30,631,960	121,500,000	22,899,037
Ending balance at Sep. 30, 2025	$ 10,268						$ 3	$ 12	$ 2	$ 0	$ 19,089	$ (12)	$ 2,788	$ (11,614)
Treasury stock, ending balance (in shares) at Sep. 30, 2025	(1,635,783)													(1,635,783)
Increase (Decrease) In Temporary Equity And Redeemable Noncontrolling Interest [Abstract]
Net income						9,405
Other comprehensive income (loss)	$ 68					(67)
Stock-based compensation						752
Dividends on redeemable preferred non-controlling interests					2,617
Dividends on redeemable preferred non-controlling interests						(2,179)
Change in redemption value of Redeemable non-controlling interests						(30,931)
Payment of preferred dividend					(2,617)
Ending balance at Sep. 30, 2025					$ 130,000	$ 342,528

Leases (Tables)

9 Months Ended

Sep. 30, 2025

Leases [Abstract]

Schedule of Lessor Contract


	Three months ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
FPAs (1)	$	5,240	$	1,154	$	10,044	$	2,861
PPAs (2)	$	228	$	267	$	875	$	696

(1) Included in Fuel Station Service revenues

(2) Included in Renewable Power revenues

Net Income Per Share (Tables)

9 Months Ended

Sep. 30, 2025

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Income Per Unit

The following table summarizes the calculation of basic and diluted net income per share:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Net income attributable to Class A common stockholders	$	1,450	$	2,362	$	2,015	$	1,893

Weighted average number of shares of Class A common stock - basic	28,279,527		27,709,203		28,090,014		27,585,620
Dilutive effect of stock options and restricted stock units	1,313,295		34,214		923,691		58,544
Weighted average number of shares of Class A common stock - diluted	29,592,822		27,743,417		29,013,705		27,644,164
Net income per share of Class A common stock
Basic	$	0.05	$	0.09	$	0.07	$	0.07
Diluted	$	0.05	$	0.09	$	0.07	$	0.07

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

The following table presents the forms of antidilutive potential common shares:


	Three months ended September 30,		Nine Months Ended September 30,
	2025	2024	2025	2024
Stock options	483,502	507,121	483,502	507,121
Unvested PSUs	1,954,966	2,918,668	1,954,966	2,918,668
Unvested RSUs	1,068,958	1,558,615	1,068,958	1,564,331
OPAL Fuels Class B units	144,399,037	144,399,037	144,399,037	144,399,037

Stock-based compensation

9 Months Ended

Sep. 30, 2025

Share-Based Payment Arrangement [Abstract]

Stock-based compensation

The stock-based compensation expense for the above stock awards under the 2022 Plan as well as Parent Equity Awards is included in the selling, general and administrative expenses:


	Three months ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
2022 Plan	$	902	$	1,457	$	4,729	$	4,043
Parent Equity Awards	—		—		129		269
Total	$	902	$	1,457	$	4,858	$	4,312

Related Parties - Various Balances for Related Parties (Details) - Related Party - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Assets
Accounts receivable, related party	$ 21,691	$ 14,522
Liabilities:
Accounts payable, related party	7,425	7,932
NextEra
Assets
Accounts receivable, related party	21,645	14,522
Liabilities:
Accounts payable, related party	500	501
Equity Method Investment Entities
Assets
Accounts receivable, related party	46	0
Liabilities:
Accounts payable, related party	6,860	6,946
Fortistar and Costar \| Staffing and management services
Liabilities:
Accounts payable, related party	$ 65	$ 485

Redeemable non-controlling interests, Redeemable preferred non-controlling interests and Stockholders' Equity (Deficit) - Changes in Redeemable Preferred Units (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025
Redeemable Preferred non-controlling interests
Increase (Decrease) In Temporary Equity, Amount [Roll Forward]
Beginning balance	$ 130,000	$ 130,000	$ 130,000	$ 130,000	$ 130,000	$ 132,617	$ 130,000
Preferred dividends attributable to Redeemable non-controlling interest							6,538
Preferred dividends attributable to Class A common stockholders							1,313
Payment of preferred dividends	(2,617)	(2,617)	(2,617)	(2,617)	(2,618)	(5,235)	(7,851)
Ending balance	$ 130,000	$ 130,000	$ 130,000	$ 130,000	$ 130,000	$ 130,000	$ 130,000
Series A-1 preferred units
Increase (Decrease) In Temporary Equity, Units [Roll Forward]
Beginning balance (in shares)			300,000				300,000
Preferred dividends attributable to Redeemable non-controlling interest (in shares)							0
Preferred dividends attributable to Class A common stockholders (in shares)							0
Payment of preferred dividends (in shares)							0
Ending balance (in shares)	300,000						300,000
Increase (Decrease) In Temporary Equity, Amount [Roll Forward]
Beginning balance			$ 30,000				$ 30,000
Preferred dividends attributable to Redeemable non-controlling interest							1,509
Preferred dividends attributable to Class A common stockholders							303
Payment of preferred dividends							(1,812)
Ending balance	$ 30,000						$ 30,000
Series A preferred units
Increase (Decrease) In Temporary Equity, Units [Roll Forward]
Beginning balance (in shares)			1,000,000				1,000,000
Preferred dividends attributable to Redeemable non-controlling interest (in shares)							0
Preferred dividends attributable to Class A common stockholders (in shares)							0
Payment of preferred dividends (in shares)							0
Ending balance (in shares)	1,000,000						1,000,000
Increase (Decrease) In Temporary Equity, Amount [Roll Forward]
Beginning balance			$ 100,000				$ 100,000
Preferred dividends attributable to Redeemable non-controlling interest							5,029
Preferred dividends attributable to Class A common stockholders							1,010
Payment of preferred dividends							(6,039)
Ending balance	$ 100,000						$ 100,000

Derivative Financial Instruments and Fair Value Measurements

9 Months Ended

Sep. 30, 2025

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments and Fair Value Measurements

Interest rate swaps

The Company records the fair value of the interest rate swap as an asset or liability on its balance sheet. This instrument is classified as Level 2 in the fair value hierarchy. The effective portion of the swap is recorded in accumulated other comprehensive income. The Company expects to release $84 from the other comprehensive income in the next twelve months.

The location and amounts of interest rate swaps and their fair values in the condensed consolidated balance sheets are:


	September 30, 2025		December 31, 2024		Location of Fair Value Recognized in Balance Sheet
Derivatives designated as cash flow hedges:
Short term portion of the interest rate swaps	$	84	$	238	Prepaid expenses and other current assets
Long term portion of the interest rate swaps	—		448		Other long-term assets
Long term portion of the interest rate swaps	(95)		—		Other long-term liabilities
	$	(11)	$	686

The effect of interest rate swaps on the condensed consolidated statement of operations were as follows:


	Three months ended September 30,				Nine months ended September 30,				Location of Gain in Operations from Derivatives
	2025		2024		2025		2024
Gain on net periodic settlements	$	72	$	—	$	217	$	—	Interest and financing expense, net

Commodity swap contracts

In February 2025, the Company entered into a power purchase and sale agreement with NextEra Energy Marketing, LLC (together with its affiliates, "NextEra") for sale of electricity over the period from March through December 2025, with a fixed contract price. The forward contract is expected to be settled by physical delivery of electricity on a monthly basis. The Company elected the normal purchase normal sale exclusion and will not apply fair value accounting under ASC 815, Derivatives and Hedging, ("ASC 815").

Additionally, during the nine months ended September 30, 2025, the Company entered into multiple ISDA agreements with JPMorgan Chase, Merrill Lynch, and Investec Bank for pay-variable, receive-fixed, cash-settled natural gas commodity swaps. The Company applied fair value accounting under ASC 815 for these transactions.

The following table summarizes the effect of commodity swaps accounted for as derivatives under ASC 815 on the condensed consolidated statements of operations for the three and nine months ended September 30, 2025 and 2024:


		Three months ended September 30,				Nine months ended September 30,
Derivatives not designated as hedging instruments:	Location of Gain (Loss) Recognized	2025		2024		2025		2024
Commodity swaps - realized gain (loss)	Revenues - Renewable Power	$	8	$	200	$	(52)	$	609
Commodity swaps - unrealized gain (loss)	Revenues - Renewable Power	12		(170)		—		(494)
Commodity swaps - realized gain	Revenues - RNG Fuel	1,029		—		1,900		—
Commodity swaps - unrealized gain	Revenues - RNG Fuel	313		—		920		—
Total realized and unrealized gain		$	1,362	$	30	$	2,768	$	115

The following table summarizes the derivative assets and liabilities related to commodity swaps as of September 30, 2025 and December 31, 2024:


	Fair Value
	September 30, 2025		December 31, 2024		Location of Fair Value Recognized in Balance Sheet
Derivatives not designated as hedging instruments
Current portion of unrealized gain on commodity swaps	$	920	$	—	Prepaid expense and other current assets
Current portion of unrealized loss on commodity swaps	(72)		(9)		Accrued expenses and other current liabilities
Non - current portion of unrealized loss on commodity swaps	—		(63)		Other long-term liabilities
Total commodity swaps - unrealized gain (loss)	$	848	$	(72)

Other derivative liabilities

On July 21, 2022, the Company recorded a derivative liability for the Sponsor Earnout Awards and the OPAL Earnout Awards. The OPAL Earnout Awards expired in December 2024. The change in fair value on Sponsor Earnout and OPAL Earnout Awards is recorded as change in fair value of derivative instruments, net in the condensed consolidated statement of operations for the three and nine months ended September 30, 2025 and 2024.

The following table summarizes the effect of change in fair value of other derivative liabilities on the condensed consolidated statements of operations for the three and nine months ended September 30, 2025 and 2024:


Derivative liability	Three months ended September 30,				Nine months ended September 30,				Location of Gain in Operations from Derivatives
	2025		2024		2025		2024
Sponsor Earnout Awards gain	$	—	$	278	281		1,457
	$	—	$	278	$	281	$	1,457	Change in fair value of derivative instruments, net

Fair value measurements

The carrying amount of cash and cash equivalents, accounts receivable, net, and accounts payable and accrued expenses approximates fair value due to their short-term maturities.

The carrying value of the Company's long-term debt, classified as Level 2 within the fair value hierarchy, approximates its fair value as of as of September 30, 2025 and December 31, 2024, because the interest rates are variable and therefore reflect current market conditions.

The Company accounts for asset retirement obligations by recording the fair value of a liability for an asset retirement obligation in the period in which it is incurred and when a reasonable estimate of fair value can be made. The Company estimated the fair value of its asset retirement obligations based on discount rates ranging from 5.8% to 8.5%.

The fair value of the Sponsor Earnout Awards as of September 30, 2025 was determined using a Black-Scholes valuation model with a distribution of potential outcomes on a daily basis over the 2.0 years remaining in the vesting window. Assumptions used in the valuation are as follows:

•Current stock price — The Company's closing stock price of $2.20 as of September 30, 2025;

•Expected volatility —50% based on historical and implied volatilities of selected industry peers deemed to be comparable to our business corresponding to the expected term of the awards;

•Risk-free interest rate — 3.6% based on the U.S. Treasury yield curve in effect at the time of issuance for zero-coupon U.S. Treasury notes with maturities corresponding to the expected 1.8 year term of the earnout period;

•Dividend yield - zero.

Convertible note receivable

In July 2024, the Company purchased a convertible note pursuant to which the Company has the right to convert the note into shares of Class A common stock of the investee for $750. In the third quarter of 2025, the investee underwent an exit event, resulting in the note settlement. The Company received $1,377 in cash proceeds, with an additional $198 remaining in escrow recorded under prepaid expense and other current assets.

There were no transfers of assets between Level 1, Level 2, or Level 3 of the fair value hierarchy as of September 30, 2025.

