Clean Energy Fuels Corp.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of

the Securities Exchange Act of 1934 (Amendment No. )

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Filed by a Party other than the Registrant☐

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CLEAN ENERGY FUELS CORP.

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

April 30, 2026

Dear Stockholder,

You are cordially invited to attend the annual meeting of stockholders (“Annual Meeting”) of Clean Energy Fuels Corp. (the “Company,” “Clean Energy,” “we,” “us” or “our”) on Wednesday, June 10, 2026, at 9:00 a.m. Pacific Time. The Annual Meeting will be a virtual meeting conducted via live audio webcast that can be accessed by visitingwww.virtualshareholdermeeting.com/CLNE2026. At this website, you will be able to listen to the Annual Meeting live, submit questions for our management, directors and representatives of our independent registered public accounting firm in attendance, and submit your vote while the Annual Meeting is being held.

I’m honored to be writing to you for the first time as Clean Energy’s chief executive officer. But I’m no stranger having been with the company for close to two decades. My goal as the incoming CEO is to focus on growing the company, using new technologies to find new customers and markets, engage with those customers, drive efficiencies and leverage the investments we’ve already made.

As we look back on 2025, it is clear that Clean Energy’s strategy and long-term investments continue to position us at the center of one of the most compelling transitions happening in transportation today. The momentum we’ve built across our renewable natural gas (“RNG”) production projects, fueling network, and customer base advanced significantly, and we closed 2025 stronger, more resilient, and more prepared for the growth ahead.

We now have eight dairy RNG projects in operation, along with three more in construction and development, each adding meaningful long term value to our RNG production portfolio. The completion of our South Fork Dairy project in Texas in 2025, now one of the largest RNG facilities in the country, was a huge milestone we crossed. South Fork is capable of producing 2.6 million gallons of low carbon-intensity transportation fuel annually, helping us continue to supply our network of stations and fleet customers.

The year also marked the successful monetization of $29.5 million in investment tax credits (“ITC”), the third ITC transaction tied to our RNG projects as part of our joint venture with bp. With this sale, all ITC credits across all six dairy RNG facilities have now been fully realized, reinforcing the value of these projects and strengthening the cash flow profile of our portfolio.

While our own RNG facilities continue to play an important role in supplying our network, they make up a portion of the fuel delivered across our stations. On the fuel supply side, we delivered 237 million gallons of RNG in 2025. To continue to support growing fleet demand, we draw from a broad, nationwide pool of producers, giving us access to diverse and reliable volumes of RNG from dairy, swine and landfill origins.

Our expansive fueling footprint remains an attractive outlet for RNG producers, as transportation use generates the strongest value for the fuel. As we grow, we remain disciplined in balancing the benefits of developing new projects with the flexibility that also comes from procuring RNG.

On the heavy duty trucking side of things, no segment of the transportation market is undergoing more rapid change, and 2025 was a milestone year on this front. The introduction of the Cummins X15N engine continued to energize the market.

Building on the success of our initial demonstration truck program from the year prior, we launched a second program featuring the Freightliner Cascadia tractor equipped with the X15N. Interest from fleets was strong, feedback and reviews are positive with many praising their firsthand experiences running heavy loads powered by RNG, while they continue to evaluate long-term alternatives to diesel. The combination of X15N performance and RNG’s carbon and cost advantages is resonating with major carriers nationwide.

We are also seeing rising demand across our transit and refuse customer base, who continue to adopt RNG not only as a means to decarbonize, but because it aligns with both budget and operational needs. In 2025, we secured more than a dozen new RNG supply agreements, adding over 10 million gallons of annual demand, while contracting 16 new stations and renewing long‑term supply at 17 existing locations. Combined, these commitments represent more than 30 million gallons of yearly fuel consumption and highlight the strength and staying power of our transit and refuse business.

As we look ahead, the opportunity in front of us is substantial. More fleets are acting now rather than waiting for alternative technologies that remain years from commercial viability. This aligns squarely with Clean Energy’s strategy: continue expanding our RNG supply, grow our customer base, and optimize the nation’s most extensive RNG fueling network. We are a unique company in that we provide a product to customers and to their customers that does good for the world. As I write this, traditional energy markets are being rocked by global events. But RNG is a domestic fuel that is not impacted by that. It also reduces harmful emissions, which we all care about.

Our development pipeline is active, our operational base is stronger than ever, and our ability to supply meaningful volumes of RNG, both produced and procured, is unmatched. With each new project, each new fleet deployment, and each gallon of RNG delivered, we strengthen our leadership position in the clean transportation market.

We are pleased to take advantage of laws and rules that allow issuers to make use of the Internet in conducting a meeting of stockholders, as well as in furnishing proxy materials. As a result, we will not only host the Annual Meeting virtually on the Internet, but we will also furnish the proxy materials for the Annual Meeting to our stockholders on the Internet. We believe this use of the Internet meaningfully lowers our costs, increases efficiencies and helps reduce the environmental impact of the Annual Meeting, while permitting and encouraging increased stockholder attendance and engagement.

The accompanying notice of Annual Meeting and Proxy Statement include the agenda for the Annual Meeting, explain the matters that will be discussed and voted on at the Annual Meeting and provide certain other information about our Company.

Your vote is important, and we urge you to vote as promptly as possible. Thank you for supporting our Company.

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

June 10, 2026

The annual meeting of stockholders (“Annual Meeting”) of Clean Energy Fuels Corp. (the “Company,” “we,” “us” or “our”) will be held on Wednesday, June 10, 2026, at 9:00 a.m. Pacific Time via live audio webcast that can be accessed by visitingwww.virtualshareholdermeeting.com/CLNE2026, for the following purposes:

The foregoing items of business are more fully described in the Proxy Statement that accompanies this notice.

The Company’s Board of Directors has fixed the close of business on April 16, 2026 as the record date for the determination of stockholders entitled to notice of and to vote at the Annual Meeting and any adjournment or postponement thereof. A list of stockholders entitled to vote at the Annual Meeting will be available for inspection by any stockholder for any purpose germane to the Annual Meeting at our principal executive offices during normal business hours for a period of 10 days before the Annual Meeting. The list of stockholders may also be accessed during the virtual Annual Meeting atwww.virtualshareholdermeeting.com/CLNE2026 by using the control number on your proxy card, voting instruction form or Notice of Internet Availability.

Even if you plan to attend the Annual Meeting, you are encouraged to vote on the Internet, by telephone or by mail before the Annual Meeting using the instructions provided in the accompanying proxy materials to ensure that your vote will be counted. If you submit your proxy or voting instructions and then decide to attend the Annual Meeting, you may still vote your shares during the Annual Meeting.

2026 PROXY STATEMENT