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 (Amendment No.  1)

Filed by the Registrant  ☒                            Filed by a Party other than the Registrant  ☐

Check the appropriate box:)

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 the appropriate box):

CLEAN ENERGY FUELS CORP.

4675 MacArthur Court, Suite 800

Newport Beach, California 92660

IMPORTANT INFORMATION AND SUPPLEMENTAL MATERIALS FOR 2018 ANNUAL MEETING

May [    ], 2018April  , 2021

Dear Stockholder,

We

You are writingcordially invited to notify you of important information aboutattend the 2018 annual meeting of stockholders (“Annual Meeting”) of Clean Energy Fuels Corp. (the “Company,” “Clean Energy,” “we,” “us” or “our”).

On or about April 20, 2018, we furnished to you our proxy materials for the Annual Meeting, including a proxy statement that describes proposals to be voted on at the Annual Meeting. Subsequently, we have determined to postpone the date of the Annual Meeting, from Wednesday, May 30, 2018Monday, June 14, 2021, at 9:00 a.m. Pacific Time to Friday, June 8, 2018 at 9:00 a.m. Pacific Time, and to add new proposals to be voted on at the Annual Meeting. Accordingly, we are furnishing to you, together with this letter, an updated notice of the Annual Meeting and a supplement to the previously furnished proxy statement for the Annual Meeting, which reflect the revised agenda for the Annual Meeting and describe the new proposals to be voted on at the Annual Meeting, as well as a new proxy card for purposes of casting your vote on all of the proposals to be voted on at the Annual Meeting.Time. The Annual Meeting will remainbe a virtual meeting conducted via live audio webcast that can be accessed on the new date ofby visiting www.virtualshareholdermeeting.com/CLNE2021. At this website, you will be able to listen to the Annual Meeting by visitingwww.virtualshareholdermeeting.com/CLNE2018.

We are postponing the datelive, 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 to provideis being held.

We are excited about the Annual Meeting, particularly because it provides our stockholders an opportunity to approve a transactioncomponent of what we believe could be pivotal and transformativeis an important commercial partnership for our Company.Clean Energy. On May 9, 2018,April 16, 2021, in connection with entering into a Project Addendum to Fuel Pricing Agreement (the “Fuel Agreement”) with a subsidiary of Amazon.com, Inc. (“Amazon”), we entered into a definitive agreementTransaction Agreement with Total Marketing Services S.A., a wholly ownedAmazon under which we issued to another subsidiary of Total S.A. (“Total”Amazon a warrant (the “Amazon Warrant”), pursuant to which we agreed to sell and issue, and Total agreed to purchase up to 50,856,296an aggregate of 53,141,755 shares of our common stock at a purchasean exercise price of $1.64$13.49 per share, which would result in gross proceeds to us of up to $83.4 million. If this transaction is completed, Total would hold up to 25.0% ofwas 21.3% more than the outstanding shares$11.12 closing price of our common stock. Our Boardstock on April 15, 2021.

Through the Fuel Agreement and Amazon Warrant, our board of Directorsdirectors (the “Board”) believes Amazon can become an important strategic partner for Clean Energy. Further, Amazon is purchasing low and negative carbon Renewable Natural Gas (“Board”RNG”) has whole-heartedlyfrom Clean Energy, which we believe validates using RNG as a transportation fuel at scale.

We expect to provide RNG to Amazon through 27 existing fueling stations and unanimously approved this transaction, and all Board members and senior executive officers (including myself and Boone Pickens) have agreed19 non-exclusive new or upgraded stations that we expect to vote our shares in favorconstruct by the end of the transaction. year. The new and existing stations will provide RNG in 15 different states across the United States, and we will own all the stations.

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 million, excluding any payments attributable to “Pass Through Costs,” which consist all costs associated with the delivered cost of gas and applicable taxes determined by reference to the selling price, gallons or gas sold. Importantly, if all the vesting conditions of the Amazon Warrant are satisfied, Amazon will have purchased hundreds of millions of gasoline gallon equivalents (“GGEs”) of RNG at today’s fuel prices from Clean Energy.

We believe Total is a valuable strategic investorcommercial partnership with Amazon will enhance our strategies, initiatives and partnerefforts to achieve our goals to grow fleet and other consumer support for our Company. Total, headquartered in Paris, France, is onethe use of the largest major global natural gas and energy organizations, and has been a leading force behind clean energy initiatives. Also, and importantly, Total has enthusiastically embraced natural gasRNG as a vehicle fuel. We believe a partnership with Total validatesfuel for our strategiestarget customers and key initiatives and provides a catalyst for future growth.geographies. The Board also believes the proceeds from the saleissuance of our common stock to Total willAmazon in the event Amazon were to vest and then exercise the Amazon Warrant in part or whole for cash, would enhance our liquidity in support of our operations, as well as our ability to execute our business plans and pursue opportunities for further growth,growth. Accordingly, we believe securing this commercial partnership and incenting Amazon to purchase the maximum amount of fuel under the Fuel Agreement is important for the trajectory of Clean Energy.

Our Board approved the Fuel Agreement and Amazon Warrant, and recommends our abilitystockholders approve the Amazon Warrant as described in these proxy materials. Further, all independent Board members and senior executive officers (including myself) have agreed to satisfyvote our commitments (including repaymentsshares in favor of the transaction.

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 outstanding debt). Further, we have signed a letter of intent with Total for another, separate transaction, which would involvestockholders on the launch of an innovative truck leasing program and up to $100 million of credit support from Total.Internet. We believe this truck leasing program could play a critical role in generatinguse of the Internet meaningfully lowers our costs, increases efficiencies and helps reduce the environmental impact of the Annual Meeting, while permitting and encouraging increased adoptionstockholder attendance and engagement.

The accompanying notice of natural gas as a vehicle fuel in the U.S. heavy-duty truck market, which is a key customer market for our business.

Because the accompanyingAnnual Meeting and proxy statement supplement describes new proposals toinclude the agenda for the Annual Meeting, explain the matters that will be discussed and voted on at the Annual Meeting that were not described in the proxy materials previously furnished to you, all proxies submitted before the date of the supplement will not include votes on these new proposals.As a result, if you want to vote on the new proposals described in the accompanying proxy statement supplement, you must cast a new vote for the Annual Meeting. New votes may be cast on the Internet, by telephone or by completing and returning a pink proxy card, which replaces any white proxy card you may have previously received for purposes of voting at the Annual Meeting.provide certain other information about our Company.

Your vote is important, and we urge you to vote as promptly as possible. If you have questions about the Annual Meeting or need assistance in voting your shares, please contact our proxy solicitor, MacKenzie Partners, Inc., using the following contact information:

MacKenzie Partners, Inc.

1407 Broadway, 27^th Floor

New York, NY 10018

(212) 929-5500 or

Call Toll Free (800) 322-2885

Email: proxy@mackenziepartners.com

	Sincerely,
Sincerely,
ANDREW J. LITTLEFAIR
	President & Chief Executive Officer and Director

effect as of the date hereof (“Restated Certificate”), to increase the number of shares of our common stock we are authorized to issue by approximately 35.7%; (6) the approval of an amendment to the Restated Certificate to effect, on or before May 31, 2019, a reverse split of our authorized, issued and outstanding common stock, at a ratio of between1-for-5 and1-for-10 and if and when and at such ratio as may be determined by our Board or an authorized committee thereof (the “Reverse Stock Split”); (7) the approval of the adjournment of the Annual Meeting if necessary or advisable to permit further solicitation of proxies in the event there are not sufficient votes at the time of the Annual Meeting to approve any or all of the foregoing proposals; and such other business as may properly come before the Annual Meeting. This Supplement and the Proxy Statement, taken together, summarizesummarizes the information you need to know in order to vote on these proposals in an informed manner.

