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Clean Energy Fuels Corp

For the period ended Dec 31, 2023. Filed Feb 29, 2024.

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A company's yearly report to the SEC, with audited financial statements. It is the fullest account a company gives of its business, its finances and the risks it sees.

FY2023 · Filed Feb 29, 2024

CLNE$1.93+1.0%Stored close · as of Nov 9, 2026

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Contents

Notes to Consolidated Financial Statements

Note 1 —Summary of Significant Accounting Policies

The Company and Nature of Business

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

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

Basis of Presentation

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

Use of Estimates

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

Inventory

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

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

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

Derivative Instruments and Hedging Activities

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

Property and Equipment

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

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

Leases

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

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

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

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

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

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

Long-Lived Assets

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

There wereno impairments of the Company’s long-lived assets in the years ended December 31, 2021, 2022 and 2023.

Intangible assets with finite useful lives are amortized over their respective estimated useful lives using the straight-line method. The estimated useful lives of intangible assets with finite useful lives areone toeight years for customer relationships, one tofifty years for acquired contracts, two toten years for trademarks and trade names, andthree years for non-compete agreements.

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

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

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

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

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

Goodwill

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

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

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

During the years ended December 31, 2021, 2022 and 2023, the Company utilized the quantitative approach and concluded that there wereno impairments to goodwill.

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

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

Revenue Recognition

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

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

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

Product Revenue

Volume-Related

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

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

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

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

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

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

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

Station Construction Sales

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

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

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

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

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

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

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

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

Service Revenue

O&M Services

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

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

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

Other services

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

Alternative Fuel Excise Tax Credit

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

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

LNG Transportation Costs

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

Advertising Costs

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

Stock-Based Compensation

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

Amazon Warrant

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

Stonepeak Warrant

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

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

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

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

Income Taxes

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

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

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

Net Loss Per Share

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

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

Foreign Currency Translation and Transactions

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

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

Comprehensive Loss

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

Concentration of Credit Risk

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

Recently Issued Accounting Pronouncements

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

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

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

Note 2 —Revenue from Contracts with Customers

Disaggregation of Revenue

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

​​​​​​​​​​
​ · ​ · Year Ended December 31,
​ · ​ · 2021 · 2022 · 2023
Product revenue:​​​​​​​​​
Volume-related​​​​​​​​​
Fuel sales(1)​$130,973​$281,103​$286,956
Change in fair value of derivative instruments(2)​​(3,490)​​517​​(158)
RIN Credits​​31,736​​34,635​​25,860
LCFS Credits​​16,808​​12,634​​9,885
AFTC (3)​20,700​21,760​20,854
Total volume-related product revenue​​196,727​​350,649​​343,397
Station construction sales​​16,406​​22,346​​26,427
Total product revenue​213,133​372,995​369,824
Service revenue:​​​​​​​​​
Volume-related, O&M services​​41,934​​45,901​​52,660
Other services​​579​​1,268​​2,675
Total service revenue​​42,513​​47,169​​55,335
Total revenue​$255,646​$420,164​$425,159
(1)Includes non-cash stock-based sales incentive contra-revenue charges associated with the Amazon Warrant for the years ended December 31, 2021, 2022 and 2023 of $83.6 million, $24.3 million and $60.6 million, respectively. See Note 13 for more information.
(2)Represents changes in fair value of derivative instruments related to the Company’s commodity swap and customer fueling contracts associated with the Company’s Zero Now truck financing program. The amounts are classified as revenue because the Company’s commodity swap contracts are used to economically offset the risk associated with the diesel-to-natural gas price spread resulting from customer fueling contracts under the Company’s Zero Now truck financing program. See Note 1 and Note 7 for more information about these derivative instruments.
(3)Represents AFTC. See Note 1 for more information.