The Company's assets and liabilities that are measured at fair value on a recurring basis include the following as of September 30, 2025 and December 31, 2024, set forth by level, within the fair value hierarchy:


	Fair value as of September 30, 2025
	Level 1		Level 2		Level 3		Total
Liabilities:
Earnout liabilities	$	—	$	—	$	23	$	23
Interest rate swap contracts	—		95		—		95
Commodity swap contracts	—		72		—		72
Assets:
Cash and cash equivalents and restricted cash - current and non-current (1)	34,283		—		—		34,283
Interest rate swap contracts	—		84		—		84
Commodity swap contracts	—		920		—		920


	Fair value as of December 31, 2024
	Level 1		Level 2		Level 3		Total
Liabilities:
Earnout liabilities	$	—	$	—	$	304	$	304
Commodity swap contracts	—		72		—		72
Assets:
Cash and cash equivalents and restricted cash - current and non-current (1)	29,228		—		—		29,228
Interest rate swap contracts	—		686		—		686
Convertible note receivable	—		—		760		760

(1) Includes balances in money market accounts of $26,213 and $19,786, respectively as of September 30, 2025 and December 31, 2024.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2025

Accounting Policies [Abstract]

Basis of Presentation and Principles of Consolidation

The unaudited condensed consolidated financial statements include the accounts of OPAL Fuels, Inc. and its subsidiaries (the “Company”, “OPAL Fuels”, “we,” “us” or “our”) and reflect all normal recurring adjustments which are, in the opinion of management, necessary for a fair statement of the results of operations for the interim period. In addition, we have consolidated the financial results of jointly owned affiliated companies in which our principal stockholder or other entities have a noncontrolling interest. All intercompany transactions and balances have been eliminated in consolidation. The non-controlling interest attributable to the Company's variable interest entities ("VIE") are presented as a separate component from the Stockholders' equity (deficit) in the condensed consolidated balance sheets and as a non-redeemable non-controlling interest in the condensed consolidated statements of changes in redeemable non-controlling interests, redeemable preferred non-controlling interests and stockholders' equity (deficit).

As of September 30, 2025, the Company held equity interests in twelve VIEs — Pine Bend RNG LLC ("Pine Bend"), Noble Road RNG LLC ("Noble Road"), Paragon RNG LLC ("Paragon"), Emerald RNG LLC ("Emerald") - Paragon project, Sapphire RNG LLC ("Sapphire") - Paragon project, Land2Gas LLC ("Land2Gas"), Atlantic RNG LLC ("Atlantic") - Land2Gas project, Burlington RNG LLC ("Burlington") - Land2Gas project, GREP BTB Holdings LLC ("GREP"), Sunoma Holdings, LLC (“Sunoma”), Central Valley LLC (“Central Valley”), and CMS RNG LLC ("CMS"). Pine Bend, Noble Road GREP, Paragon projects, Land2Gas projects were presented as equity method investments and the remaining three VIEs — Sunoma, Central Valley, and CMS are consolidated by the Company.

On May 9, 2025, the Company acquired a variable interest in CMS, a joint venture formed with a third party to develop, construct, own, and operate a renewable natural gas facility. The Company holds a 70% membership interest in CMS RNG, and the remaining 30% is held by the third-party partner.

Based on an evaluation under ASC 810, Consolidation ("ASC 810"), management determined that CMS RNG is a VIE and that the Company is the primary beneficiary. This conclusion is based on the Company’s power to direct the activities that most significantly impact CMS RNG’s economic performance and its exposure to the entity’s residual returns. As a result, CMS RNG has been consolidated in the Company’s financial statements beginning in the second quarter of 2025.

At the time of formation of CMS RNG, the Company and the third-party partner made net capital contributions of $4,646 and $1,998, respectively. A noncontrolling interest ("NCI") of $1,998 was recognized for the portion of CMS RNG not owned by the Company.

The Company will reassess its primary beneficiary conclusion on an ongoing basis, including upon execution of additional agreements and commencement of commercial operations.

The condensed consolidated balance sheets summarize the major consolidated balance sheet items for consolidated VIEs as of September 30, 2025 and December 31, 2024. The information is presented on an aggregate basis based on similar risk and reward characteristics and the nature of our involvement with the VIEs, such as:

•All of the VIEs are RNG facilities and they are reported under the RNG Fuel Supply segment;

•The nature of our interest in these entities is primarily equity based and therefore carry similar risk and reward characteristics.

The 2024 year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America ("U.S. GAAP"). The interim financial information and notes thereto should be read in conjunction with the Company's latest Annual Report on Form 10-K for the fiscal year ended December 31, 2024 (the "Annual Report") as the interim disclosures generally do not repeat those in the annual financial statements and are condensed in accordance with the instructions to Form 10-Q and Article 10 of Regulation S-X. The results of operations for the three and nine months ended September 30, 2025, are not necessarily indicative of results to be expected for the entire fiscal year.

The Company is organized into three operating segments which are RNG Fuel, Fuel Station Services and Renewable Power.

All amounts in these footnotes are presented in thousands of dollars except share and per share data.

Use of estimates

The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. The significant estimates and assumptions of the Company include the residual value of the useful lives of our property, plant and equipment, the fair value of long-lived assets, the fair value of stock-based compensation, asset retirement obligations, percentage completion for revenue recognition, incremental borrowing rate for calculating the right-of-use lease assets and lease liabilities, the fair value of the reporting units of goodwill and the fair value of derivative instruments. Actual results could differ from those estimates.

The results of operations for the interim periods presented are not necessarily indicative of the results that may be expected for the entire year.

The Company provides all third-party construction contracts with a warranty, typically for a period of one year after substantial completion of the construction project. These warranties are accounted for under ASC 460, Guarantees ("ASC 460"), and not as a separate performance obligation. Generally, the company estimates warranty costs based on historical claims experience, and other factors. Actual warranty claims may differ from the estimates, and adjustments to the liability are made, as necessary. The Company accrued $280 and $171 of warranty reserves under accrued expenses and other current liabilities as of September 30, 2025, and December 31, 2024, respectively.

Accounting Pronouncements Adopted/Accounting Pronouncements Not Yet Adopted

Accounting Pronouncements Adopted

In August 2023, the FASB issued Accounting Standards Update No. 2023-05, Business Combinations- Joint Venture Formations (Subtopic 805-60) ("ASU 2023-05"). The update requires all joint ventures formed after January 1, 2025, upon formation, to apply a new basis of accounting and initially measure its assets and liabilities at fair value. ASU 2023-05 is effective prospectively for joint ventures with a formation date on or after January 1, 2025. During the nine months ended September 30, 2025, the Company formed a joint venture that was excluded from this guidance due to the scope exception applicable to combinations between entities, businesses, or nonprofit activities under common control. The adoption did not have a material effect on the Company’s financial position, results of operations, cash flows or disclosures.

Accounting Pronouncements Not Yet Adopted

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvement to Income Tax Disclosures. The amendments further enhance income tax disclosures, primarily through standardization and disaggregation of rate reconciliation categories and income taxes paid by jurisdiction. The amendments require disclosure of specific categories in the rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold and further disaggregation of income taxes paid for individually significant jurisdictions. The ASU is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently evaluating the impact that this guidance will have on the disclosures and the Company believes the adoption will not have a material effect on our condensed consolidated financial statements.

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, which requires additional, disaggregated disclosure about certain income statement line items. The ASU is effective for fiscal years beginning after December 15, 2026, and is required to be applied prospectively with the option for retrospective application. The Company is currently evaluating the impact that this guidance will have on the disclosures within our condensed consolidated financial statements.

In July 2025, the Financial Accounting Standards Board (“FASB”) issued ASU 2025‑05, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets. The amendments provide a practical expedient applicable to all entities for estimating expected credit losses on current accounts receivable and current contract assets that arise under ASC 606, permitting the assumption that existing conditions at the balance‑sheet date will remain unchanged over the remaining life of such assets. The amendments are effective for fiscal years beginning after December 15, 2025, including interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the impact that this guidance will have on the disclosures within our condensed consolidated financial statements.

In September 2025, the FASB issued ASU 2025‑06, Intangibles — Goodwill and Other (Topic 350): Internal‑Use Software — Targeted Improvements to the Accounting for Internal‑Use Software. The amendments modernize the guidance for capitalizing costs of internally‑developed software by removing references to defined development stages and instead focusing on two principal criteria: (1) management has authorized and committed to funding the project, and (2) it is probable that the project will be completed and the software will be used to perform the intended function. The ASU is effective for fiscal years beginning after December 15, 2027, including interim periods within those years, with early adoption permitted. The Company is currently evaluating the impact that this guidance will have on the disclosures within our condensed consolidated financial statements.

Earnout Liabilities

In connection with the Business Combination completed in July 2022 and pursuant to a sponsor letter agreement, ArcLight CTC Holdings II, L.P. agreed to subject 10% of its Class A common stock (received as a result of the conversion of its ArcLight Class B ordinary shares immediately prior to the closing) to vesting and forfeiture conditions relating to VWAP targets for the Company's Class A common stock sustained over a period of 60 months following the closing. As of September 30, 2025 and December 31, 2024, the number of shares subject to forfeiture was 716,650 (the "Sponsor Earnout Awards").

Redeemable non-controlling interests

Redeemable non-controlling interests represent the portion of the Company's consolidated subsidiary OPAL Fuels LLC, that the Company does not own. The Redeemable non-controlling interest represents 144,399,037 Class B and D Units issued by OPAL Fuels to the prior investors. The Company allocates net income or loss attributable to Redeemable non-controlling interest based on weighted average ownership interest during the period. The net income or loss attributable to Redeemable non-controlling interests is reflected in the condensed consolidated statements of operations.

At each balance sheet date, the mezzanine equity classified Redeemable non-controlling interests is adjusted up to their maximum redemption value if necessary, with an offset in Stockholders' equity (deficit).

Parts Inventory

Parts inventory, also referred to as supplies inventory, consists of shop spare parts inventory and construction site parts inventory. The substantial amount of inventory is identified, tracked and treated as finished goods.

Environmental credits held for sale

For the three months ended September 30, 2025 and 2024, the Company recorded $4,515 and $1,443 as part of Cost of sales - Fuel Station Services in its condensed consolidated statements of operations to adjust environmental credits held for sale to lower of cost and net realizable value. For the nine months ended September 30, 2025 and 2024, the Company recorded $15,055 and $8,293 as part of Cost of sales - Fuel Station Services in its condensed consolidated statements of operations to adjust environmental credits held for sale to lower of cost and net realizable value.

Investment Tax Credits

In the first, second, and third quarters of 2025, the Company sold to third-party purchasers certain transferable Investment Tax Credits ("ITCs") that had been generated by the Company from its investments in the Renewable Natural Gas segment.

The Company elected to consider expected transfers of the credits in assessing their realizability as part of the valuation allowance analysis and recognize changes in the estimated proceeds as an adjustment to its valuation allowance. The Company accounted for the ITC sale in accordance with ASC 740, Income Taxes ("ASC 740"), by electing the flow-through method to recognize the ITC benefit when it arises.

Leases

Lessor contracts

Fuel provider agreements

Fuel provider agreements ("FPAs") are for the sale of brown gas, service and maintenance of sites. The Company is contracted to design and build a Fueling Station on the customer's property in exchange for the Company providing CNG/RNG to the customer for a determined number of years. We have determined that the FPAs contain a lease component for the use of the Fueling Station in addition to the non-lease components related to providing CNG/RNG as well as providing all-inclusive maintenance and warranty services.

Power purchase agreements

Power purchase agreements ("PPAs") are for the sale of electricity generated at our Renewable Power facilities. All of our Renewable Power facilities operate under fixed pricing or indexed pricing based on market prices. Two of our Renewable Power facilities transfer the right to control the use of the power plant to the purchaser and are therefore classified as operating leases.