This Supplement only relates to certain

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS

The Notice of the proposals to be voted on by stockholders at the Annual Meeting, Proxy Statement and as a result, it does not containour Annual Report are available at www.proxyvote.com. You are encouraged to access and review all of the information that is important to your decisions with respect to voting on all of the proposals that will be presented to stockholders at the Annual Meeting. Additional information is contained in the Proxy Statement as it was previously filed with the SEC and furnished to our stockholders. To the extent the information in this Supplement differs from, updates or conflicts with the information contained in the Proxy Statement, the information in this Supplement shall amend and supersede the information containedour proxy materials before voting. Copies of these proxy materials are also available in the Proxy Statement. Except as so amended or superseded, all information set forth in the Proxy Statement remains unchangedInvestors—Annual Reports and important for you to review. Accordingly, we urge you to read this Supplement carefully and in its entirety and together with the Proxy Statement.

CERTAIN INFORMATION ABOUT THIS SUPPLEMENT AND THE ANNUAL MEETING

This Supplement describes Proposals 4, 5, 6 and 7, which are new proposals being added to the agenda for the Annual Meeting and therefore are not described in the Proxy Statement. Information about Proposals 1, 2 and 3, each of which will also be presented to stockholders at the Annual Meeting, can be found in the Proxy Statement as originally filed with the SEC and first sent or given to our stockholders on April 20, 2018.

Delivery of Proxy Materials

MostProxies section of our stockholders who are entitled to notice of and to votewebsite at the Annual Meeting previously received a noticewww.cleanenergyfuels.com.

Use of the availability ofInternet

Pursuant to rules adopted by the SEC, we have elected to provide access to our proxy materials for the Annual Meeting, including this Proxy Statement and our Annual Report, on the Internet. Accordingly, on or about April , 2021, we are mailing a Notice of Internet which providedAvailability of Proxy Materials (“Notice”) to all of the Company’s stockholders of record who have not previously elected an alternative delivery method, while brokers, banks and other nominees who hold shares on behalf of beneficial owners will be sending their own similar Notice to the beneficial owners. The Notice will include instructions on how toyou may access thesethe proxy materials for the Annual Meeting at www.proxyvote.com. For stockholders who have previously elected to receive copies of the proxy materials by mail or e-mail, we will be sending the Annual Report, this Proxy Statement and a proxy card by that method on the Internet, but didor about April , 2021. Stockholders who receive a Notice will not receive printed copies of the proxy materials unless they requested them. For purposes of the supplemental proxy materials we are providing because of the changes tofor the Annual Meeting unless they request them, in which case printed copies of the proxy materials and a paper proxy card will be provided at no charge. Any stockholder may request to receive the Proxy Statement as describedproxy materials for the Annual Meeting in this Supplement,printed form by mail or electronically by e-mail on an ongoing basis until the one-year anniversary of the date of the Annual Meeting by following the instructions in the Notice. We encourage you to take advantage of the availability of our proxy materials on the Internet in order to lower our printing and delivery costs and help reduce the environmental impact of the Annual Meeting.

We have held our annual meetings of stockholders virtually since 2017, and we have again elected to providehold this year’s Annual Meeting virtually on the Internet. We have made this decision for a number of reasons, including:

Stockholders who choose to these supplemental materials, including this Supplement,attend the Updated NoticeAnnual Meeting will do so by accessing a live audio webcast of the Annual Meeting via the Internet at www.virtualshareholdermeeting.com/CLNE2021. Please see “Attending the Virtual Annual Meeting” below for more information.

Record Date and a proxy card reflectingOutstanding Shares

All stockholders that owned shares of our common stock at the close of business on April 19, 2021, the date fixed by the Board as the record date, are entitled to vote at the Annual Meeting.

On the record date, 199,857,559 shares of our common stock were outstanding.

Voting Matters

Voting Rights

Each share of our common stock entitles the owner of the share to one vote on all seven proposalsmatters to be voted on at the Annual Meeting.

Quorum Requirement

We will have the required quorum to conduct the business of the Annual Meeting bothif holders as of the record date representing a majority of the outstanding shares of our common stock entitled to vote are present in person or represented by mailing (or,proxy at the Annual Meeting. Abstentions and broker non-votes (discussed under “Effect of Not Providing Voting Instructions; Broker Non-Votes” below) will be counted for purposes of determining the presence of a quorum at the Annual Meeting.

Effect of Not Providing Voting Instructions; Broker Non-Votes

Stockholders of Record. You are a “stockholder of record” if your shares are registered directly in your name with Computershare Trust Company, N.A., our transfer agent. If you were a stockholder of record at the close of business on the record date for the Annual Meeting and you submit a valid proxy but do not provide voting instructions with respect to your shares, all shares represented by your proxy will be voted in accordance with the recommendation of our Board on each proposal to be presented at the Annual Meeting, as described in this Proxy Statement.

Beneficial Owners of Shares Held in Street Name. You are a “beneficial owner of shares held in street name” if your shares are not held of record in your name but are held by a broker, bank or other nominee on your behalf as the beneficial owner. Pursuant to applicable stock exchange rules, if your shares were held in street name through a brokerage account at the close of business on the record date for the Annual Meeting, you must provide voting instructions to your broker if you have previously consentedwant your shares to electronic delivery, emailing) to you a full setbe voted on the election of these supplemental materials, and also by notifying youdirectors (Proposal 1), the approval, on an advisory, non-binding basis, of the availabilitycompensation of our named executive officers (Proposal 3), and the approval, for the purpose of complying with Nasdaq Listing Rule 5635(b), of the issuance of shares of our common stock upon exercise of the Amazon Warrant (Proposal 4). These proposals constitute “non-routine” matters on which a broker is not entitled to vote shares held for a beneficial owner without receiving voting instructions from the beneficial owner. The ratification of the appointment of KPMG LLP as our independent registered public accounting firm (Proposal 2) and the approval of an amendment to our Restated Certificate of Incorporation to increase the authorized shares of our common stock (Proposal 5) are considered “routine” matters for which your shares may be voted in the discretion of your broker if voting instructions have not been received. As a result, if you hold your shares in street name and you do not submit voting instructions to your broker, your broker may exercise its discretion to vote on Proposal 2 and Proposal 5 at the Annual Meeting but will not be permitted to vote on Proposal 1, Proposal 3 or Proposal 4 at the Annual Meeting. If your broker exercises this discretion, your shares will be counted as present for determining the presence of a quorum at the Annual Meeting and will be voted on Proposal 2 and Proposal 5 in the manner directed by your broker, but your shares will constitute “broker non-votes” on each of the other items at the Annual Meeting. Moreover, if you are a beneficial owner of shares in street name and you properly submit a voting instruction form to your broker, bank or other nominee that is signed but unmarked with respect to your vote on Proposals 1, 2, 3, 4 or 5, applicable rules will generally permit your broker, bank or other nominee to vote your shares on these proposals in accordance with the recommendations of the Board as set forth in this Proxy Statement.

Voting Requirements

The election of directors (Proposal 1) will be determined by a plurality of the votes cast on the Internetproposal at the Annual Meeting. This means that the nine nominees who receive the highest number of allaffirmative votes will be elected as directors. Shares voted “Withhold” and broker non-votes are not counted as votes cast and will have no effect on the outcome of the election of directors.