Remaining Performance Obligations

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

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

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

Costs to Fulfill a Contract

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

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

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

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

Contract Balances

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

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

​​​​​​​
​ · ​ · 2022 · ​ · 2023
Accounts receivable, net​$91,430​$98,426
​​​​​​
Contract assets - current​$6,063​$7,823
Contract assets - non-current​2,976​2,433
Contract assets - total​$9,039​$10,256
​​​​​​
Contract liabilities - current​$5,477​$4,936
Contract liabilities - non-current​—​151
Contract liabilities - total​$5,477​$5,087

Accounts Receivable, Net

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

Contract Assets

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

Contract Liabilities

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

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

Note 3 —Divestitures

bp Transaction

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

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

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

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

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

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

TotalEnergies Joint Venture

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

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

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

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

​​​​​​​​​​
​ · ​ · Year Ended December 31,
​ · ​ · 2021 · ​ · 2022 · ​ · 2023
Revenue​$—​$—​$1,462
Gross profit​​—​​—​​173
Operating loss​​(119)​​(454)​​(3,414)
Net loss​$(119)​$(454)​$(4,951)
​​​​​​​
​As of December 31,
​ · ​ · 2022 · ​ · 2023
Current assets​$11​$13,838
Non-current assets​32,773​33,289
Total assets​$32,784​$47,127
​​​​​​​
Current liabilities​$4,326​$2,518
Non-current liabilities​19,493​29,595
Total liabilities​$23,819​$32,113

bp Joint Venture

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

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

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

​​​​​​​​​​
​ · ​ · Year Ended December 31,
​ · ​ · 2021 · ​ · 2022 · ​ · 2023
Revenue​$—​$—​$—
Gross profit​​—​​—​​—
Operating loss​​(678)​​(7,210)​​(15,074)
Net loss​​(603)​​(5,485)​​(10,241)
Net loss attributable to bpJV​$(599)​$(5,426)​$(9,127)
​​​​​​​​​​
​​​As of December 31,
​​​​2022​2023
Current assets​​​$157,241​$209,973
Non-current assets​​​​​207,464​​296,240
Total assets​​​​$364,705​$506,213
​​​​​​​​​​
Current liabilities​​​​$22,698​$27,706
Non-current liabilities​​​​​2,716​​13,558
Total liabilities​​​​$25,414​$41,264
​​​​​​​​​​
Equity attributable to shareowners of bpJV​​​​$313,544​$440,613
Equity attributable to noncontrolling interest​​​​​25,747​​24,336
Total equity​​​​$339,291​$464,949

SAFE&CEC S.r.l.

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

​​​​​​​​​​
​ · ​ · Year Ended December 31,
​ · ​ · 2021 · ​ · 2022 · ​ · 2023
Revenue​$109,119​$110,104​$97,740
Gross profit​​25,784​​24,902​​24,098
Operating income​​4,728​​2,513​​(562)
Net income (loss)​$2,392​$951​$(2,148)
​​​​​​​​​​
​ · ​ · ​ · ​ · As of December 31,
​ · ​ · ​ · ​ · ​ · 2022 · ​ · 2023
Current assets​​​$82,514​$79,981
Non-current assets​​​​​60,187​​59,636
Total assets​​​​$142,701​$139,617
​​​​​​​​​​
Current liabilities​​​​$73,931​$70,193
Non-current liabilities​​​​​20,248​​20,888
Total liabilities​​​​$94,179​$91,081

Other Equity Method Investments

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

​​​​​​​​​​
​Year Ended December 31,
​ · ​ · 2021 · ​ · 2022 · ​ · 2023
Revenue​$704​$1,217​$615
Gross profit​​216​​506​​327
Operating loss​​(1,757)​​(2,556)​​(4,513)
Net loss​$(1,793)​$(2,585)​$(4,539)
​​​​​​​
​As of December 31,
​ · ​ · 2022 · ​ · 2023
Current assets​$1,652​$1,436
Non-current assets​4,609​4,281
Total assets​$6,261​$5,717
​​​​​​​
Current liabilities​$1,169​$1,231
Non-current liabilities​2,383​6,312
Total liabilities​$3,552​$7,543

NG Advantage

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

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

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

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

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

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

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

For the year ended December 31, 2022, NG Advantage borrowed $29.1 million from the Company under a series of advance agreements. There wereno borrowings by NG Advantage in the year ended December 31, 2023. As of December 31, 2022 and 2023, NG advantage had a total outstanding principal balance of $47.5 million, plus accrued and unpaid interest under the advance agreements. These intercompany transactions have been eliminated in consolidation.