	Three months ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
FPAs (1)	$	5,240	$	1,154	$	10,044	$	2,861
PPAs (2)	$	228	$	267	$	875	$	696

(1) Included in Fuel Station Service revenues

(2) Included in Renewable Power revenues

Lessee contracts

During the nine months ended September 30, 2025, the Company derecognized the right-of-use (ROU) asset and corresponding lease liability associated with a site lease following a formal release from all future lease obligations by the vendor under the current agreement. The ROU asset had a carrying value of approximately $5,397 at the time of termination. The derecognition resulted in $600 gain recognized in other income.

Leases

Lessor contracts

Fuel provider agreements

Power purchase agreements


	Three months ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
FPAs (1)	$	5,240	$	1,154	$	10,044	$	2,861
PPAs (2)	$	228	$	267	$	875	$	696

(1) Included in Fuel Station Service revenues

(2) Included in Renewable Power revenues

Lessee contracts

Fair value measurements

The carrying amount of cash and cash equivalents, accounts receivable, net, and accounts payable and accrued expenses approximates fair value due to their short-term maturities.

Borrowings - Borrowings under Various Debt Facilities (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Non-current borrowings total	$ 330,395	$ 285,003
OPAL Term Loan and Revolving Loan \| OPAL Term Loan and Revolving Loan
Debt Instrument [Line Items]
Long-term debt, gross	331,618	286,617
Less: unamortized debt issuance costs	(8,945)	(9,122)
Less: current portion	(9,349)	(10,865)
Non-current borrowings total	313,324	266,630
Sunoma Loan \| Sunoma Loan
Debt Instrument [Line Items]
Long-term debt, gross	19,539	20,846
Less: unamortized debt issuance costs	(607)	(717)
Less: current portion	(1,861)	(1,756)
Non-current borrowings total	$ 17,071	$ 18,373

- 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 815
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-Name Accounting Standards Codification
-Section 50
-Paragraph 8A
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 7: http://www.xbrl.org/2003/role/exampleRef
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Reference 14: 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 29: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2025

Accounting Policies [Abstract]

Schedule of Disaggregation of Revenue By Product Line

The following table shows the disaggregation of revenue according to product line:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Electricity sales	$	6,456	$	7,011	$	18,349	$	19,663
Third party construction	14,202		10,358		31,377		29,853
Service and parts	6,926		6,512		20,726		18,097
Brown gas sales	8,193		7,987		25,172		19,357
Environmental credits (1)	41,567		50,483		141,431		128,530
Other (2)	545		275		1,246		892
Total revenue from contracts with customers	77,889		82,626		238,301		216,392
Lease revenue (3)	5,468		1,421		10,919		3,557
Total revenue	$	83,357	$	84,047	$	249,220	$	219,949

(1) Includes revenues of $0 and $5,151 respectively, for the three months ended September 30, 2025 and 2024, from customers domiciled outside of United States. Includes revenues of $0 and $13,439 respectively, for the nine months ended September 30, 2025 and 2024, from customers domiciled outside of United States.

(2) Includes management fee revenues earned from management of operations of equity method entities.

(3) Lease revenue relates to revenue from fuel purchasing agreements and power purchase agreements where we determined that we transferred the right to control the use of the power plant to the purchaser.

Schedule of Receivables, Contract Assets and Contract Liabilities From Contracts With Customers

The following table provides information about receivables, contract assets, and contract liabilities from contracts with customers:


	September 30, 2025		December 31, 2024
Accounts receivable, net	$	31,113	$	32,013
Contract assets:
Cost and estimated earnings in excess of billings	11,171		8,547
Accounts receivable retainage, net	1,475		2,528
Contract assets total	12,646		11,075
Contract liabilities:
Billings in excess of costs and estimated earnings	8,378		9,276
Contract liabilities total	$	8,378	$	9,276

Net Income Per Share - Narrative (Details) - shares	3 Months Ended	9 Months Ended
Net Income Per Share - Narrative (Details) - shares	Sep. 30, 2025	Sep. 30, 2025
Earnout Target
Class of Warrant or Right [Line Items]
Antidilutive shares (in shares)	716,650	716,650
Treasury Stock, Common
Class of Warrant or Right [Line Items]
Antidilutive shares (in shares)	1,635,783	1,635,783

Leases - Schedule of Lessor Contract (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Operating Leased Assets [Line Items]
Total revenues	$ 83,357	$ 84,047	$ 249,220	$ 219,949
Fuel Station Services
Operating Leased Assets [Line Items]
Total revenues	51,722	45,395	149,426	121,794
Fuel Station Services \| Fuel Provider Agreements
Operating Leased Assets [Line Items]
Total revenues	5,240	1,154	10,044	2,861
Renewable Power
Operating Leased Assets [Line Items]
Total revenues	8,714	12,788	24,144	35,119
Renewable Power \| Power Purchase Agreements
Operating Leased Assets [Line Items]
Total revenues	$ 228	$ 267	$ 875	$ 696

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Derivative Financial Instruments and Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2025

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Interest Rate Swaps

The location and amounts of interest rate swaps and their fair values in the condensed consolidated balance sheets are:


	September 30, 2025		December 31, 2024		Location of Fair Value Recognized in Balance Sheet
Derivatives designated as cash flow hedges:
Short term portion of the interest rate swaps	$	84	$	238	Prepaid expenses and other current assets
Long term portion of the interest rate swaps	—		448		Other long-term assets
Long term portion of the interest rate swaps	(95)		—		Other long-term liabilities
	$	(11)	$	686

Schedule of Effect of Derivative Instruments on Statement of Operations

The effect of interest rate swaps on the condensed consolidated statement of operations were as follows:


	Three months ended September 30,				Nine months ended September 30,				Location of Gain in Operations from Derivatives
	2025		2024		2025		2024
Gain on net periodic settlements	$	72	$	—	$	217	$	—	Interest and financing expense, net


		Three months ended September 30,				Nine months ended September 30,
Derivatives not designated as hedging instruments:	Location of Gain (Loss) Recognized	2025		2024		2025		2024
Commodity swaps - realized gain (loss)	Revenues - Renewable Power	$	8	$	200	$	(52)	$	609
Commodity swaps - unrealized gain (loss)	Revenues - Renewable Power	12		(170)		—		(494)
Commodity swaps - realized gain	Revenues - RNG Fuel	1,029		—		1,900		—
Commodity swaps - unrealized gain	Revenues - RNG Fuel	313		—		920		—
Total realized and unrealized gain		$	1,362	$	30	$	2,768	$	115

Schedule of Derivatives Fair Values on Balance Sheet

The following table summarizes the derivative assets and liabilities related to commodity swaps as of September 30, 2025 and December 31, 2024:


	Fair Value
	September 30, 2025		December 31, 2024		Location of Fair Value Recognized in Balance Sheet
Derivatives not designated as hedging instruments
Current portion of unrealized gain on commodity swaps	$	920	$	—	Prepaid expense and other current assets
Current portion of unrealized loss on commodity swaps	(72)		(9)		Accrued expenses and other current liabilities
Non - current portion of unrealized loss on commodity swaps	—		(63)		Other long-term liabilities
Total commodity swaps - unrealized gain (loss)	$	848	$	(72)

Schedule of Commodity Swaps And Other Derivatives


Derivative liability	Three months ended September 30,				Nine months ended September 30,				Location of Gain in Operations from Derivatives
	2025		2024		2025		2024
Sponsor Earnout Awards gain	$	—	$	278	281		1,457
	$	—	$	278	$	281	$	1,457	Change in fair value of derivative instruments, net

Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis


	Fair value as of September 30, 2025
	Level 1		Level 2		Level 3		Total
Liabilities:
Earnout liabilities	$	—	$	—	$	23	$	23
Interest rate swap contracts	—		95		—		95
Commodity swap contracts	—		72		—		72
Assets:
Cash and cash equivalents and restricted cash - current and non-current (1)	34,283		—		—		34,283
Interest rate swap contracts	—		84		—		84
Commodity swap contracts	—		920		—		920


	Fair value as of December 31, 2024
	Level 1		Level 2		Level 3		Total
Liabilities:
Earnout liabilities	$	—	$	—	$	304	$	304
Commodity swap contracts	—		72		—		72
Assets:
Cash and cash equivalents and restricted cash - current and non-current (1)	29,228		—		—		29,228
Interest rate swap contracts	—		686		—		686
Convertible note receivable	—		—		760		760

(1) Includes balances in money market accounts of $26,213 and $19,786, respectively as of September 30, 2025 and December 31, 2024.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2025

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

Letters of Credit

As of September 30, 2025 and December 31, 2024, the Company was required to maintain standby letters of credit totaling $15,485 and $15,120, respectively, to support obligations of certain Company's subsidiaries. These letters of credit were issued in favor of a lender, utilities, a governmental agency, and an independent system operator under PPA electrical interconnection agreements, and in place of a debt service reserve. There have been no draws to date on these letters of credit.

Lease commitments

The table below provides the total amount of lease payments on an undiscounted basis on our lease contracts as of September 30, 2025:


	Site leases		Office leases		Vehicle and Equipment leases		Total

Three months ending December 31, 2025	$	261	$	141	$	403	$	805
2026	1,044		47		1,529		2,620
2027	1,094		—		1,035		2,129
2028	1,129		—		347		1,476
2029	1,129		—		—		1,129
2030	1,129		—		—		1,129
Thereafter	18,267		—		—		18,267
	$24,053		$188		$3,314		$27,555

Guaranty

On September 13, 2024, OPAL Paragon, an equity method investment of the Company, entered into a tax credit purchase agreement with Apollo Management Holdings, L.P., ("Buyer"), pursuant to which OPAL Paragon sold $11,096 of investment tax credits to the Buyer for net proceeds of $8,906. If the tax credits are disallowed or recaptured by the government from the Buyer, OPAL Paragon will be required to return the purchase price and pay any taxes, interests or penalties incurred.

In connection with the above transaction, all of the obligations of OPAL Paragon under such tax credit purchase agreement are guaranteed by the Company.

On March 28, 2025, OPAL Paragon entered into a tax credit purchase agreement with the Buyer, pursuant to which OPAL Paragon sold $9,801 of investment tax credits to the Buyer for net proceeds of $8,037. If the tax credits are disallowed or recaptured from the Buyer, OPAL Paragon will be required to return the purchase price and pay any taxes, interests or penalties incurred.

In connection with the above transaction, all of the obligations of OPAL Paragon under such tax credit purchase agreement are guaranteed by the Company.

On June 20, 2025, OPAL Fuels LLC entered into tax credit purchase agreements with the Buyer and EagleBank, pursuant to which OPAL Fuels LLC sold $16,740 of investment tax credits for net proceeds of $13,686. If the tax credits are disallowed or recaptured from the Buyer, OPAL Fuels LLC will be required to return the purchase price and pay any taxes, interests or penalties incurred.

In connection with the above transaction, all of the obligations of OPAL Fuels LLC under such tax credit purchase agreements are guaranteed by the Company.

On September 12, 2025, OPAL Fuels LLC entered into tax credit purchase agreements with the Buyer and Athene Annuity and Life Company, pursuant to which OPAL Fuels LLC sold $17,369 of investment tax credits for net proceeds of $14,567. If the tax credits are disallowed or recaptured from the Buyer, OPAL Fuels LLC will be required to return the purchase price and pay any taxes, interests or penalties incurred.

In connection with the above transaction, all of the obligations of OPAL Fuels LLC under such tax credit purchase agreements are guaranteed by the Company.

Legal Matters

The Company is involved in various claims arising in the normal course of business. Management believes that the outcome of these claims will not have a material adverse effect on the Company's financial position, results of operations or cash flows.

Set forth below is information related to the Company’s material pending legal proceedings as of the date of this report, other than ordinary routine litigation incidental to the business. There have been no material changes to such legal proceedings from the previous quarter.