The ratification of the appointment of KPMG LLP as our independent registered public accounting firm (Proposal 2), the approval, on an advisory, non-binding basis, of the compensation of our proxy materials, including these supplemental materialsnamed executive officers (Proposal 3), and the Proxy Statement and our Annual Reportapproval, for the year ended December 31, 2017. Accordingly,purpose of complying with Nasdaq Listing Rule 5635(b), of the issuance of shares of our common stock upon exercise of the Amazon Warrant (Proposal 4) must each be approved by the affirmative vote of a majority of the votes cast on the proposal at the Annual Meeting. For purposes of determining the number of votes cast for Proposals 2, 3 and pursuant4, only shares voted “FOR” or “AGAINST” are counted. Abstentions and broker non-votes are not treated as votes cast and will not be counted in determining the outcome of Proposal 2, 3 or Proposal 4.

The approval of an amendment to applicable SEC rules that require usour Restated Certificate of Incorporation to notifyincrease the authorized shares of our common stock (Proposal 5) must be approved by the affirmative vote of the holders of a majority of the issued and outstanding shares of our common stock entitled to vote on the proposal at the Annual Meeting. Abstentions will have the same effect as a vote against Proposal 5. Because Proposal 5 is expected to be a “routine” matter for which you shares may be voted in the discretion of your broker if voting instructions have not been received, we do not expect any broker non-votes to occur on Proposal 5.

The following is a summary of the voting requirements for each proposal to be voted on at the Annual Meeting:

Tabulation of Votes

The inspector of elections of the Annual Meeting will tabulate the votes of our stockholders ofat the availability of allAnnual Meeting. All shares of our common stock represented by proxy materialsat the Annual Meeting will be voted in accordance with the instructions given on the Internet, we are providingproxy, as long as the following notice:proxy is properly submitted and unrevoked and is received by the applicable deadline, all as described under “How to Cast or Revoke Your Vote” below. If the Annual Meeting is adjourned or postponed, properly submitted and unrevoked proxies will remain effective and will be voted at the adjourned or postponed Annual Meeting, and stockholders will retain the right to revoke any such proxy until it is actually voted at the adjourned or postponed Annual Meeting.

Important Notice Regarding

Voting Results

Preliminary results will be announced at the Availability of Proxy Materials

for the Stockholder MeetingAnnual Meeting. Final results will be reported in a current report on Form 8-K to be held on Friday, June 8, 2018

The Proxy Statement, Supplement andfiled with the SEC within four business days after the Annual ReportMeeting concludes. If the official results are not available at that time, we will provide preliminary voting results in such a Form 8-K and will provide the final results in an amendment to the Form 8-K as soon as they become available.

www.proxyvote.com

How to Cast or Revoke Your Vote

Because this Supplement describes new proposals to be voted on at the Annual Meeting that were not reflected or described in the Proxy Statement, proxies submitted before the date of this Supplement will not include votes on these new proposals.As a result, if you want to vote on the new proposals described in this Supplement, you must cast a new vote for the Annual Meeting.New votes may be cast or revoked, and previously submitted votes may be revoked andre-cast, as described below. Your vote is important, and we urge you to vote as promptly as possible.

Stockholders of Record

If you are a stockholder of record entitled to vote at the Annual Meeting, you may vote in any one of the following ways:

Votes submitted by proxy on the Internet or by telephone must be received by 11:59 p.m. Eastern Time on Thursday,Sunday, June 7, 201813, 2021 to be counted. Votes submitted on the Internet during the Annual Meeting by stockholders attending the meeting and votes submitted by mail must be received no later than the close of voting at the Annual Meeting to be counted.

Once you have submitted your proxy on the Internet or by telephone or mail, including proxies submitted before or after the date of this Supplement, you may revoke it at any time before it is voted at the Annual Meeting by taking any one of the following actions:

To be effective, any later-dated vote must be received by the applicable deadline for the voting method used, as described above, and any written notice of revocation must be received no later than the close of voting at the Annual Meeting. Only your latest-dated vote that is received by the deadline applicable to the voting method used will be counted.

Beneficial Owners of Shares Held in Street Name

If you are a beneficial owner of shares held in “street name” (that is, through a broker, bank or other nominee),street name, you have the right to instruct your broker, bank or other nominee on how to vote your shares at the Annual Meeting. You should do so by following the instructions provided by your broker, bank or other nominee regarding how to vote your shares and how to revoke a previously submitted proxy. The availability of Internet, telephone or other methods to vote your shares by proxy, and the deadlines by which to vote your shares using each such voting method, will depend on the voting processes of the broker, bank or other nominee that holds your shares.

Forward-Looking Statements

All stockholders that owned our common stock at the close of business on the record date for the Annual Meeting, or their duly appointed proxies, may attend and participate in the Annual Meeting. 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, to ensure that your vote will be counted. Please see “How to Cast or Revoke Your Vote” above.

To attend and participate in the Annual Meeting, stockholders will need to access the live audio webcast of the meeting. To do so, stockholders of record will need to visit www.virtualshareholdermeeting.com/CLNE2021 and use their 16-digit control number provided in the Notice to log in to this website, and beneficial owners of shares held in street name will need to follow the instructions provided by the broker, bank or other nominee that holds their shares. On the day of the Annual Meeting, stockholders may begin to log in to the virtual meeting beginning at 8:45am PT, and the meeting will begin promptly at 9:00am PT. We encourage stockholders to log in to this website and access the webcast before the Annual Meeting’s start time. Further instructions on how to attend, participate in and vote at the Annual Meeting are available at www.proxyvote.com. If you encounter any difficulties accessing or logging in to the Annual Meeting, including any difficulties with your control number or submitting questions, please call the technical support number displayed on the login page on the online virtual meeting platform.

Submitting your proxy before the Annual Meeting will not affect your right to vote at the Annual Meeting if you decide to attend; however, your attendance at the Annual Meeting after having submitted a valid proxy will not in and of itself constitute a revocation of your proxy. To revoke a previously submitted proxy by attending that Annual Meeting, you must submit an online vote during the webcast of the Annual Meeting reflecting your new vote.

Solicitation

This Supplement contains forward-looking statementssolicitation is made by our Board, and we will bear the entire cost of soliciting proxies, including the costs of preparing, printing, assembling and mailing the Notice, any printed copies of this Proxy Statement, the proxy card, the Annual Report or our other proxy materials that may be requested by stockholders, and any additional information that we may elect to furnish to stockholders. We will provide copies of solicitation materials to brokers, banks and other nominees holding in their names shares of our common stock that are beneficially owned by others for forwarding to the beneficial owners of those shares who have requested printed materials, and we may reimburse persons representing beneficial owners for their costs of forwarding solicitation materials to the beneficial owners. Solicitations will be made primarily through the Notice and the solicitation materials made available on the Internet or via e-mail or in print to those who request copies, but may be supplemented by telephone, mail, e-mail or personal solicitation by our directors, executive officers or other employees. We will pay no additional compensation to these individuals for these activities. We have not engaged employees for the specific purpose of soliciting proxies. The Board’s solicitation will also be made by MacKenzie Partners, Inc. (“MacKenzie”), which we have retained to assist with the distribution of our proxy materials, the solicitation of proxies, and the tabulation of votes for the Annual Meeting.

We will bear all costs related to this solicitation, including the costs of preparing, printing, assembling, mailing or otherwise furnishing our proxy materials to our stockholders, reimbursement of persons representing beneficial owners for their costs of forwarding such proxy materials to the beneficial owners, and the fees and expenses of MacKenzie in connection with its proxy solicitation services for the Annual Meeting. Pursuant to our arrangement with MacKenzie, we have agreed to pay MacKenzie for these services a base fee of $25,000, plus additional per-service fees for specified services if needed or requested and reimbursement of MacKenzie’s reasonable out-of-pocket expenses.