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

Investments in Equity Securities

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

Note 5 —Cash, Cash Equivalents and Restricted Cash

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

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

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

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

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

Note 6 —Short-Term Investments

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

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

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

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

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

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

Note 7 —Derivative Instruments and Hedging Activities

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

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

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

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

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

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

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

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

​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​
​ · ​ · December 31, 2022 · ​ · December 31, 2023
​ · ​ · Volumes · ​ · Weighted-Average Price per · ​ · Volumes · ​ · Weighted-Average Price per
Year · (Diesel Gallons) · Diesel Gallon · (Diesel Gallons) · Diesel Gallon
20235,000,000​$3.18—​$—
20241,875,000​$3.18​1,875,000​$3.18

Note 8 —Fair Value Measurements

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

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

Assets and Liabilities Measured at Fair Value on a Recurring Basis

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

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

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

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

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

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

Convertible Promissory Note

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

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

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

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

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

There wereno transfers of assets or liabilities between Level 1, Level 2, and Level 3 of the fair value hierarchy as of December 31, 2022 or 2023.

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

​​​​​​​​​​​​​
​ · December 31, 2022 · Level 1 · Level 2 · Level 3
Assets: · ​ · ​ · ​ · ​
Available-for-sale securities: · ​ · ​ · ​ · ​
U.S. government securities(1)​$64,880​$64,880​$—​$—
Zero coupon bonds(1)​74,159​—​74,159​—
Convertible promissory note(4)​1,880​—​—​1,880
Certificates of deposit (1)​530​—​530​—
Embedded derivatives (3)​​6,755​​—​​—​​6,755
Liabilities:​​​​​
Commodity swap contracts (2)​$3,845​$—​$—​$3,845
​​​​​​​​​​​​​
​ · December 31, 2023 · Level 1 · Level 2 · Level 3
Assets: · ​ · ​ · ​
Available-for-sale securities: · ​ · ​ · ​ · ​
U.S. government securities(1)​$157,656​$157,656​$—​$—
Convertible promissory note(4)​​2,330​​—​​—​​2,330
Certificates of deposit (1)​​530​​—​​530​​—
Embedded derivatives (3)​​4,628​​—​​—​​4,628
Liabilities:​​​​​​​​​​​​
Commodity swap contracts (2)​$1,875​$—​$—​$1,875
(1)Included in “Short-term investments” in the accompanying consolidated balance sheets. See Note 6 for more information.
(2)Included in “Derivative liabilities, related party” and “Long-term portion of derivative liabilities, related party” as of December 31, 2022 and in “Derivative liabilities, related party” as of December 31, 2023 in the accompanying consolidated balance sheets. See Note 7 for more information.
(3)Included in “Prepaid expenses and other current assets” and “Notes receivable and other long-term assets, net” as of December 31, 2022 and 2023 in the accompanying consolidated balance sheets. See Note 7 for more information.
(4)Included in “Notes receivable and other long-term assets, net” as of December 31, 2022 and in “Other receivables” as of December 31, 2023 in the accompanying consolidated balance sheets.

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

​​​​​​​​​​
​ · ​ · Assets: · ​ · Assets: · ​ · Liabilities:
​ · ​ · Embedded · ​ · Convertible · ​ · Commodity
​ · Derivatives · ​ · Promissory Note · ​ · Swap Contracts
Balance as of December 31, 2021​$6,776​$—​$(4,383)
Settlements, net​​—​​—​​7,761
Total gain (loss)​​(21)​​(134)​​(7,223)
Purchases​​—​​2,014​​—
Balance as of December 31, 2022​$6,755​$1,880​$(3,845)
​​​​​​​​​​
Balance as of December 31, 2022​$6,755​$1,880​$(3,845)
Settlements, net​​—​​—​​4,858
Total gain (loss)​​(2,127)​​103​​(2,888)
Purchases​​—​​3,822​​—
Equity method investment loss​​—​​(3,475)​​—
Balance as of December 31, 2023​$4,628​$2,330​$(1,875)
​​​​​​​​​​
Change in unrealized gain (loss) for the year ended December 31, 2022 included in earnings​$(21)​$—​$538
Change in unrealized gain (loss) for the year ended December 31, 2023 included in earnings​$(2,127)​$—​$1,970
Change in unrealized gain (loss) for the year ended December 31, 2022 included in other comprehensive income (loss)​$—​$(134)​$—
Change in unrealized gain (loss) for the year ended December 31, 2023 included in other comprehensive income (loss)​$—​$103​$—