Central Valley Project

In September 2021, an indirect subsidiary of the Company, MD Digester, LLC (“MD”), entered into a fixed-price Engineering, Procurement and Construction Contract (an “EPC Contract”) with VEC Partners, Inc. d/b/a CEI Builders (“CEI”) for the design and construction of a turn-key renewable natural gas production facility using dairy cow manure as feedstock in California’s Central Valley. In December 2021, a second indirect subsidiary of the Company, VS Digester, LLC (“VS”) entered into a nearly identical EPC Contract (collectively, the "EPC Contracts") with CEI for the design and construction of a second facility, also in California’s Central Valley. CEI’s performance under both of the EPC Contracts is fully bonded by licensed sureties.

CEI submitted a series of change order requests seeking to increase the EPC Contract Price by approximately $14 million, per project, primarily due to: (1) modifications to CEI’s design drawings which are required to meet its contracted performance guaranties, and (2) a default by one of CEI’s major equipment manufacturers. The Company disputes the vast majority of the change order requests.

In January 2024, the Company filed a civil lawsuit captioned, MD Digester, LLC. et. al. vs. VEC Partners, Inc. et. al.; with the California Superior Court, County of San Joaquin; Action No. STK- CV-UCC-2024-0000185 and commenced a related arbitration proceeding in order to obtain a formal determination on the claims; AAA Case No. 01-24-0000-0775. The Superior Court Action has been stayed, pending the conclusion of the arbitration. In the meantime, the AAA has empaneled three experienced arbitrators and has set the hearing date for the matter, currently schedule in May 2026.

The EPC Agreement requires that CEI, continue working during the course of the litigation and related arbitration proceedings; however, CEI effectively stopped working. Between May and August 2024, MD issued a series of Notices of Default and Demands to Cure to CEI. CEI failed to cure, and on July 30, 2024, MD terminated CEI for default. MD notified CEI’s performance bond surety, Atlantic Specialty Insurance Company of the termination and demanded that it perform under the bond. Atlantic has denied the claim.

On July 11, 2024, VS issued a Notice of Default and Demand to Cure, advising CEI of its defaults and giving it an opportunity to cure. CEI failed to do so, and on August 27, 2024, VS terminated CEI for default. VS has notified CEI’s bond surety, also Atlantic, of the second termination and demanded that it perform under the performance bond. The surety has denied the claim.

As a result of CEI’s default and Atlantic’s denial of the claims, MD and VS have amended their claims in the AAA arbitration to include breach of contract claims against CEI and breach of performance bond and payment bond claims against Atlantic (who was formally joined into the arbitration on November 20, 2024) in the AAA Arbitration with CEI.

CEI has since recorded mechanic’s liens against each of the projects for $4,900 (MD) and $2,000 (VS), and filed actions with the Stanislaus and San Joaquin County Superior Courts, respectively, to enforce their liens. MD and VS have since recorded bonds releasing the properties from the liens and it is expected that these claims will be stayed and consolidated with the pending arbitration proceeding.

In addition to the above-referenced action and arbitration, several of CEI’s subcontractors have recorded mechanic’s liens against the MD and VS projects for $3,141, which the Company is obligated to defend and indemnify the dairy owners from and against. Several liens were untimely and have been released.

The Company believes its claims against CEI (and the surety where bond claims are denied) have substantial merit, and intends to prosecute the claims vigorously. However, due to the incipient stage of the litigation and related arbitration, the recency of the termination, and the ongoing status of the proceedings and discussions with the bond surety, as well as the uncertainties involved in all litigation and arbitration, the Company is unable at this time to assess the likely outcome of the litigation and related arbitration, the timing of its resolution, or its ultimate impact, if any, on the Central Valley projects or the Company's business, financial condition or results of operations.

Former Development Partner/Construction Manager

In March 2024, the Company filed an action in the Orange County Superior Court (Case No. 30- 2024-01415510-CU-BC-CXC) against its former development partner and construction manager, Sierra Renewable Organics Management, LLC, as well as its principal (Ethan Werner) and affiliated engineering firm (CH Four Biogas) for Breach of Contract, Indemnity, Declaratory Relief, Intentional Misrepresentation and Negligent Misrepresentation relating to the design and development of the Projects. The defendants have recently filed an answer and certain cross claims, to which the Company has demurred. Discovery in the case is now underway.

Derivative Financial Instruments and Fair Value Measurements - Other Derivative Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Other Derivatives
Derivative [Line Items]
Change in fair value of derivative instruments, net	$ 0	$ 278	$ 281	$ 1,457
Sponsor Earnout Awards gain
Derivative [Line Items]
Change in fair value of derivative instruments, net	$ 0	$ 278	$ 281	$ 1,457

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2025

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation and Principles of Consolidation

The Company will reassess its primary beneficiary conclusion on an ongoing basis, including upon execution of additional agreements and commencement of commercial operations.

•All of the VIEs are RNG facilities and they are reported under the RNG Fuel Supply segment;

•The nature of our interest in these entities is primarily equity based and therefore carry similar risk and reward characteristics.

The Company is organized into three operating segments which are RNG Fuel, Fuel Station Services and Renewable Power.

All amounts in these footnotes are presented in thousands of dollars except share and per share data.

Use of estimates

The results of operations for the interim periods presented are not necessarily indicative of the results that may be expected for the entire year.

Related Party Revenues

The Company revised its disclosure of Fuel Station Services revenues from related parties included parenthetically on the face of the condensed consolidated statements of operations to include amounts that were previously excluded. The amounts are immaterial and the revision had no impact on previously reported net income, cash flows, or financial position.

Accounting Pronouncements Adopted

Accounting Pronouncements Not Yet Adopted

Earnout Liabilities

For the three and nine months ended September 30, 2025 the Company recorded a gain from the Sponsor Earnout Awards of $— and $281, respectively, in its condensed consolidated statements of operations. For the three and nine months ended September 30, 2024, the Company recorded a gain of $278 and $1,457, respectively, in its condensed consolidated statements of operations. As of September 30, 2025 and December 31, 2024, the Company recorded a Sponsor Earnout liability of $23 and $304, respectively, as part of other long-term liabilities on its condensed consolidated balance sheets.

Redeemable non-controlling interests

Parts Inventory

Revenues

Disaggregation of Revenue

The following table shows the disaggregation of revenue according to product line:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Electricity sales	$	6,456	$	7,011	$	18,349	$	19,663
Third party construction	14,202		10,358		31,377		29,853
Service and parts	6,926		6,512		20,726		18,097
Brown gas sales	8,193		7,987		25,172		19,357
Environmental credits (1)	41,567		50,483		141,431		128,530
Other (2)	545		275		1,246		892
Total revenue from contracts with customers	77,889		82,626		238,301		216,392
Lease revenue (3)	5,468		1,421		10,919		3,557
Total revenue	$	83,357	$	84,047	$	249,220	$	219,949

(2) Includes management fee revenues earned from management of operations of equity method entities.

For the three and nine months ended September 30, 2025 and 2024, the third party construction revenue was recognized over time, and the remainder was for products and services transferred at a point in time.

Contract Balances

The following table provides information about receivables, contract assets, and contract liabilities from contracts with customers:


	September 30, 2025		December 31, 2024
Accounts receivable, net	$	31,113	$	32,013
Contract assets:
Cost and estimated earnings in excess of billings	11,171		8,547
Accounts receivable retainage, net	1,475		2,528
Contract assets total	12,646		11,075
Contract liabilities:
Billings in excess of costs and estimated earnings	8,378		9,276
Contract liabilities total	$	8,378	$	9,276

During the nine months ended September 30, 2025, the Company recognized revenue of $5,006 that was included in "Contract liabilities" at December 31, 2024. During the nine months ended September 30, 2024, the Company recognized revenue of $3,746 that was included in "Contract liabilities" at December 31, 2023.

Environmental credits held for sale

Fuel Station Services Construction Backlog

The Company's remaining performance obligations ("Backlog") represent the unrecognized revenue value of its contract commitments. The Company's Backlog may significantly vary each reporting period based on the timing of major new contract commitments. At September 30, 2025, the Company had a Backlog of $51,484.

Significant Customers, Vendors and Concentration of Credit Risk

For the three and nine months ended September 30, 2025, one customer accounted for 34% and 38%, respectively, of the revenue. For the three and nine months ended September 30, 2024, two customers accounted for 56% and 54% of the revenue, respectively. At September 30, 2025, two customers accounted for 55% of accounts receivable. At December 31, 2024, two customers accounted for 50% of accounts receivable.

As of September 30, 2025, one vendor accounted for 10% of the accounts payable. As of December 31, 2024, one vendor accounted for 17% of the accounts payable. Vendor concentration percentages are calculated excluding statutory obligations to government authorities.

Investment Tax Credits

During the three and nine months ended September 30, 2025, the Company received net proceeds from the sale of tax credits totaling $14,567 and $36,290, respectively. During the three and nine months ended September 30, 2024, the Company received net proceeds from the sale of tax credits totaling $8,906. These amounts were received in cash and recorded as income tax benefit. The cash flows related to the total income tax benefits are presented in the statement of cash flow in the ‘Net income’ line item within operating activities. Additionally, during the three and nine months ended September 30, 2025, the Company incurred legal and insurance fees associated with the transactions totaling $1,873 and $4,510, respectively. During the three and nine months ended September 30, 2024, the Company incurred legal and insurance fees associated with the transactions totaling $1,182. These amounts represent buyer’s expenses paid by the Company and are recorded as part of the income tax benefit. The transaction costs are deductible for income tax purposes.

Related Parties - Fees Upon Entering Into Management Services Agreement with Related Party (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Related Party Transaction [Line Items]
Selling, general, and administrative	$ 14,376	$ 12,692	$ 47,803	$ 39,552
Related Party \| Costar
Related Party Transaction [Line Items]
Selling, general, and administrative	1,326	1,530	4,815	4,373
Related Party \| Costar \| Staffing and management services
Related Party Transaction [Line Items]
Selling, general, and administrative	447	535	1,557	1,531
Related Party \| Costar \| Rent - fixed compensation
Related Party Transaction [Line Items]
Selling, general, and administrative	187	181	535	524
Related Party \| Costar \| IT services
Related Party Transaction [Line Items]
Selling, general, and administrative	$ 692	$ 814	$ 2,723	$ 2,318

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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-3

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-13

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: 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/1943274/2147479134/946-220-S99-1

+ Details

- Definition

The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

+ References + Details

Reportable Segments and Geographic Information - Revenue by Major Customer by Reporting Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenue, Major Customer [Line Items]
Revenue	$ 83,357	$ 84,047	$ 249,220	$ 219,949
RNG Fuel
Revenue, Major Customer [Line Items]
Revenue	22,921	25,864	75,650	63,036
Fuel Station Services
Revenue, Major Customer [Line Items]
Revenue	51,722	45,395	149,426	121,794
Renewable Power
Revenue, Major Customer [Line Items]
Revenue	8,714	12,788	24,144	35,119
Customer A
Revenue, Major Customer [Line Items]
Revenue	$ 29,045	$ 35,213	$ 94,987	$ 87,188
Customer A \| Revenue Benchmark \| Customer Concentration Risk
Revenue, Major Customer [Line Items]
Percentage of total revenue	34.00%	42.00%	38.00%	40.00%
Customer A \| RNG Fuel
Revenue, Major Customer [Line Items]
Revenue	$ 17,825	$ 22,798	$ 55,658	$ 54,174
Customer A \| RNG Fuel \| Revenue Benchmark \| Customer Concentration Risk
Revenue, Major Customer [Line Items]
Percentage of total revenue	21.00%	27.00%	22.00%	25.00%
Customer A \| Fuel Station Services
Revenue, Major Customer [Line Items]
Revenue	$ 9,198	$ 10,616	$ 34,653	$ 27,885
Customer A \| Fuel Station Services \| Revenue Benchmark \| Customer Concentration Risk
Revenue, Major Customer [Line Items]
Percentage of total revenue	11.00%	13.00%	14.00%	13.00%
Customer A \| Renewable Power
Revenue, Major Customer [Line Items]
Revenue	$ 2,022	$ 1,799	$ 4,676	$ 5,129
Customer A \| Renewable Power \| Revenue Benchmark \| Customer Concentration Risk
Revenue, Major Customer [Line Items]
Percentage of total revenue	2.00%	2.00%	2.00%	2.00%
Customer B \| Fuel Station Services
Revenue, Major Customer [Line Items]
Revenue		$ 11,503		$ 31,880
Customer B \| Fuel Station Services \| Revenue Benchmark \| Customer Concentration Risk
Revenue, Major Customer [Line Items]
Percentage of total revenue		14.00%		14.00%