Separate Copy of Annual Report or Other Proxy Materials

We have adopted a procedure called “householding,” which the SEC has approved. Under this procedure, we are delivering a single copy of this Proxy Statement and our Annual Report to multiple stockholders who share the same address and who did not receive a Notice or otherwise receive their proxy materials by e-mail, unless we have received contrary instructions from a stockholder. This procedure reduces our printing and mailing costs and other fees. Stockholders who participate in householding will continue to be able to request and receive a separate Notice or proxy card. Additionally, upon written or oral request, we will deliver promptly a separate copy of this Proxy Statement or the Annual Report to any stockholder at a shared address to which we have delivered a single copy of these documents. To receive a separate copy of this Proxy Statement or the Annual Report, or to notify us that you wish to receive separate copies of our proxy materials for future annual meetings of our stockholders, write to the attention of Investor Relations at the address of our principal executive offices or call (949) 437-1000. Stockholders who share an address and are receiving multiple copies of our proxy materials may also request to receive a single copy of this Proxy Statement and the Annual Report or our proxy materials for future annual meetings of our stockholders by writing or calling us at the address or telephone number provided above.

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The two tables below show the beneficial ownership of certain persons with respect to our common stock, our only outstanding class of voting securities. Except as indicated by the footnotes to these tables, we believe, based on the information furnished or otherwise available to us, that the persons and entities named in these tables have sole voting and investment power with respect to all shares of common stock shown as beneficially owned by them, subject to applicable community property laws.

We have determined beneficial ownership as shown in these tables in accordance with the rules of the SEC. In accordance with these rules, in computing the number of shares of our common stock beneficially owned by a person and the percentage ownership of that person, we deemed to be outstanding all shares of our common stock subject to (1) stock options held by that person that are currently exercisable or exercisable within 60 days after April 19, 2021, and (2) restricted stock units (“RSUs”) held by that person that are subject to vesting and settlement within 60 days after April  19, 2021. We did not, however, deem these shares outstanding for the purpose of computing the percentage ownership of any other person. We calculated percentage ownership as shown in these tables based on 199,857,559 shares of our common stock outstanding on April 19, 2021. The information in these tables is not necessarily indicative of beneficial ownership for any other purpose, and the inclusion of any shares in these tables does not constitute an admission of beneficial ownership of the shares.

The following table shows the amount and percentage of our common stock beneficially owned by each holder of more than 5% of the outstanding shares of our common stock:

(1)   Based on a Schedule 13D/A filed by TOTAL S.E. (“TOTAL”) and its direct wholly owned subsidiary Total Marketing Services S.A. (“TMS”) on June 14, 2018 that reflects shares of common stock beneficially owned as of June 13, 2018. The shares of common stock beneficially owned consist of (i) 50,856,296 shares of common stock that were purchased from us by TMS and (ii) 7,898,021 shares of common stock that are the subject of a voting agreement, dated May 9, 2018, among TMS, the company, and all of our then-directors and officers, pursuant to which each such director and officer appointed TMS as such person’s proxy and attorney-in-fact, and authorized TMS to represent and vote (or consent, if applicable) all shares of common stock owned or controlled by such person with respect to the election of the individuals designated by TMS to serve on our Board pursuant to TMS’ director designation rights (described below under “Certain Relationships and Related Party Transactions”). TOTAL and TMS have expressly disclaimed beneficial ownership of any shares of common stock subject to the voting agreement discussed in (ii) above.

(2)   Based on a Schedule 13G/A filed by Dimensional Fund Advisors LP on February 12, 2021 that reflects shares of common stock beneficially owned as of December 31, 2020. According to the Schedule 13G/A, Dimensional Fund Advisors LP has sole voting power with respect to 10,446,603 shares of our common stock and sole dispositive power with respect to 11,013,905 shares of our common stock. Dimensional Fund Advisors LP, an investment adviser registered under Section 203 of the Investment Advisors Act of 1940, furnishes investment advice to four investment companies registered under the Investment Company Act of 1940, and serves as investment manager or sub-adviser to certain other commingled funds, group trusts and separate accounts (such investment companies, trusts and accounts, collectively referred to as the “Funds”). In certain cases, subsidiaries of Dimensional Fund Advisors LP may act as an adviser or sub-adviser to certain Funds. In its role as investment advisor, sub-adviser and/or manager, Dimensional Fund Advisors LP or its subsidiaries (collectively, “Dimensional”) may possess voting and/or investment power over shares of our common stock that are owned by the Funds and may be deemed to be the beneficial owner of shares of our common stock held by the Funds. However, all shares of our common stock reported in the table above are owned by the Funds. Dimensional disclaims beneficial ownership of such securities.

The following table shows the amount and percentage of our common stock beneficially owned on April 19, 2021 by each of our named executive officers and current and nominated directors and by all of our current executive officers and directors as a group:

*      Represents less than 1%.

(1)   Beneficial ownership consists of (a) 987,431 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021, and (b) 1,363,582 shares of outstanding common stock held directly.

(2)   Beneficial ownership consists of (a) 453,479 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021, and (b) 329,332 shares of outstanding common stock held directly.

(3)   Beneficial ownership consists of (a) 438,297 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021 and held directly or by the Pratt Family Trust, over which Mr. Pratt possesses sole voting and investment control, and (b) 617,837 shares of outstanding common stock held directly or by the Pratt Family Trust.

(4)   Beneficial ownership consists of (a) 485,324 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021, and (b) 550,415 shares of outstanding common stock held directly or by an individual retirement account for the benefit of Mr. Corbus.

(5)   Beneficial ownership consists of (a) 22,000 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021; and (b) 30,000 shares of outstanding common stock held directly.

(6)   Beneficial ownership consists of (a) 209,500 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021, and (b) 131,001 shares of outstanding common stock held directly or by a trust over which Mr. Miller possesses shared voting and investment control.

(7)   Beneficial ownership consists of (a) 164,500 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021, and (b) 199,118 shares of outstanding common stock held by the Scully Family Trust, over which Mr. Scully possesses sole voting and investment control.

(8) Beneficial ownership consists of (a) 169,500 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021, (b) 30 shares of outstanding common stock held in a Uniform Transfers to Minors Act account for which Mr. Socha is the custodian and over which Mr. Socha possesses sole voting and investment control, and (c) 229,728 shares of outstanding common stock held directly.

(9) Beneficial ownership consists of (a) 209,500 shares of common stock subject to options currently exercisable or exercisable within 60 days after April 19, 2021, and (b) 287,018 shares of outstanding common stock held by the Vincent C. Taormina REV Intervivos Trust UAD 5/14/84, over which Mr. Taormina possesses sole voting and investment control.

(10) Beneficial ownership consists of 42,000 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021.

(11) Beneficial ownership consists of (a) 3,181,531 shares of common stock subject to stock options currently exercisable or exercisable within 60 days after April 19, 2021, and (b) 3,738,061 shares of outstanding common stock held directly by our executive officers and directors, by individual retirement accounts for the benefit of a director or executive officer, or by trusts or a Uniform Transfers to Minors Act account over which an executive officer or director possesses voting and investment control.