Other Financial Assets and Liabilities

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

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

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

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

Note 9 —Other Receivables

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

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

Note 10 —Land, Property and Equipment

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

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

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

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

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

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

Fueling Station Equipment Removal

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

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

Note 11 —Accrued Liabilities

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

​ · ​ · ​ · ​ · ​ · ​ · ​
​ · 2022 · 2023
Accrued alternative fuels incentives (1)​$34,239​$41,609
Accrued employee benefits​5,128​5,315
Accrued gas and equipment purchases​22,008​17,485
Accrued interest​1,827​1,451
Accrued property and other taxes​3,782​4,502
Accrued salaries and wages​6,857​8,697
Other (2)​16,238​12,475
Total accrued liabilities​$90,079​$91,534
(1)Includes amount for RINs, LCFS Credits, and AFTC payable to third parties.
(2)No individual item in “Other” exceeds 5% of total current liabilities.

Note 12 —Debt

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

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

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

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

Stonepeak Credit Agreement

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

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

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

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

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

Riverstone Credit Agreement

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

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

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

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

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

Other Debt

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

Note 13 —Stockholders’ Equity

Authorized Shares

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

Dividend Provisions

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

Voting Rights

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

TotalEnergies Private Placement

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

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

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

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

At-The-Market Offerings

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

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

Share Repurchase Program

On March 12, 2020, the Company’s Board of Directors approved a share repurchase program of up to $30.0 million (exclusive of fees and commissions) of the Company’s outstanding common stock (the “Repurchase Program”). On December 7, 2021, the Company’s Board of Directors approved an increase in the aggregate purchase amount under the Repurchase Program from $30.0 million to $50.0 million (exclusive of fees and commissions). The Repurchase Program does not have an expiration date, and it may be suspended or discontinued at any time. During the year ended December 31, 2023, there wereno repurchases of the Company’s common stock under the Repurchase Program. As of December 31, 2023, the Company has utilized a total of $23.5 million under the Repurchase Program from its inception to repurchase 9,387,340 shares of common stock, and a total of $26.5 million of authorized funds remain available for common stock repurchase under the Repurchase Program. The Repurchase Program does not obligate the Company to acquire any specific number of shares. Repurchases under the Repurchase Program may be effected from time to time through open market purchases, privately negotiated transactions, structured or derivative transactions, including accelerated share repurchase transactions, or other methods of acquiring shares, in each case subject to market conditions, applicable

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

Stock-Based Compensation

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

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

Equity Incentive Plans

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

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

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

Service-Based Stock Options

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

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

​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​
​ · ​ · ​ · ​ · ​ · ​ · ​ · Weighted · ​ · ​ · ​
​ · ​ · ​ · ​ · ​ · ​ · ​ · Average · ​ · ​ · ​
​​​​Weighted​Remaining​Aggregate
​​​​Average​Contractual​Intrinsic
​​Number of​Exercise​Term​Value
​ · Shares · Price · (in years) · (in thousands)
Options outstanding as of December 31, 202210,116,340​$6.00​
Granted3,030,439​$4.78​​​​​
Exercised(98,592)​$2.38​​​​​
Forfeited or expired(487,610)​$7.29​​​​​
Options outstanding as of December 31, 202312,560,577​$5.68​6.71​$5,369
Options exercisable as of December 31, 20238,117,695​$5.54​5.63​$5,345
Options vested and expected to vest as of December 31, 202312,560,577​$5.68​6.71​$5,369

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

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

​ · ​ · ​ · ​ · ​ · ​ · ​
​ · ​ · Year Ended December 31,
​ · 2021 · 2022 · 2023
Dividend yield0.0%​0.0%​0.0%
Expected volatility76.8% to 96.8%​73.7% to 76.9%​75.2% to 76.6%
Risk-free interest rate0.58% to 1.31%​1.52% to 4.34%​3.68% to 4.73%
Expected life in years5.6 to 5.85.6 to 5.95.9 to 6.2