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2025
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Investment in Other Entities - Net Income (Loss) From Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Schedule of Equity Method Investments [Line Items]
Revenue	$ 83,357	$ 84,047	$ 249,220	$ 219,949
Net income	11,386	17,107	20,229	19,692
Net income from equity method investments	637	3,822	1,877	11,828
Current assets	122,785		122,785		$ 117,188
Total assets	916,749		916,749		881,077
Current liabilities	83,461		83,461		103,596
Total liabilities	433,953		433,953		416,045
Equity Method Investment
Schedule of Equity Method Investments [Line Items]
Revenue	26,570	26,123	80,844	77,097
Gross profit	6,785	10,799	21,167	31,812
Net income	2,508	$ 7,182	8,791	$ 26,579
Current assets	8,662		8,662		10,554
Noncurrent assets	136,295		136,295		121,934
Total assets	144,957		144,957		132,488
Current liabilities	11,121		11,121		15,993
Noncurrent liabilities	33,991		33,991		24,612
Total liabilities	$ 45,112		$ 45,112		$ 40,605

Borrowings

9 Months Ended

Sep. 30, 2025

Debt Disclosure [Abstract]

Borrowings

The following table summarizes the borrowings under the various debt facilities as of September 30, 2025 and December 31, 2024:


	September 30, 2025		December 31, 2024
OPAL Term Loan and Revolving Loan	$	331,618	$	286,617
Less: unamortized debt issuance costs	(8,945)		(9,122)
Less: current portion	(9,349)		(10,865)
OPAL Term Loan and Revolving Loan, net of debt issuance costs	313,324		266,630
Sunoma Loan	19,539		20,846
Less: unamortized debt issuance costs	(607)		(717)
Less: current portion	(1,861)		(1,756)
Sunoma Loan, net of debt issuance costs	17,071		18,373
Non-current borrowings total	$	330,395	$	285,003

As of September 30, 2025, principal maturities of debt are expected as follows, excluding any undrawn debt facilities as of the date of the condensed consolidated balance sheets:


	OPAL Term Loan		Sunoma Loan		Total
Fiscal year:
Three months ending December 31, 2025	$	—	$	449	$	449
2026	12,465		1,898		14,363
2027	12,465		2,051		14,516
2028	306,688		2,213		308,901
2029	—		2,395		2,395
2030	—		2,589		2,589
Thereafter	—		7,944		7,944
	$	331,618	$	19,539	$	351,157

Amended OPAL Term Loan and Revolving Loan

On March 3, 2025, OPAL Fuels Intermediate HoldCo LLC, as the borrower (the “Borrower”), certain subsidiaries of the Borrower, as guarantors (the “Guarantors”), the lenders and issuers of letters of credit party thereto and Bank of America, N.A. as the administrative agent (the “Administrative Agent”) entered into that certain Amendment No. 1 to Credit and Guarantee Agreement (the “Credit Agreement Amendment”), with respect to that certain Credit and Guarantee Agreement (the “Credit Agreement”) dated September 1, 2023, by and among the Borrower, the Administrative Agent, the financial institutions from time to time parties thereto as lenders and as issuers of letters of credit, and the other agents and persons from time to time party thereto (as amended, restated, amended and restated, supplemented or otherwise modified and in effect from time to time).

The Credit Agreement Amendment makes certain changes to the applicability of certain financial covenants and modifies other covenants to clarify the use of loan proceeds. Additionally, the Credit Agreement Amendment permits the organizational restructuring of the Guarantors in a manner designed to facilitate the sale of federal investment tax credits and the ability to raise additional future capital.

The Credit Agreement Amendment also eases the conditions precedent to making new Projects eligible for borrowing under the Credit Agreement, extends the availability period for delay draw term loans under the Credit Agreement through March 5, 2026, and extends the commencement of repayment of such term loans until March 31, 2026. The Amendment was accounted for as a modification in the nine month period ended September 30, 2025.

In connection with the Credit Agreement Amendment, the Borrower paid the Administrative Agent, for the account of each lender, a one-time nonrefundable fee of $1,250. These costs have been recorded as a direct reduction against the debt and amortized over the life of the associated debt as a component of interest expense using the effective interest method.

During the nine months ended September 30, 2025, the Company borrowed $40,000 under its term loan, drew $20,000 from its revolving loan and repaid $15,000 on its revolving loan. As of September 30, 2025, the Company utilized $34,517 of availability under the revolver loan to provide for the issuance of letters of credit to support the operations of the Borrower and the Guarantors.

The Company has the ability, during the delayed draw availability period and subject to the satisfaction of certain credit and project-related conditions precedent, to join other newly acquired subsidiaries with comparable renewable projects in development under the credit facility for comparable funding. As of September 30, 2025, the Company is in compliance with the financial covenants under the OPAL Term Loan. The amounts outstanding under the Credit Agreement are secured by the assets of the indirect subsidiaries of OPAL Intermediate Holdco.

Sunoma Loan

On August 27, 2020, Sunoma, an indirect wholly-owned subsidiary of the Company entered into a debt agreement (the "Sunoma Loan Agreement") with Live Oak Banking Company for an aggregate principal amount of $20,000 that was increased to $23,000 in 2022. As of September 30, 2025, Sunoma is in compliance with the financial covenants under the Sunoma Loan Agreement.

The Company also utilized $968 for the issuance of letters of credit to support the operations of the Borrower. The amounts outstanding under the Sunoma Loan are secured by the assets of Sunoma.

2025

For the three and nine months ended September 30, 2025, the weighted average effective interest rate including amortization of debt issuance costs on OPAL Term Loan was 8.8% and 8.5% respectively. For the three and nine months ended September 30, 2025, the interest rate on the Sunoma Loan was 8.7%.

2024

For the three and nine months ended September 30, 2024, the weighted average effective interest rate on OPAL Term Loan including amortization of debt issuance costs was 9.2% and 8.7%, respectively. For the three and nine months ended September 30, 2024, the interest rate on the Sunoma loan was 8.1% and 8.2%, respectively.

The following table summarizes the Company's total interest expense for the three and nine months ended September 30, 2025 and 2024:


	Three Months Ended September 30, 2025				Nine Months Ended September 30,
	2025		2024		2025		2024
Sunoma Loan	$	420	$	429	$	1,228	$	1,330
OPAL Term Loan (1)	5,568		4,023		15,879		10,341
Commitment fees and other finance fees	449		667		1,405		2,141
Amortization of deferred financing cost	722		191		1,524		1,310
Interest expense on finance leases	25		144		235		432
Interest income	(286)		(428)		(941)		(1,578)
Total interest and financing expense	$	6,898	$	5,026	$	19,330	$	13,976

- 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 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/470/tableOfContent

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482925/835-30-45-2

Reference 14: 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 15: 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 16: 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 17: 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 18: 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 19: 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 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1E

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1I

Reference 22: 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 23: 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

Investment in Other Entities - Equity Method Investments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Increase (Decrease) In Equity Method Investments [Roll Forward]
Beginning balance	$ 223,594
Income (loss) from equity method investments	7,034
Contribution by the Company	15,300
Distributions from return on investment in equity method investment	(8,059)	$ (13,661)
Distributions from return of investment in equity method investment	(6,236)	$ (1,756)
Other comprehensive (loss)	(287)
Amortization of basis difference	(5,157)
Capitalized interest	1,356
Ending balance	$ 227,545
Pine Bend
Schedule of Equity Method Investments [Line Items]
Percentage of ownership	50.00%
Increase (Decrease) In Equity Method Investments [Roll Forward]
Beginning balance	$ 19,536
Income (loss) from equity method investments	2,354
Contribution by the Company	0
Distributions from return on investment in equity method investment	(1,625)
Distributions from return of investment in equity method investment	0
Other comprehensive (loss)	0
Amortization of basis difference	(118)
Capitalized interest	0
Ending balance	$ 20,147
Noble Road
Schedule of Equity Method Investments [Line Items]
Percentage of ownership	50.00%
Increase (Decrease) In Equity Method Investments [Roll Forward]
Beginning balance	$ 21,097
Income (loss) from equity method investments	2,892
Contribution by the Company	0
Distributions from return on investment in equity method investment	(2,575)
Distributions from return of investment in equity method investment	0
Other comprehensive (loss)	0
Amortization of basis difference	(444)
Capitalized interest	0
Ending balance	$ 20,970
GREP
Schedule of Equity Method Investments [Line Items]
Percentage of ownership	20.00%
Increase (Decrease) In Equity Method Investments [Roll Forward]
Beginning balance	$ 1,760
Income (loss) from equity method investments	(660)
Contribution by the Company	0
Distributions from return on investment in equity method investment	0
Distributions from return of investment in equity method investment	0
Other comprehensive (loss)	0
Amortization of basis difference	0
Capitalized interest	0
Ending balance	$ 1,100
Land2Gas
Schedule of Equity Method Investments [Line Items]
Percentage of ownership	50.00%
Increase (Decrease) In Equity Method Investments [Roll Forward]
Beginning balance	$ 16,384
Income (loss) from equity method investments	(1,411)
Contribution by the Company	15,300
Distributions from return on investment in equity method investment	0
Distributions from return of investment in equity method investment	0
Other comprehensive (loss)	0
Amortization of basis difference	0
Capitalized interest	1,356
Ending balance	$ 31,629
Paragon
Schedule of Equity Method Investments [Line Items]
Percentage of ownership	50.00%
Increase (Decrease) In Equity Method Investments [Roll Forward]
Beginning balance	$ 164,817
Income (loss) from equity method investments	3,859
Contribution by the Company	0
Distributions from return on investment in equity method investment	(3,859)
Distributions from return of investment in equity method investment	(6,236)
Other comprehensive (loss)	(287)
Amortization of basis difference	(4,595)
Capitalized interest	0
Ending balance	$ 153,699

Derivative Financial Instruments and Fair Value Measurements - Interest Rate Swaps (Details) - Interest rate swap contracts - Cash Flow Hedging - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Derivative [Line Items]
Prepaid expenses and other current assets	$ 84	$ 238
Other long-term assets	0	448
Other long-term liabilities	(95)	0
Total derivatives	$ (11)	$ 686

Income taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Income taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income tax benefit	$ 14,567	$ 8,906	$ 36,290	$ 8,906
Effective tax rate	0.00%	0.00%	0.00%	0.00%

Summary of Significant Accounting Policies - Receivables, Contract Assets and Contract Liabilities From Contracts With Customers (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Accounting Policies [Abstract]
Accounts receivable, net	$ 31,113	$ 32,013
Contract assets:
Cost and estimated earnings in excess of billings	11,171	8,547
Accounts receivable retainage, net	1,475	2,528
Contract assets	12,646	11,075
Contract liabilities:
Billings in excess of costs and estimated earnings	8,378	9,276
Contract liabilities	$ 8,378	$ 9,276

Borrowings - Interest Expense on Borrowings (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Debt Instrument [Line Items]
Commitment fees and other finance fees	$ 449	$ 667	$ 1,405	$ 2,141
Amortization of deferred financing cost	722	191	1,524	1,310
Interest expense on finance leases	25	144	235	432
Interest income	(286)	(428)	(941)	(1,578)
Total interest and financing expense	6,898	5,026	19,330	13,976
Interest capitalized	841	1,019	2,082	3,093
Sunoma Loan
Debt Instrument [Line Items]
Interest expense	420	429	1,228	1,330
OPAL Term Loan
Debt Instrument [Line Items]
Interest expense	$ 5,568	$ 4,023	$ 15,879	$ 10,341