PROPOSAL 1

ELECTION OF DIRECTORS

General

Our Board, acting pursuant to our amended and restated bylaws, has determined that the number of directors constituting the full Board is to be ten. Following the resignation of John Herrington from the Board effective March 12, 2021, the number of directors on the Board is currently nine, leaving one vacancy; we expect the vacancy to be filled during 2021 in furtherance of our director refreshment. Upon the recommendation of our nominating and corporate governance committee, the Board nominated Andrew J. Littlefair, Stephen A. Scully, Lizabeth Ardisana, Philippe Charleux, Thomas Maurisse, James C. Miller III, Kenneth M. Socha, Vincent C. Taormina, and Parker Weil for election as members of the Board at the Annual Meeting. Each of our director nominees other than Messrs. Charleux, Littlefair, and Maurisse are independent directors within the meaning of Section 27Aapplicable rules of Nasdaq. You are being asked to vote on the election of each of these nine director nominees. At the Annual Meeting, proxies cannot be voted for a greater number of individuals than the nine nominees named in this Proxy Statement.

Each of the Securities Actnominees is a director of 1933,our Company and, except for Messrs. Maurisse and Weil, was elected by our stockholders at our 2020 annual meeting of stockholders. Mr. Weil was appointed as amended (“Securities Act”)a director in June 2020 after being initially recommended for appointment to the Board by Mr. Littlefair. Mr. Maurisse was appointed as a director in February 2021 and is being nominated for election at the Annual Meeting, pursuant to director designation rights granted to TMS in June 2018. Mr. Charleux, a director initially appointed to the Board in February 2020 and elected by our stockholders at our 2020 annual meeting of stockholders, is also being nominated for election at the Annual Meeting pursuant to the director designation rights granted to TMS in 2018. See “Certain Relationships and Related Party Transactions” below for further information about the director designation rights granted to TMS.

Upon election at the Annual Meeting, each director will serve a one-year term until the next annual meeting of our stockholders and until his or her respective successor is duly elected and qualified or until his or her earlier resignation or removal. Each of the Board’s director nominees has agreed to serve if elected, and, as of the date of this Proxy Statement, we have no reason to believe any nominee will be unable or unwilling to serve as a director if elected. If, however, any nominee is unable to serve, or for good cause will not serve, as a director at the time of the Annual Meeting, the persons who are designated as proxies may vote your shares, in their discretion, for another nominee that may be proposed by the Board or the Board may choose to reduce the size of the Board.

We, as a matter of policy, encourage our directors to attend meetings of our stockholders and, in 2020, all of our then-current directors attended our annual meeting.

Director Nominees

The names of the director nominees, their ages as of the date of this Proxy Statement, their current positions and offices with our Company and other information about their professional backgrounds are shown below. We believe each of these nominees contributes to the Board’s effectiveness as a whole based on the wealth of executive leadership experience they bring to the Board, as well as the other specific attributes, qualifications and skills described below. There are no family relationships between any director, executive officer or person nominated or chosen to become a director or executive officer of our Company, and except as described under “General” above with respect to Messrs. Charleux and Maurisse, there are no arrangements or understandings between any director or nominee and any other person pursuant to which such individual was or is selected as a director or nominee.

Andrew J. Littlefair, one of our founders, has served as our President, Chief Executive Officer and a director since June 2001. From 1996 to 2001, Mr. Littlefair served as President of Pickens Fuel Corp., and Section 21Efrom 1987 to 1996, Mr. Littlefair served in various management positions at Mesa, Inc., an energy company. From 1983 to 1987, Mr. Littlefair served in the Reagan Administration as a Staff Assistant to the President. Mr. Littlefair served as Chairman of NGV America, the leading U.S. advocacy group for natural gas vehicles, from March 1993 to March 2011. Mr. Littlefair has served on the board of directors of Hilltop Holdings Inc. (formerly PlainsCapital Corporation), a reporting company under the Securities Exchange Act of 1934, as amended (“Exchange Act”). Forward-looking statements are statements, since 2009. Mr. Littlefair earned a B.A. from the University of Southern California.

Mr. Littlefair brings to our Board his experience as a co-founder and the Chief Executive Officer of our Company, which gives him unique insight into our Company’s operations, challenges and opportunities.

Stephen A. Scully has served as a director of our Company since January 2014 and was appointed as Chairman of the Board on January 1, 2018. Mr. Scully was founder and President of the Scully Companies, a California-based truck leasing and specialized contract carriage provider. He started the Scully Companies immediately after graduating from the University of Southern California in 1981 and subsequently sold it to Ryder System in January 2011. The Scully Companies was the largest independent asset-based logistics provider in the western United States. Since selling the Scully Companies, Mr. Scully has been a private investor. Additionally, he was the Chairman of the Board of the National Truck Leasing System from 1999 to 2010, a board member of the Truck Rental and Leasing Association from 1990 to 1999, a board member of Ameriquest Transportation and Logistics Resources from 2007 to 2008 and is a former member of the California Trucking Association.

Mr. Scully brings to our Board the insight of a successful entrepreneur and operator, as well as extensive knowledge of the trucking industry.

Lizabeth Ardisana has served as a director of our Company since December 2019. Ms. Ardisana is the chief executive officer and the principal owner of the firm ASG Renaissance, LLC, which she founded in 1987. ASG Renaissance is a technical and communication services firm with experience providing services to clients in the automotive, environmental, defense, construction, healthcare, banking, and education sectors. Ms. Ardisana is also chief executive officer of Performance Driven Workforce, LLC, a scheduling and staffing firm that was founded in 2015 and has since expanded into five states. Ms. Ardisana, a Hispanic and female business owner, is an active business and civic leader in Michigan. Ms. Ardisana has held numerous leadership positions in a variety of non-profit organizations, including the United Way for Southeastern Michigan (where she serves as chair), Skillman Foundation, CS Mott Foundation, Kettering University, Metropolitan Affairs Coalition and Focus: Hope. She was appointed by the governor of Michigan to the executive board of the Michigan Economic Development Corporation and serves on its finance committee. Ms. Ardisana is also vice chair of the Wayne State University Physicians Group where she serves on the audit committee. She holds a bachelor’s degree in Mathematics and Computer Science from the University of Texas, a master’s degree in Mechanical Engineering from the University of Michigan and a master’s degree in Business Administration from the University of Detroit. Ms. Ardisana has been a member of the board of directors of Huntington Bancshares Inc. since 2016 and was a member of the board of directors of FirstMerit Corporation from 2013 to 2016.

Ms. Ardisana brings to our Board key experience and relationships in the automotive and environmental industries, as well as skills acquired through serving as a chief executive officer and as a member of multiple public and private company boards.

Philippe Charleux has served as a director of our Company since February 2020. Since 2017, Mr. Charleux has been Senior Vice-President Lubricants and Specialties of TMS; he is also a member of Total’s Group Performance Management Committee.  Mr. Charleux began his career with Total in 1986 as a research engineer, and in 1991, he became a process model engineer in the Refining Division. From 1993 to 1994, he headed the Import / Export desk of Elf Hydrocarbons, and from 1994 to 1996, he was the personal assistant of the Managing Director of the Mitteldeutsche Erdöl Raffinerie Construction project in Leuna, Germany. In 1996, he was appointed Head of the Product Quality Department at Elf Antar France, and then headed that company’s Strategy team from 1999 to 2000. From 2000 to 2003, he worked as Senior Strategy Consultant for TotalFinaElf and became General Manager for HFO sales and then General Manager Bitumen of Total France from 2006 to 2009. In November 2009, he was appointed Vice President of Total ACS (Additives & Special fuels) in Lyon, and in 2012 he became General Manager of Commercial Sales at Total France. In July 2013, he became Vice President Lubricants and Chief Executive Officer of Total Lubrifiants, SA. Mr. Charleux holds a Master’s degree in Chemistry and Chemical Engineering from the École Supérieure de Chimie Physique Électronique de Lyon.