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

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

Performance-Based Stock Options

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

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

​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​
​ · ​ · ​ · ​ · ​ · ​ · ​ · Weighted · ​ · ​ · ​
​ · ​ · ​ · ​ · ​ · ​ · ​ · Average · ​ · ​ · ​
​​​​Weighted​Remaining​Aggregate
​​​​Average​Contractual​Intrinsic
​​Number of​Exercise​Term​Value
​ · Shares · Price · (in years) · (in thousands)
Options outstanding as of December 31, 20221,640,000​$6.77​​
Granted—​$—​​​​​
Exercised—​$—​​​​​
Forfeited or expired(25,000)​$6.77​​​​​
Options outstanding as of December 31, 20231,615,000​$6.77​7.94​$—
Options vested and exercisable as of December 31, 2023403,750​$6.77​7.94​$—

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

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

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

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

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

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

Market-Based Stock Options

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

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

​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​ · ​
​ · ​ · ​ · ​ · ​ · ​ · ​ · Weighted · ​ · ​ · ​
​ · ​ · ​ · ​ · ​ · ​ · ​ · Average · ​ · ​ · ​
​​​​Weighted​Remaining​Aggregate
​​​​Average​Contractual​Intrinsic
​​Number of​Exercise​Term​Value
​ · Shares · Price · (in years) · (in thousands)
Options outstanding as of December 31, 20223,700,000​$6.77​​
Granted—​$—​​​​​
Exercised—​$—​​​​​
Forfeited or expired(50,000)​$6.77​​​​​
Options outstanding as of December 31, 20233,650,000​$6.77​7.94​$—
Options vested and exercisable as of December 31, 2023—​$—​—​$—

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

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

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

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

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

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

Service-Based Restricted Stock Units

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

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

​ · ​ · ​ · ​ · ​ · ​
​ · ​ · ​ · ​ · Weighted
​ · ​ · ​ · ​ · Average
​ · ​ · Number of · ​ · Fair Value at
​ · Shares · Grant Date
RSU outstanding and unvested as of December 31, 2022694,945​$8.41
Granted129,524​$4.19
Vested(418,274)​$7.38
Forfeited or expired(6,486)​$10.08
RSU outstanding and unvested as of December 31, 2023399,709​$8.10

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

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

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

Employee Stock Purchase Plan

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

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

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

Amazon Warrant

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

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

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

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

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

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

​ · ​ · ​ · ​ · ​
​ · April 16, 2021 · June 14, 2021
Dividend yield0.0%​0.0%
Expected volatility66.46%​67.97%
Risk-free interest rate1.59%​1.49%
Expected term in years10.09.8

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

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

​ · ​ · ​
​ · ​ · Warrant
​Shares
Outstanding and unvested as of December 31, 202242,314,667
Granted—
Vested(4,701,632)
Outstanding and unvested as of December 31, 202337,613,035

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

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

Stonepeak Warrant

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

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

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

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

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

​​​​​
​ · December 12, 2023 · December 12, 2023
Exercise price​5.50​6.50
Dividend yield0.0%​0.0%
Expected volatility72.96%​72.96%
Risk-free interest rate4.22%​4.22%
Expected term in years8.58.5

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

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

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

​ · ​ · ​
​ · ​ · Warrant
​Shares
Outstanding and unexercised as of December 31, 2022—
Granted20,000,000
Exercised—
Outstanding and unexercised as of December 31, 202320,000,000

Note 14 —Income Taxes

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

●The investment tax credit under Section 48 of the Internal Revenue Code is expanded to include Qualified Biogas Property, which is expected to be available for the RNG dairy projects that the Company has invested or will invest. The investment tax credit rate could range from 6% up to a 50% bonus rate depending on meeting certain wage, apprenticeship, domestic content, and energy community requirements.
●A new tax credit under Section 45Z of the Internal Revenue Code was introduced to apply to low-emissions transportation fuel produced at a qualified facility and sold by the taxpayer after December 31, 2024 through December 31, 2027. The IRA provides a base credit of 20 cents per gallon or $1.00 per gallon multiplied by an