Related Parties - Narrative (Details)			3 Months Ended		9 Months Ended
Related Parties - Narrative (Details)	Aug. 23, 2025 vote vote_per_share shares	Apr. 23, 2025 vote shares	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Mar. 17, 2025
Related Party Transaction [Line Items]
Total revenues			$ 83,357,000	$ 84,047,000	$ 249,220,000	$ 219,949,000
Termination written notice, term							90 days
Business acquisition, hourly rate fee, maximum					50
Class D Common Stock
Related Party Transaction [Line Items]
Conversion of stock, shares converted (in shares) \| shares	50,000,000	50,000,000
Common stock, number of votes per share	5	5
Class B Common Stock
Related Party Transaction [Line Items]
Common stock, number of votes per share \| vote	1	1
Exercise Year 1
Related Party Transaction [Line Items]
Business acquisition, internal rate of return							10.00%
Exercise Year 2
Related Party Transaction [Line Items]
Business acquisition, internal rate of return							15.00%
Exercise Year 3
Related Party Transaction [Line Items]
Business acquisition, internal rate of return							20.00%
Wasatch Interest
Related Party Transaction [Line Items]
Ownership percentage							50.00%
Project Interest
Related Party Transaction [Line Items]
Ownership percentage							50.00%
RNG fuel
Related Party Transaction [Line Items]
Total revenues			22,921,000	25,864,000	75,650,000	63,036,000
Related Party \| RNG fuel
Related Party Transaction [Line Items]
Total revenues			17,950,000	$ 22,798,000	55,929,000	$ 54,174,000
Commodity Contract \| Related Party \| RNG fuel
Related Party Transaction [Line Items]
Total revenues			$ 4,982,000		$ 15,585,000

Redeemable non-controlling interests, Redeemable preferred non-controlling interests and Stockholders' Equity (Deficit) - Narrative (Details) $ / shares in Units, $ in Thousands				9 Months Ended
	Aug. 23, 2025 vote vote_per_share shares	Apr. 23, 2025 vote shares	Nov. 17, 2023 USD ($)	Sep. 30, 2025 USD ($) $ / shares shares	Sep. 30, 2024 USD ($) $ / shares shares	Dec. 31, 2024 shares
Preferred Units [Line Items]
Proceeds from issuance of shares of Class A common stock under the ATM program, net \| $				$ 58	$ 170
Redemption price (in dollars per share) \| $ / shares				$ 2.37
B. Riley Securities, Inc., Cantor Fitzgerald & Co. And Stifel, Nicolaus & Company, Incorporated ("Agent") \| Scenario, Plan
Preferred Units [Line Items]
Aggregate offering price \| $			$ 75,000
Class D Common Stock
Preferred Units [Line Items]
Conversion of stock, shares converted (in shares)	50,000,000	50,000,000
Common stock, number of votes per share	5	5
Common stock, shares issued (in shares)				22,899,037		72,899,037
Common stock, shares outstanding (in shares)				22,899,037		72,899,037
Class B common stock
Preferred Units [Line Items]
Common stock, number of votes per share \| vote	1	1
Common stock, shares issued (in shares)				121,500,000		71,500,000
Common stock, shares outstanding (in shares)				121,500,000		71,500,000
Class A Common Stock
Preferred Units [Line Items]
Common stock, shares issued (in shares)				30,631,960		30,065,260
Common stock, shares outstanding (in shares)				28,996,177		28,429,477
Class A Common Stock \| B. Riley Securities, Inc., Cantor Fitzgerald & Co. And Stifel, Nicolaus & Company, Incorporated ("Agent")
Preferred Units [Line Items]
Sale of stock, percentage of gross proceeds on sale			3.00%
Stock issued (in shares)				17,104	36,353
Sales price (in dollars per share) \| $ / shares				$ 3.52
Proceeds from issuance of shares of Class A common stock under the ATM program, net \| $				$ 58	$ 170
Class A Common Stock \| B. Riley Securities, Inc., Cantor Fitzgerald & Co. And Stifel, Nicolaus & Company, Incorporated ("Agent") \| Minimum
Preferred Units [Line Items]
Sales price (in dollars per share) \| $ / shares					$ 4.34
Class A Common Stock \| B. Riley Securities, Inc., Cantor Fitzgerald & Co. And Stifel, Nicolaus & Company, Incorporated ("Agent") \| Maximum
Preferred Units [Line Items]
Sales price (in dollars per share) \| $ / shares					$ 5.68
Class C common stock
Preferred Units [Line Items]
Common stock, shares issued (in shares)				0		0
Common stock, shares outstanding (in shares)				0		0
Redeemable non-controlling interests
Preferred Units [Line Items]
Redeemable non-controlling interests adjusted value \| $				$ 342,528

Derivative Financial Instruments and Fair Value Measurements - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2025 USD ($) $ / shares yr	Dec. 31, 2024 USD ($)	Jul. 31, 2024 USD ($)
Derivative [Line Items]
Fair value of convertible notes receivable			$ 750
Proceeds from convertible debt	$ 1,377
Escrow deposit	$ 198
Sponsor Earnout Awards gain
Derivative [Line Items]
Warrants expiration period	2 years
Share Price \| Sponsor Earnout Awards gain
Derivative [Line Items]
Warrants, measurement input \| $ / shares	2.20
Expected Volatility \| Sponsor Earnout Awards gain
Derivative [Line Items]
Warrants, measurement input	0.50
Risk Free Interest Rate \| Sponsor Earnout Awards gain
Derivative [Line Items]
Warrants, measurement input	0.036
Expected Term \| Sponsor Earnout Awards gain
Derivative [Line Items]
Warrants, measurement input \| yr	1.8
Dividend Yield \| Sponsor Earnout Awards gain
Derivative [Line Items]
Warrants, measurement input	0
Minimum \| Level 3 \| Discount Rate
Derivative [Line Items]
Asset retirement obligation, measurement input	0.058
Maximum \| Level 3 \| Discount Rate
Derivative [Line Items]
Asset retirement obligation, measurement input	0.085
Interest rate swap contracts \| Cash Flow Hedging
Derivative [Line Items]
Derivative asset, current	$ 84	$ 238

Income taxes	9 Months Ended
Income taxes	Sep. 30, 2025
Income Tax Disclosure [Abstract]
Income taxes	Income taxes For the three and nine months ended September 30, 2025, the Company recorded $14,567 and $36,290 income tax benefit, respectively, as a result of the sale to a third-party purchaser of certain transferable Investment Tax Credits that had been generated by the Company from its investments in the RNG segment. For the three and nine months ended September 30, 2024, the Company recorded $8,906 income tax benefit. The effective tax rate for the three and nine months ended September 30, 2025 and 2024 was 0%. The difference between the Company’s effective tax rate and the U.S. statutory tax rate of 21% was primarily due to a full valuation allowance recorded on the Company’s net U.S. deferred tax assets. The Company evaluates the realizability of the deferred tax assets on a quarterly basis and establishes a valuation allowance when it is more likely than not that all or a portion of a deferred tax asset may not be realized. On July 4, 2025, the One Big Beautiful Bill Act (“OBBBA”) was signed into law in the U.S. The OBBBA does not have a material effect on our condensed consolidated financial statements.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477617/942-740-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478822/944-740-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 231
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-231

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12C

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12B

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477891/740-270-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479360/740-10-S99-1

Reference 10: 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 11: 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 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/740/tableOfContent

Reference 13: 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 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-21

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-17

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479360/740-10-S99-2

Reference 17: 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

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Total revenues	$ 83,357	$ 84,047	$ 249,220	$ 219,949
RNG fuel
Total revenues	22,921	25,864	75,650	63,036
RNG fuel \| Related Party
Total revenues	17,950	22,798	55,929	54,174
Fuel Station Services
Total revenues	51,722	45,395	149,426	121,794
Fuel Station Services \| Related Party
Total revenues	11,492	12,526	40,921	34,234
Renewable Power Segment
Total revenues	8,714	12,788	24,144	35,119
Renewable Power Segment \| Related Party
Total revenues	$ 2,022	$ 1,799	$ 4,676	$ 5,129

- Definition

+ References

+ Details

Reportable Segments and Geographic Information (Tables)

9 Months Ended

Sep. 30, 2025

Segment Reporting [Abstract]

Schedule of Interest Expense on Borrowings, Depreciation, Amortization and Accretion and Cash Paid for Purchases, Plant and Equipment


Nine Months Ended September 30, 2025	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Revenue from external customers	$	75,650	$	149,426	$	24,144	$	249,220	$	—	$	249,220
Intersegment revenues	415		14,679		—		15,094		—		15,094

Reconciliation of Revenue
Elimination of intersegment revenues	(415)		(14,679)		—		(15,094)		—		(15,094)
Total revenues	75,650		149,426		24,144		249,220		—		249,220

Less: (1)
Cost of sales and other operating costs	35,341		118,683		19,578		173,602		41,465		215,067
Income from equity method investments	(1,877)		—		—		(1,877)		—		(1,877)
Interest and financing expense, net	19,333		45		(48)		19,330		—		19,330
Project development and startup costs	12,101		—		—		12,101		—		12,101
Other income	—		—		(64)		(64)		(815)		(879)
Depreciation, amortization, and accretion	8,985		4,924		2,863		16,772		—		16,772
Other segment items (2)	(214)		(1,076)		—		(1,290)		6,057		4,767
Segment income (loss)	1,981		26,850		1,815		30,646		(46,707)		(16,061)

Reconciliation of profit or loss (segment income / (loss))
Income tax benefit											36,290
Net income											$	20,229


Three Months Ended September 30, 2025	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Revenue from external customers	$	22,921	$	51,722	$	8,714	$	83,357	$	—	$	83,357
Intersegment revenues	139		5,394		—		5,533		—		5,533

Reconciliation of Revenue
Elimination of intersegment revenues	(139)		(5,394)		—		(5,533)		—		(5,533)
Total revenues	22,921		51,722		8,714		83,357		—		83,357

Less: (1)
Cost of sales and other operating costs	11,774		40,230		5,917		57,921		11,858		69,779
Income from equity method investments	(637)		—		—		(637)		—		(637)
Interest and financing expense, net	6,929		(11)		(20)		6,898		—		6,898
Project development and startup costs	2,543		—		—		2,543		—		2,543

Depreciation, amortization, and accretion	3,031		1,573		962		5,566		—		5,566
Other segment items (2)	(27)		81		1		55		2,334		2,389
Segment (loss) income	(692)		9,849		1,854		11,011		(14,192)		(3,181)

Reconciliation of profit or loss (segment income / (loss))
Income tax benefit											14,567
Net income											$	11,386

(2) Other segment items for each reportable segment includes:

•Fuel Station Services - gain on RNG dispensing, and gain on asset disposal

•Corporate - information technology expense, legal and professional advisor fees, and other overhead expenses

Geographic Information: The Company's assets and revenue generating activities are domiciled in the United States.