Mr. Charleux was appointed as a director pursuant to director designation rights granted to TMS in June 2018, in a transaction described under “Certain Relationships and Related Party Transactions” below. Mr. Charleux brings to our Board extensive natural gas and energy industry experience, significant management skills and key relationships within the TOTAL group.

James C. Miller III has served as a director of our Company since May 2006. Mr. Miller served on the board of governors of the United States Postal Service from April 2003 to December 2011 and as its Chairman from January 2005 to 2008. Mr. Miller served on the board of directors of the Washington Mutual Investors Fund from October 1992 to December 2017. From 1981 to 1985, Mr. Miller was Chairman of the U.S. Federal Trade Commission in the Reagan Administration, and also served as Director of the U.S. Office of Management and Budget from 1985 to 1988. In 2017, Mr. Miller began serving as a Senior Fellow of the Administrative Conference of the United States, an independent federal agency dedicated to improving the administrative process. Mr. Miller earned a B.B.A. from the University of Georgia and a Ph.D. from the University of Virginia.

Mr. Miller brings to the Board significant financial expertise and extensive knowledge of regulatory affairs gained during his service on the board of governors of the United States Postal Service, as Chairman of the U.S. Federal Trade Commission and as Director of the U.S. Office of Management and Budget. Mr. Miller also contributes financial acumen and experience dealing with large and financially complex organizations.

Thomas Maurisse has served as a director of our Company since February 2021, when he was appointed to the Board pursuant to TMS’ director designation rights described elsewhere in the Proxy Statement. Mr. Maurisse has served as Senior Vice President LNG for Total’s Gas, Renewables & Power Branch since 2019 where he oversees the renewable natural gas business, among others. Mr. Maurisse began his career in 2007 in the French Ministry of Economy, Finance & Industry where he became, in 2011, Chief of Staff of the State Secretary for Consumption, Small Enterprises, Trade & Services and Deputy Chief of Staff of the Minister of Economy, Finance & Industry. Mr. Maurisse joined Total in 2012 in the Refining & Chemicals Branch, where he worked successively in Germany as Head of the Economic Division of the Leuna refinery, then in Belgium as General Manager of the Supply Sales and Optimization activities for North and East Europe. In 2017, he joined the Exploration & Production Branch of Total as Strategy and Sales Director of Total EP Nigeria. Mr. Maurisse graduated from the Ecole Polytechnique in 2004 and the Ecole de Mines (Paris) in 2007.

Mr. Maurisse was appointed as a director pursuant to director designation rights granted to TMS in June 2018, in a transaction described under “Certain Relationships and Related Party Transactions” below. He brings to our Board significant renewable natural gas and energy industry experience, significant management skills and key relationships within the TOTAL group.

Kenneth M. Socha has served as a director of our Company since January 2003. From 1995 until his retirement at the end of 2014, Mr. Socha served as a Senior Managing Director of Perseus, L.L.C., a private equity fund management company. Previously, Mr. Socha practiced corporate and securities law as a partner in the New York office of Dewey Ballantine. Mr. Socha earned an A.B. from the University of Notre Dame and a J.D. from Duke University Law School.

Mr. Socha brings to our Board legal insight gained during his distinguished legal career and the perspective and financial acumen of a highly successful private equity investor.

Vincent C. Taormina has served as a director of our Company since April 2008. Mr. Taormina is the former Chief Executive Officer of Taormina Industries, Inc., one of California’s largest solid waste and recycling companies. In 1997, Taormina Industries merged with Republic Services, a publicly-held waste handling company that operates throughout the United States. Mr. Taormina served as Regional Vice President of Republic Services from 1997 to 2001, managing the overall operations of eleven western states. Since 2001, Mr. Taormina has served and continues to serve as a consultant to Republic Services and is a private investor. Mr. Taormina is a past President of the Orange County Solid Waste Management Association, past President Elect of the California Refuse Removal Council and a former board member of the Waste Recyclers Council for the National Solid Waste Management Board.

Mr. Taormina brings to our Board the perspective of a highly successful entrepreneur and industry leader in the refuse and recycling industry.

Parker A. Weil has served as a director of our Company since June 2020. Since August 2018, Mr. Weil has served as Vice Chairman of Investment Banking at Cowen and Company (Nasdaq:COWN) and has extensive financial and investment banking experience gained through over 30 years of providing M&A advice and capital raising services to companies in the energy & power, manufacturing, and business services industries. From June 2012 to April 2018, Mr. Weil was Managing Director of investment banking for Stifel Financial Corp. Prior to that, he spent 15 years at Bank of America Merrill Lynch, serving as Managing Director and Group Head – Energy & Power Group and thereafter Group Head – Middle Market Coverage and Execution Group. Since July 2017, he has served on the board of directors of 180 Degree Capital Corp. (Nasdaq:TURN), where he is Chairman of the Compensation Committee and a member of the Audit Committee and the Valuation Committee. Mr. Weil holds a Bachelor of Arts in Economics from the University of Pennsylvania and an MBA in Finance from the Kellogg Graduate School of Management at Northwestern University.

Mr. Weil brings to our Board significant financial and investment banking expertise and extensive knowledge in the energy and power industry. Mr. Weil also contributes business acumen and the perspective and financial acumen of a successful investment banker.

Selecting Our Director Nominees

Under its charter and our corporate governance guidelines, our nominating and corporate governance committee is responsible for reviewing with the Board, on an annual basis, the requisite skills and characteristics of potential new Board members, as well as the composition of the Board as a whole. This assessment includes an analysis of each member’s qualifications as a director and each member’s independence, as well as consideration of age, experience and other diversity factors in the context of the needs of the Board.

Minimum Criteria

Pursuant to our corporate governance guidelines, a majority of our directors must meet the standards for independence as required by Nasdaq, and no director may serve on more than historical factsthree other public company boards of directors unless approved in advance by the Board. Further, applicable Nasdaq rules provide that at least one member of our Board must meet the criteria for an “audit committee financial expert” as defined by SEC rules, and relatethe members of certain of our Board committees must satisfy enhanced independence and financial expertise standards under applicable Nasdaq and SEC rules. We also believe all directors should possess the following attributes:

·      Professional ethics and values, consistent with our code of ethics (described below under “Corporate Governance—Code of Ethics”);

·      A commitment to future eventsbuilding stockholder value;

·      Business acumen and broad experience and expertise at the policy-making level in one or circumstances or our future performance,more of the areas of particular consideration described under “Key Qualifications, Skills and they areAttributes” below;

·      The ability to provide insights and practical wisdom based on our current assumptions, expectationsthe individual’s experience or expertise; and beliefs concerning future developments

·      Sufficient time to effectively carry out duties as a Board member.

Other than the foregoing, there are no stated minimum criteria for director nominees, and theirthe nominating and corporate governance committee may consider these factors and any such other factors as it deems appropriate. The nominating and corporate governance committee does, however, review the activities and associations of each potential effectdirector candidate to ensure there is no legal impediment, conflict of interest or other consideration that might hinder or prevent service on our business.Board.

Diversity

Although we do not have a formal policy with respect to Board diversity, the nominating and corporate governance committee strives to assemble a board of directors that brings to our Company a variety of perspectives, skills and expertise. To achieve this, the nominating and corporate governance committee considers individuals from various disciplines and backgrounds in recommending director nominees to the Board, including diversity characteristics that may be self-identified by directors or director nominees, such as race, gender, military service, or other socioeconomic or demographic characteristics. The nominating committee also seeks to recommend directors who possess a broad range of business, professional, governmental, community involvement and natural gas and energy industry experience.