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

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

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

Note 15 —Commitments and Contingencies

Environmental Matters

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

Litigation, Claims and Contingencies

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

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

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

Loan Commitment to an Equity Method Investee

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

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

Note 16 —Leases

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

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

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

Lessee Accounting

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

​​​​​​​
​ · ​ · 2022 · ​ · 2023
Finance leases: · ​ · ​
Land, property and equipment, gross​$5,703​$6,436
Accumulated depreciation​(2,895)​(3,199)
Land, property and equipment, net​$2,808​$3,237
​​​​​​​
Current portion of finance lease obligations​$948​$1,758
Long-term portion of finance lease obligations​2,134​1,839
Total finance lease liabilities​$3,082​$3,597
​​​​​​​
Operating leases:​​
Operating lease right-of-use assets​$52,586​$92,324
​​​​​​​
Current portion of operating lease obligations​$4,206​$6,687
Long-term portion of operating lease obligations​48,911​89,065
Total operating lease liabilities​$53,117​$95,752

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

​​​​​​​
​ · ​ · Year Ended December 31,
​ · ​ · 2022 · ​ · 2023
Finance leases: · ​ · ​
Depreciation on assets under finance leases​$877​$928
Interest on lease liabilities​164​183
Total finance leases expense​$1,041​$1,111
​​​​​​​
Operating leases:​​
Lease expense​$8,800​$15,986
Lease expense on short-term leases​513​503
Variable lease expense​4,306​4,777
Sublease income​(636)​(636)
Total operating leases expense​$12,983​$20,630

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

​​​​​​​
​ · ​ · Year Ended December 31,
​ · ​ · 2022 · ​ · 2023
Operating cash outflows from finance leases​$164​$183
Operating cash outflows from operating leases​$6,582​$10,709
Financing cash outflows from finance leases​$945​$1,055
​​​​​​​
Assets obtained in exchange for new finance lease liabilities (1)​$774​$1,569
ROU assets obtained in exchange for operating lease liabilities (1)​$13,449​$46,592
​ · ​ · ​ · ​ · ​
​December 31,December 31,
​ · ​ · 2022 · ​ · 2023
Weighted-average remaining lease term - finance leases2.34 years2.44 years
Weighted-average remaining lease term - operating leases11.29 years10.14 years
​ · ​ · ​ · ​ · ​
Weighted-average discount rate - finance leases5.71%7.41%
Weighted-average discount rate - operating leases8.44%9.82%
(1)These amounts are excluded from the accompanying consolidated statements of cash flows as they are non-cash investing, operating and/or financing activities.

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

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

Lessor Accounting

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

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

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

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

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

Note 17 —401(k) Plan

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

Note 18 —Net Loss Per Share

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

​​​​​​​​​​
​ · 2021 · 2022 · 2023
Net loss attributable to Clean Energy Fuels Corp.$(93,146)$(58,733)$(99,497)
​​​​​​​​​​
Weighted-average common shares outstanding​​213,118,694​​222,414,790​​222,904,785
Dilutive effect of potential common shares from restricted stock units, stock options and stock warrants​​—​​—​​—
Weighted-average common shares outstanding - diluted​​213,118,694​​222,414,790​​222,904,785
Basic loss per share​$(0.44)​$(0.26)​$(0.45)
Diluted loss per share​$(0.44)​$(0.26)​$(0.45)

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

​​​​​​​
(in shares) · 2021 · 2022 · 2023
Stock options17,153,67115,456,34017,825,577
Stonepeak warrant shares——20,000,000
Restricted stock units1,126,942694,945​399,709
Amazon warrant shares​58,767,714​58,767,714​58,767,714
Total​77,048,327​74,918,999​96,993,000

Note 19 —Related Party Transactions

TotalEnergies S.E.

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

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

SAFE&CEC S.r.l

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

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

TotalEnergies Joint Venture(s) and bpJV

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

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

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

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

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

Other Equity Method Investees

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

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

Note 20 —Reportable Segments and Geographic Information

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

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

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

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

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

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

Note 21 —Concentrations

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

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

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