The following table reflects certain other financial data for the reportable segments as of September 30, 2025:


	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Other segment disclosures
Investment in other entities	$	227,545	$	—	$	—	$	227,545	$	—	$	227,545
Segment assets	660,922		184,555		30,658		876,135		40,614		$	916,749

For the nine months ended September 30, 2025, the Company made the following cash payments for capital expenditures:


	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Cash paid for purchases of property, plant and equipment	$	44,259	$	16,140	$	491	$	60,890	$	—	$	60,890


Nine months ended September 30, 2024	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Revenue from external customers	$	63,036	$	121,794	$	35,119	$	219,949	$	—	$	219,949
Intersegment revenues	388		15,059		—		15,447		—		15,447
							0
Reconciliation of Revenue							0
Elimination of intersegment revenues	(388)		(15,059)		—		(15,447)		—		(15,447)
Total revenues	63,036		121,794		35,119		219,949		—		219,949

Less: (1)
Cost of sales and other operating costs	26,644		94,882		25,931		147,457		34,028		181,485
Income from equity method investments	(11,828)		—		—		(11,828)		—		(11,828)
Interest and financing expense, net	13,969		119		(112)		13,976		—		13,976
Project development and startup costs	10,523		—		—		10,523		—		10,523
Other income	—		—		(349)		(349)		(11)		(360)
Depreciation, amortization, and accretion	5,482		4,183		3,012		12,677		—		12,677
Other segment items (2)	(627)		(443)		27		(1,043)		3,733		2,690
Segment income (loss)	18,873		23,053		6,610		48,536		(37,750)		10,786

Reconciliation of profit or loss (segment income / (loss))
Income tax benefit											8,906
Net income											$	19,692


Three Months Ended September 30, 2024	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Revenue from external customers	$	25,864	$	45,395	$	12,788	$	84,047	$	—	$	84,047
Intersegment revenues	129		4,520		—		4,649		—		4,649

Reconciliation of Revenue
Elimination of intersegment revenues	(129)		(4,520)		—		(4,649)		—		(4,649)
Total revenues	25,864		45,395		12,788		84,047		—		84,047

Less: (1)
Cost of sales and other operating costs	9,985		33,609		7,774		51,368		10,715		62,083
Income from equity method investments	(3,822)		—		—		(3,822)		—		(3,822)
Interest and financing expense, net	4,958		95		(27)		5,026		—		5,026
Project development and startup costs	6,803		—		—		6,803		—		6,803
Other income	—		—		(349)		(349)		(11)		(360)
Depreciation, amortization, and accretion	2,124		1,574		999		4,697		—		4,697
Other segment items (2)	(300)		(145)		(2)		(447)		1,866		1,419
Segment income (loss)	6,116		10,262		4,393		20,771		(12,570)		8,201

Reconciliation of profit or loss (segment income / (loss))
Income tax benefit											8,906
Net income											$	17,107

(2) Other segment items for each reportable segment includes:

•Fuel Station Services - gain on recognition of RINs

•Corporate - gain on mark-to-market for OPAL and Sponsor Earnout Awards, loss on extinguishment of debt, insurance other overhead expenses

The following table reflects certain other financial data for the reportable segments as of December 31, 2024:


	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Other segment disclosures
Investment in other entities	$	223,594	$	—	$	—	$	223,594	$	—	$	223,594
Segment assets	635,927		179,304		30,517		$	845,748	$	35,329	$	881,077

For the nine months ended September 30, 2024, the Company made the following cash payments for capital expenditures:


	RNG Fuel		Fuel Station Services		Renewable Power		Total Segments		Corporate		Consolidated
Cash paid for purchases of property, plant and equipment	$	56,195	$	16,610	$	—	$	72,805	$	—	$	72,805

Schedule of Revenue by Major Customers by Reporting Segments

The tables below outline the revenue from our major customer, along with respective percentages of revenue by each segment.


	Nine Months Ended September 30,
	2025				2024
Customer A	Revenue		Percentage of total revenue		Revenue		Percentage of total revenue
RNG Fuel	$	55,658	22	%	$	54,174	25	%
Fuel Station Services	34,653		14	%	27,885		13	%
Renewable Power	4,676		2	%	5,129		2	%
Total	$	94,987	38	%	$	87,188	40	%


	Three Months Ended September 30,
	2025				2024
Customer A	Revenue		Percentage of total revenue		Revenue		Percentage of total revenue
RNG Fuel	$	17,825	21	%	$	22,798	27	%
Fuel Station Services	9,198		11	%	10,616		13	%
Renewable Power	2,022		2	%	1,799		2	%
Total	$	29,045	34	%	$	35,213	42	%

Customer B was below 10% of the consolidated revenues in three and nine months ended September 30, 2025:


	Three Months Ended September 30,			Nine Months Ended September 30,
	2024			2024
Customer B	Revenue	Percentage of total revenue		Revenue	Percentage of total revenue
Fuel Station Services	11,503	14	%	31,880	14	%

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Statement of Comprehensive Income [Abstract]
Dividends attributable to redeemable non-controlling interests	$ 2,179	$ 2,186	$ 6,538	$ 6,561

Redeemable non-controlling interests, Redeemable preferred non-controlling interests and Stockholders' Equity (Deficit)

9 Months Ended

Sep. 30, 2025

Equity [Abstract]

Redeemable non-controlling interests, Redeemable preferred non-controlling interests and Stockholders' Equity (Deficit)

Common stock

Share conversion

As of September 30, 2025, there are (i) 30,631,960 shares of Class A common stock issued and 28,996,177 outstanding, (ii) 121,500,000 shares of Class B common stock issued and outstanding (shares of Class B common stock do not have any economic value except voting rights as described below), (iii) no shares of Class C common stock issued and

outstanding and (iv) 22,899,037 shares of Class D common stock (shares of Class D common stock do not have any economic value except voting rights as described below).

ATM Program

On November 17, 2023, the Company entered into an At Market Issuance Sales Agreement (the “Sales Agreement”) with B. Riley Securities, Inc., Cantor Fitzgerald & Co. and Stifel, Nicolaus & Company, Incorporated (each, an “Agent,” and collectively, the “Agents”) pursuant to which the Company may issue and sell shares of its Class A common stock having an aggregate offering price of up to $75 million from time to time through the Agents.

The Company will pay each Agent, upon the sale by such Agent of Class A common stock pursuant to the Sales Agreement, an amount equal to up to 3.0% of the gross proceeds of each such sale of Class A common stock. The Company has also provided the Agents with customary indemnification rights.

The Company issued 17,104 shares of Class A common stock under the ATM Program during the nine months ended September 30, 2025 at a price of $3.52 and received net proceeds of $58.

The Company issued 36,353 shares of Class A common stock under the ATM Program during the nine months ended September 30, 2024 at prices ranging between $4.34 and $5.68 and received net proceeds of $170.

Redeemable preferred non-controlling interests


	Series A-1 preferred units			Series A preferred units
	Units	Amount		Units	Amount		Total
Balance, December 31, 2024	300,000	$	30,000	1,000,000	$	100,000	$	130,000
Preferred dividends attributable to Redeemable non-controlling interest	—	1,509		—	5,029		6,538
Preferred dividends attributable to Class A common stockholders	—	303		—	1,010		1,313
Payment of preferred dividends	—	(1,812)		—	(6,039)		(7,851)
Balance, September 30, 2025	300,000	$	30,000	1,000,000	$	100,000	$	130,000

Redeemable non-controlling interests

At each balance sheet date, the Redeemable non-controlling interests are adjusted up to their redemption value if necessary, with an offset in stockholders' deficit. As of September 30, 2025, the Company recorded $342,528 as the redemption value based on a five-day VWAP of $2.37 per share.

Subsequent Events (Details) - Subsequent Event - MMBTU MMBTU in Millions	Oct. 31, 2025	Oct. 06, 2025
RNG Facility
Subsequent Event [Line Items]
Renewable power project, energy measure		0.3
Renewable power project, ownership percentage		50.00%
CMS
Subsequent Event [Line Items]
Renewable power project, energy measure	0.7
Renewable power project, ownership percentage	70.00%

Commitments and Contingencies - Future Minimum Lease Payments - Operating Leases (Details) $ in Thousands	Sep. 30, 2025 USD ($)
Lessee, Lease, Description [Line Items]
Three months ending December 31, 2025	$ 805
2026	2,620
2027	2,129
2028	1,476
2029	1,129
2030	1,129
Thereafter	18,267
Future minimum lease payments	27,555
Site leases
Lessee, Lease, Description [Line Items]
2025, operating lease	261
2026, operating lease	1,044
2027, operating lease	1,094
2028, operating lease	1,129
2029, operating lease	1,129
2030, operating lease	1,129
2030 and beyond, operating lease	18,267
Future minimum lease payments, operating lease	24,053
Office leases
Lessee, Lease, Description [Line Items]
2025, operating lease	141
2026, operating lease	47
2027, operating lease	0
2028, operating lease	0
2029, operating lease	0
2030, operating lease	0
2030 and beyond, operating lease	0
Future minimum lease payments, operating lease	188
Vehicle and Equipment leases
Lessee, Lease, Description [Line Items]
2025, finance lease	403
2026, finance lease	1,529
2027, finance lease	1,035
2028, finance lease	347
2029, finance lease	0
2030, finance lease	0
2030 and beyond, finance lease	0
Future minimum lease payments, finance lease	$ 3,314

Reportable Segments and Geographic Information - Narrative (Details)	9 Months Ended
	Sep. 30, 2025 segment
Segment Reporting [Abstract]
Number of operating segments	3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Cash flows from operating activities:
Net income	$ 20,229	$ 19,692
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization, and accretion	16,772	12,677
Stock-based compensation	4,858	4,312
Allowance for accounts receivable	2,454	0
Income from equity method investments	(1,877)	(11,828)
Distributions from return on investment in equity method investments	8,059	13,661
Gain on nonmonetary asset	(1,100)	0
Gain on lease termination	(600)	0
Reduction of carrying amount of operating lease right-of-use assets	575	555
Write-offs of capitalized costs	299	0
Amortization of deferred financing costs	1,524	1,310
Paid-in-kind interest income	(156)	(207)
Change in fair value of commodity swaps	(921)	494
Gain on note receivable	(815)	(11)
Unrealized gain on derivative financial instruments	(281)	(1,457)
Changes in operating assets and liabilities
Accounts receivable	(3,536)	(11,986)
Accounts receivable, related party	(7,169)	3,563
Fuel tax credits receivable	2,375	(620)
Contract assets	(1,571)	(2,858)
Parts inventory	(1,788)	(300)
Prepaid expense and other current and long-term assets	8,593	(3,751)
Accounts payable	(1,138)	(775)
Accounts payable, related party	(507)	1,356
Fuel tax credits payable	(1,353)	(34)
Accrued payroll	(969)	(1,053)
Accrued expenses and other current and non-current liabilities	(468)	9,859
Operating lease liabilities - current and non-current	(574)	(517)
Contract liabilities	(898)	(165)
Net cash provided by operating activities	40,017	31,917
Cash flows from investing activities:
Purchase of property, plant, and equipment	(60,890)	(72,805)
Payment for short-term investments	0	(791)
Distributions from return of investment in equity method investment	6,236	1,756
Cash paid to equity method investments	(16,656)	(13,956)
Cash received from (paid for) note receivable	1,377	(750)
Net cash used in investing activities	(69,933)	(86,546)
Cash flows from financing activities:
Proceeds from OPAL Term Loan and Revolving loan	60,000	45,000
Financing costs paid to other third parties	(1,250)	(629)
Repayment of OPAL Revolving Loan	(15,000)	0
Repayment of Sunoma Loan	(1,295)	(1,193)
Repayment of principal portion of finance lease liabilities	(1,144)	(43)
Payment of preferred dividends	(7,852)	(10,469)
Distribution to non-redeemable non-controlling interest	(150)	(628)
Capital contribution from non-redeemable non-controlling interests	1,991	0
Proceeds from issuance of shares of Class A common stock under the ATM program, net	58	170
Cash paid for taxes related to net share settlement of equity awards	(387)	(627)
Net cash provided by financing activities	34,971	31,581
Net increase (decrease) in cash, restricted cash, and cash equivalents	5,055	(23,048)
Cash, restricted cash, and cash equivalents, beginning of period	29,228	47,242
Cash, restricted cash, and cash equivalents, end of period	34,283	24,194
Supplemental disclosure of cash flow information
Interest paid, net of $2,082 and $3,093 capitalized, respectively	20,523	8,628
Tax benefit received	36,290	8,906
Noncash investing and financing activities:
Accrual for asset retirement obligation included in property, plant and equipment	0	499
Right-of-use assets arising from lease modifications	0	1,218
Right-of-use assets for finance leases included in property, plant and equipment	58	0
Accrual for purchase of property, plant and equipment included in accrued and payable capital expenditures	$ 10,014	$ 24,721