The nominating and corporate governance committee assesses these and other factors as it deems appropriate in connection with its annual review of each director and the Board as a whole and takes these factors into account when determining whether to nominate existing directors for re-election in connection with this annual review. The nominating and corporate governance committee also takes these factors into account when considering any director nominee outside of its annual review process, such as when a vacancy exists on the Board or when a stockholder suggests a new director candidate that the committee or the Board decides to consider for a mid-year appointment. In some cases, you can identify forward-looking statementsaddition, as part of its annual self-evaluation process, the nominating and corporate governance committee assesses its consideration of diversity in identifying and evaluating director candidates, including the key qualifications, skills and attributes that it aims for directors to possess.

The nominating and corporate governance committee is committed to further diversifying the Board across a number of metrics, including gender and representatives of underrepresented communities. In September 2018, California enacted a law requiring publicly held corporations whose principal executive offices are located in California to have at least one female director on their boards by the following words: “if,” “may,” “might,” “shall,” “will,” “can,” “could,” “would,” “should,” “expect,” “intend,” “plan,” “goal,” “objective,” “initiative,” “anticipate,” “believe,” “estimate,” “predict,” “project,” “forecast,” “potential,” “continue,” “ongoing” orend of the negative2019 calendar year and, if our Board maintains its existing size, at least three female directors by the end of the 2021 calendar year. On September 30, 2020, California enacted a law requiring California-headquartered public companies to have at least one director on its board from an underrepresented community, and if our Board maintains its existing size, at least three directors from underrepresented communities by the end of calendar year 2022. Because our principal executive offices are located in California, the nominating and corporate governance committee intends to comply with the requirements of these termslaws on or other comparable terminology, althoughbefore the absenceapplicable deadlines. Our Board appointed Lizabeth Ardisana, female Hispanic business owner, as a director in December 2019, and the nominating and corporate governance committee is actively reviewing and evaluating a number of these words does not mean thatpotential female director candidates and candidates from underrepresented communities for appointment or election at a statementfuture date.

Board Refreshment

Board members with a diversity of life experiences, backgrounds and gender are important to bring a variety of perspectives to our Board, as discussed under “Diversity.” We aim to regularly bring new directors to our Board at a responsible pace to ensure the Board benefits from fresh ideas and perspectives, while balancing the importance of directors who have experience with our Company.

Board refreshment is not forward-looking. a key matter considered during our annual Board and committee self-evaluations. In 2018 we added Momar Nguer and Philippe Montantême to the Board. Also, in 2018 T. Boone Pickens, our co-founder, retired from his position as an active director and became a director emeritus, an honorary position in recognition of his long-standing, loyal and dedicated services and singularly significant contributions to the Company; Mr. Pickens held such honorary position until passing away in September 2019. Lizabeth Ardisana joined the Board in 2019. In 2020 Mr. Nguer was replaced by Phillippe Charleux, long-time directors Warren Mitchell and James O’Connor retired from the Board, and Parker Weil was added to the Board. In 2021 Thomas Maurisse replaced Philippe Montantême; John Herrington, an original director, retired from the Board. We are grateful to all our former directors for their exemplary service. Other long-time directors may retire, and we expect to add one or more additional female directors before the end of 2021.

Key Qualifications, Skills and Attributes

The forward-looking statements we makenominating and corporate governance committee regularly reviews the appropriate skills and characteristics required of Board members in this Supplement include statements about, among other things, our ability to obtain stockholder approval for and implement anythe context of the matters discussedcomposition of the Board, our operating requirements, and the long- term interests of stockholders. When conducting its review of the key qualifications, skills and attributes desired of Board members, the nominating and corporate governance committee particularly considers:

From time to time, the nominating and corporate governance committee will also consider such other qualifications, skills and attributes as it deems appropriate given the needs of the Board and the Company to maintain a balance of knowledge, experience, background and capability.

Director Nominee Evaluations

At least annually, our nominating and corporate governance committee leads an evaluation of each of our directors and our Board as a whole and each of its committees. In evaluating whether a current director should continue to serve on our Board, the nominating and corporate governance committee considers a number of factors, including the minimum criteria and diversity goals described above and each director’s qualifications, skills and attributes in this Supplement or otherwisethe areas identified by the committee as particularly important to our Board. In concluding that each of the director nominees should continue to serve as directors of the Company, the nominating and corporate governance committee considered their knowledge, experience and expertise in these areas as indicated in the table below, which they gained from their professional backgrounds described under “Director Nominees” above.

OUR BOARD RECOMMENDS A VOTE “FOR ALL” THE DIRECTOR NOMINEES

NAMED IN THIS PROPOSAL 1

PROPOSAL 2

RATIFICATION OF APPOINTMENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

General

We are asking our stockholders to ratify the appointment of KPMG LLP as our independent registered public accounting firm for our fiscal year ending December 31, 2021. KPMG LLP has audited our financial statements annually since 2001. Representatives of KPMG LLP are expected to be voted onpresent at the Annual Meeting (includingto answer appropriate questions and make a statement if they desire to do so.

Although our amended and restated bylaws do not require that our stockholders approve the issuance and saleappointment of allour independent registered public accounting firm, we are submitting the appointment of KPMG LLP to our stockholders for ratification as a matter of good corporate practice. If our stockholders vote against the ratification of the 50,856,296 sharesappointment of KPMG LLP, the audit committee of the Board may consider whether to retain the firm. Even if our stockholders ratify the appointment of KPMG LLP, the audit committee of the Board may choose to appoint a different independent registered public accounting firm at any time during the year if the committee determines that such a change would, in its judgment, be in the best interests of our common stockCompany and our stockholders.

Independent Registered Public Accounting Firm Fees and Services

The following table shows the aggregate fees billed to Total underus for services rendered by KPMG LLP during the Purchase Agreement, which would require stockholder approvalperiods presented:

(1)    Audit fees consist of Proposals 4fees billed for professional services rendered for the audit of our annual consolidated financial statements and 5 describedreview of our interim condensed consolidated financial statements included in this Supplement andour quarterly reports, the satisfactionaudit of our internal control over financial reporting, audits of stand-alone financial statements of certain other conditions; the increase to the number of shares of our common stock we are authorized to issue, which would require stockholder approvalsubsidiaries, professional services rendered in connection with our filing of Proposal 5 described in this Supplement; the implementation of the Reverse Stock Split, which would require stockholder approval of Proposal 6 described in this Supplement;various registration statements (such as registration statements on Form S-8 and the finalization and establishment of certain other relationships with Total, which are not being voted on by our stockholders at the Annual Meeting but which are described in Proposal 4 of this Supplement), and if such stockholder approval is obtained and such matters are implemented, the possible effects such matters could have on us, our securities, our performance and our business.

Although the forward-looking statements in this Supplement reflect our good faith judgment based on available information, they involve known and unknown risks, uncertaintiesForm S-3, including related comfort letters) and other factorsservices that may cause actual achievements, performanceare normally provided by KPMG LLP in connection with statutory and regulatory filings or other eventsengagements.