Net Income Per Share - Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares (in shares)	483,502	507,121	483,502	507,121
Unvested PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares (in shares)	1,954,966	2,918,668	1,954,966	2,918,668
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares (in shares)	1,068,958	1,558,615	1,068,958	1,564,331
OPAL Fuels Class B units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares (in shares)	144,399,037	144,399,037	144,399,037	144,399,037

Stock-based compensation (Tables)

9 Months Ended

Sep. 30, 2025

Share-Based Payment Arrangement [Abstract]

Schedule of Stock-Based Compensation Expense

The stock-based compensation expense for the above stock awards under the 2022 Plan as well as Parent Equity Awards is included in the selling, general and administrative expenses:


	Three months ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
2022 Plan	$	902	$	1,457	$	4,729	$	4,043
Parent Equity Awards	—		—		129		269
Total	$	902	$	1,457	$	4,858	$	4,312

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenues:
Total revenues	$ 83,357	$ 84,047	$ 249,220	$ 219,949
Operating expenses:
Project development and startup costs	2,543	6,803	12,101	10,523
Selling, general, and administrative	14,376	12,692	47,803	39,552
Depreciation, amortization, and accretion	5,566	4,697	16,772	12,677
Income from equity method investments	(637)	(3,822)	(1,877)	(11,828)
Total operating expenses	79,769	71,738	248,401	198,381
Operating income	3,588	12,309	819	21,568
Other (expense) income:
Interest and financing expense, net	(6,898)	(5,026)	(19,330)	(13,976)
Change in fair value of derivative instruments, net	0	278	281	1,457
Other income	129	640	2,169	1,737
Total other expenses	(6,769)	(4,108)	(16,880)	(10,782)
(Loss) income before income tax benefit	(3,181)	8,201	(16,061)	10,786
Income tax benefit	14,567	8,906	36,290	8,906
Net income	11,386	17,107	20,229	19,692
Net income attributable to redeemable non-controlling interests	7,226	11,998	10,034	9,618
Net income attributable to non-redeemable non-controlling interests	93	130	329	328
Dividends on redeemable preferred non-controlling interests	2,617	2,617	7,851	7,853
Net income attributable to Class A common stockholders	$ 1,450	$ 2,362	$ 2,015	$ 1,893
Weighted average shares outstanding of Class A common stock:
Basic (in shares)	28,279,527	27,709,203	28,090,014	27,585,620
Diluted (in shares)	29,592,822	27,743,417	29,013,705	27,644,164
Per share amounts:
Basic (in dollars per share)	$ 0.05	$ 0.09	$ 0.07	$ 0.07
Diluted (in dollars per share)	$ 0.05	$ 0.09	$ 0.07	$ 0.07
RNG fuel
Revenues:
Total revenues	$ 22,921	$ 25,864	$ 75,650	$ 63,036
Operating expenses:
Cost of sales	11,774	9,985	35,341	26,644
Fuel Station Services
Revenues:
Total revenues	51,722	45,395	149,426	121,794
Operating expenses:
Cost of sales	40,230	33,609	118,683	94,882
Renewable Power Segment
Revenues:
Total revenues	8,714	12,788	24,144	35,119
Operating expenses:
Cost of sales	$ 5,917	$ 7,774	$ 19,578	$ 25,931

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2025
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On October 6, 2025, the Company's Atlantic RNG facility commenced commercial operations. This project represents approximately 0.3 million MMBtu for Opal's 50% ownership share of annual design capacity. In October 2025, the Company began construction of the CMS Concord RNG facility in North Carolina. This project represents approximately 0.7 million MMBtu for Opal's 70% ownership share of annual design capacity. There have been no other subsequent events, that occurred during such period that would require disclosure in this Form 10-Q or would be required to be recognized in the consolidated financial statements as of and for the three and nine months ended September 30, 2025.

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2025	Nov. 07, 2025
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2025
Document Transition Report	false
Entity File Number	001-40272
Entity Registrant Name	OPAL FUELS INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	98-1578357
Entity Address, Address Line One	One North Lexington Avenue
Entity Address, Address Line Two	Suite 1450
Entity Address, City or Town	White Plains
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10601
City Area Code	914
Local Phone Number	705-4000
Title of 12(b) Security	Class A Common Stock, par value $0.0001 per share
Trading Symbol	OPAL
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Central Index Key	0001842279
Amendment Flag	false
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		28,996,177
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		121,500,000
Class D Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		22,899,037

Investment in Other Entities

9 Months Ended

Sep. 30, 2025

Equity Method Investments and Joint Ventures [Abstract]

Investments in Other Entities

Investment in Other Entities

The following table shows the movement in Investment in Other Entities:


	Pine Bend			Noble Road			GREP			Land2Gas			Paragon			Total
Percentage of ownership	50		%	50		%	20		%	50		%	50		%

Balance at December 31, 2024	$	19,536		$	21,097		$	1,760		$	16,384		$	164,817		$	223,594
Income (loss) from equity method investments	2,354			2,892			(660)			(1,411)			3,859			7,034
Contribution by the Company	—			—			—			15,300			—			15,300
Distributions from return on investment in equity method investment (1)	(1,625)			(2,575)			—			—			(3,859)			(8,059)
Distributions from return of investment in equity method investment (2)	—			—			—			—			(6,236)			(6,236)
Other comprehensive (loss)	—			—			—			—			(287)			(287)
Amortization of basis difference (3)	(118)			(444)			—			—			(4,595)			(5,157)
Capitalized interest	—			—			—			1,356			—			1,356
Balance at September 30, 2025	$	20,147		$	20,970		$	1,100		$	31,629		$	153,699		$	227,545

(1) Recorded as part of cash flows from operating activities for the nine months ended September 30, 2025.

(2) Recorded as part of cash flows from investing activities for the nine months ended September 30, 2025.

(3) Reflected in income from equity method investments in the condensed consolidated statements of operations for the nine months ended September 30, 2025.

The following table summarizes the statement of operations information for equity method investments and the Company's portion of net income from equity method investments:


	Three Months Ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
Revenue	$	26,570	$	26,123	$	80,844	$	77,097
Gross profit	6,785		10,799		21,167		31,812
Net income	2,508		7,182		8,791		26,579
Net income from equity method investments(1)	$	637	$	3,822	$	1,877	$	11,828

(1) Net income from equity method investments represents the Company's portion of the net income from equity method investments including amortization of any basis differences.

A summary of financial information for our portion of the assets and liabilities in equity method investees in the aggregate is as follows:


	September 30, 2025		December 31, 2024
Current assets	$	8,662	$	10,554
Noncurrent assets	136,295		121,934
Total assets	144,957		132,488
Current liabilities	11,121		15,993
Noncurrent liabilities	33,991		24,612
Total liabilities	$	45,112	$	40,605

Commitments and Contingencies - Narrative (Details) - USD ($)					9 Months Ended	12 Months Ended
	Sep. 12, 2025	Jun. 20, 2025	Mar. 28, 2025	Sep. 13, 2024	Sep. 30, 2025	Dec. 31, 2024
Line of Credit Facility [Line Items]
Investment tax credit, purchase agreement			$ 9,801,000
Proceeds from investment tax credit			$ 8,037,000
Estimated loss per contract					$ 4,900,000
Estimated loss from claim					2,000,000
Apollo Management Holdings, L..P.
Line of Credit Facility [Line Items]
Investment tax credit, purchase agreement	$ 17,369,000	$ 16,740,000		$ 11,096,000
Proceeds from investment tax credit	14,567,000	13,686,000		$ 8,906,000
EagleBank
Line of Credit Facility [Line Items]
Investment tax credit, purchase agreement		16,740,000
Proceeds from investment tax credit		$ 13,686,000
Athene Annuity and Life Company
Line of Credit Facility [Line Items]
Investment tax credit, purchase agreement	17,369,000
Proceeds from investment tax credit	$ 14,567,000
V E C Partners Inc Dba C E I Builders C E I \| M D Digester L L C
Line of Credit Facility [Line Items]
Estimated loss per contract					14,000,000
MD and VS Projects
Line of Credit Facility [Line Items]
Estimated loss from claim					3,141,000
Standby Letters of Credit
Line of Credit Facility [Line Items]
Standby letters of credit outstanding balance					15,485,000	$ 15,120,000
Draws on standby letters of credit					$ 0	$ 0

Investment in Other Entities (Tables)

9 Months Ended

Sep. 30, 2025

Equity Method Investments and Joint Ventures [Abstract]

Schedule of Equity Method Investments

The following table shows the movement in Investment in Other Entities:


	Pine Bend			Noble Road			GREP			Land2Gas			Paragon			Total
Percentage of ownership	50		%	50		%	20		%	50		%	50		%

Balance at December 31, 2024	$	19,536		$	21,097		$	1,760		$	16,384		$	164,817		$	223,594
Income (loss) from equity method investments	2,354			2,892			(660)			(1,411)			3,859			7,034
Contribution by the Company	—			—			—			15,300			—			15,300
Distributions from return on investment in equity method investment (1)	(1,625)			(2,575)			—			—			(3,859)			(8,059)
Distributions from return of investment in equity method investment (2)	—			—			—			—			(6,236)			(6,236)
Other comprehensive (loss)	—			—			—			—			(287)			(287)
Amortization of basis difference (3)	(118)			(444)			—			—			(4,595)			(5,157)
Capitalized interest	—			—			—			1,356			—			1,356
Balance at September 30, 2025	$	20,147		$	20,970		$	1,100		$	31,629		$	153,699		$	227,545

(1) Recorded as part of cash flows from operating activities for the nine months ended September 30, 2025.

(2) Recorded as part of cash flows from investing activities for the nine months ended September 30, 2025.

(3) Reflected in income from equity method investments in the condensed consolidated statements of operations for the nine months ended September 30, 2025.

The following table summarizes the statement of operations information for equity method investments and the Company's portion of net income from equity method investments:


	Three Months Ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
Revenue	$	26,570	$	26,123	$	80,844	$	77,097
Gross profit	6,785		10,799		21,167		31,812
Net income	2,508		7,182		8,791		26,579
Net income from equity method investments(1)	$	637	$	3,822	$	1,877	$	11,828

(1) Net income from equity method investments represents the Company's portion of the net income from equity method investments including amortization of any basis differences.

A summary of financial information for our portion of the assets and liabilities in equity method investees in the aggregate is as follows:


	September 30, 2025		December 31, 2024
Current assets	$	8,662	$	10,554
Noncurrent assets	136,295		121,934
Total assets	144,957		132,488
Current liabilities	11,121		15,993
Noncurrent liabilities	33,991		24,612
Total liabilities	$	45,112	$	40,605

Leases

9 Months Ended

Sep. 30, 2025

Leases [Abstract]

Leases

Lessor contracts

Fuel provider agreements

Power purchase agreements


	Three months ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
FPAs (1)	$	5,240	$	1,154	$	10,044	$	2,861
PPAs (2)	$	228	$	267	$	875	$	696

(1) Included in Fuel Station Service revenues

(2) Included in Renewable Power revenues

Lessee contracts

Leases

Lessor contracts

Fuel provider agreements

Power purchase agreements


	Three months ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
FPAs (1)	$	5,240	$	1,154	$	10,044	$	2,861
PPAs (2)	$	228	$	267	$	875	$	696

(1) Included in Fuel Station Service revenues

(2) Included in Renewable Power revenues

Lessee contracts

Leases

Lessor contracts

Fuel provider agreements

Power purchase agreements


	Three months ended September 30,				Nine months ended September 30,
	2025		2024		2025		2024
FPAs (1)	$	5,240	$	1,154	$	10,044	$	2,861
PPAs (2)	$	228	$	267	$	875	$	696

(1) Included in Fuel Station Service revenues

(2) Included in Renewable Power revenues

Lessee contracts