Pre-Approval Policies and Procedures

Pursuant to be materially different from any future achievements, performance or other events expressed or implied by the forward-looking statements. Factors that might cause or contribute to such differences include, among others: our audit committee charter, all audit and Total’s ability to satisfy all of the conditions required to complete the issuancepermitted non-audit and sale of the shares of our common stock under the Purchase Agreement, some of which may not be within our control; our and Total’s ability to negotiate definitive agreements for certain other relationships discussed in this Supplement, both with each other and with certain other parties over which we have no control,tax services, as well as the finalfees and terms of these definitive agreements, if finalized; future supply, demand, use and prices of crude oil, gasoline, diesel, natural gas, other vehicle fuels, and heavy-duty trucks and other vehicles and engines poweredsuch services, that are provided by these fuels, including overall levels of and volatility in these factors;our independent registered public accounting firm are pre-approved by the willingness of fleets and other consumers to adopt natural gas as a vehicle fuel, and the rate of any such adoption; our ability to capture a substantial shareaudit committee of the marketBoard. The audit committee may also delegate authority to grant pre-approvals to one or more audit committee members, provided that the pre-approvals are reported to the full audit committee at its regularly scheduled meetings. In considering such services for alternative vehicle fuelsapproval, the audit committee considers, among other things, whether the provision of the services is compatible with maintaining the independence of our independent registered public accounting firm.

All services provided by KPMG LLP in 2019 and vehicle fuels generally2020 were pre-approved by the audit committee in accordance with the foregoing pre-approval policy.

OUR BOARD RECOMMENDS A VOTE “FOR” THE RATIFICATION OF THE APPOINTMENT OF

KPMG LLP AS OUR INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

PROPOSAL 3

ADVISORY, NON-BINDING VOTE TO APPROVE EXECUTIVE COMPENSATION

The Dodd-Frank Wall Street Reform and otherwise compete successfullyConsumer Protection Act of 2010 (“Dodd-Frank Act”) enables our stockholders to vote to approve, on an advisory, non-binding basis, the compensation of our named executive officers as disclosed in these markets, includingthis Proxy Statement in accordance with the eventSEC’s compensation disclosure rules.

As described in detail under “Compensation Discussion and Analysis” below, our executive compensation program is designed to attract, retain and motivate talented and dedicated executive officers; to reward individual performance and achievement of advanceskey corporate objectives without promoting excessive or improvements innon-natural gas vehicle fuels or engines powered by these fuels or other competitive developmentsunnecessary risk-taking; to align the interests of our executives with those of our stockholders; and particularlyto provide compensation that we believe is fair in light of increasing competition from new entrantsan executive’s experience, responsibilities, performance and tenure with our Company and in these markets, expanded programs by existing competitors, orrelation to the compensation provided to other factors;executives of our abilityCompany and certain peer companies. Under this program, determinations regarding each named executive officer’s compensation are based on, among other factors, the individual’s performance and contribution to accurately predict natural gas vehicle fuel demandour strategic plans and other business objectives; the Company’s overall performance, in light of business and industry conditions; general industry benchmarks and trends, including the compensation practices of certain peer companies; the level of the individual’s responsibility; the seniority of the individual; the individual’s long-term commitment to our Company; the available pool of individuals with similar skills; principles of pay equity and relative pay; the role of each compensation component in achieving the objectives of our executive compensation program; and the compensation committee’s business judgment and experience. Please read the “Compensation Discussion and Analysis” beginning on page 41 for additional details about our executive compensation program.

We are asking our stockholders to indicate their support for our named executive officer compensation as described in this Proxy Statement. We believe the compensation of our named executive officers is appropriate and serves to both incentivize and retain our highly skilled executive leadership team. Attracting, retaining and motivating key executives is crucial to our success. This say-on-pay proposal gives our stockholders the opportunity to indicate whether they approve of our named executive officers’ compensation. This vote is not intended to address any specific component of compensation, but rather relates to the overall compensation of our named executive officers and our executive compensation philosophy, policies and practices described in this Proxy Statement in accordance with the SEC’s compensation disclosure rules. Accordingly, we ask that our stockholders vote “FOR” the following resolution at the Annual Meeting:

“RESOLVED, that the Company’s stockholders approve, on an advisory, non-binding basis, the compensation of the Company’s named executive officers, as disclosed in the geographic and customer markets in which we operate and effectively calibrate our strategies, timing and levelsCompany’s Proxy Statement for its 2021 Annual Meeting of investmentsStockholders pursuant to be consistent with this demand; our ability to recognize the anticipated benefits of our natural gas fueling station network; future availability of capital, including equity or debt financing, as needed to fund the growth of our business, repayment of our debt obligations or other expenditures, as well as any dilutive or other negative effects or costs of obtaining such capital as and when needed; the availability of environmental, tax and other government regulations, programs and incentives that promote natural gas or other alternatives as a vehicle fuel, including long-standing support for gasoline- and diesel-powered vehicles and growing support for electric and hydrogen-powered vehicles that could result in programs or incentives that favor of these vehicles or vehicle fuels over natural gas; changes to federal, state or local greenhouse gas emissions regulations or other environmental regulations applicable to natural gas production, transportation or use; compliance with other applicable government regulations; our ability to manage and grow our renewable natural gas business, including

our ability to continue to receive revenue from sales of certain tradable credits we generate by selling conventional and renewable natural gas as vehicle fuel; construction, permitting and other factors that could cause delays or other problems at station construction projects; our ability to realize the intended or any benefits of any mergers, acquisitions, divestitures, investments or other strategic measures, transactions or relationships we may implement or pursue, as well as any negative effects or other costs associated with any such measures, transactions or relationships; general political, regulatory, economic, market and other conditions; the impactcompensation disclosure rules of the above factorsSecurities and other events,Exchange Commission, including the eventsCompensation Discussion and other matters discussed in this Supplement, onAnalysis, the market price, trading volume, liquidity and marketability of our common stock;Summary Compensation Table and the other risks discussed under “Risk Factors” in our annual report on Form10-K for our fiscal year ended December 31, 2017, which was filed with the SEC on March 13, 2018related tables and disclosure included therein.”

This say-on-pay proposal is included as part of the Annual Report. In addition, we operate in a competitive and rapidly evolving industry in which new risks emerge from time to time, and it is not possible for us to predict all of the risks we may face, nor can we assess the impact of all factors on our business or the extent to which any factor or combination of factors could cause actual results to differ from our expectations.

As a result of these and other potential risks and uncertainties, the forward-looking statements we make in this Supplement should not be relied on or viewed as predictions of future events. All forward-looking statements in this Supplement are made only as of the date of this document and, exceptbeing provided as required by law,Section 14A of the Exchange Act and is advisory and therefore not binding on the Company, the compensation committee or our Board in any way. Our Board and our compensation committee value the opinions of our stockholders, and to the extent there is any significant vote against the named executive officer compensation as disclosed in this Proxy Statement, we undertake no obligationwill consider our stockholders’ concerns and the compensation committee will evaluate whether any actions are necessary to update publicly any forward-looking statements for any reason, includingaddress these concerns.

Our current policy is to conform these statementsprovide stockholders with an opportunity to actual results or to changes invote on the compensation of our expectations.named executive officers each year at the annual meeting of stockholders. It is expected that the next such advisory vote will occur at the 2022 annual meeting of stockholders.

OUR BOARD RECOMMENDS A VOTE “FOR” THE APPROVAL OF THE COMPENSATION OF

OUR NAMED EXECUTIVE OFFICERS, AS DISCLOSED IN THIS PROXY STATEMENT

PURSUANT TO THE COMPENSATION DISCLOSURE RULES OF THE SEC

PROPOSAL 4

APPROVAL, FOR THE PURPOSE OF COMPLYING WITH NASDAQ LISTING RULES 5635(B) AND 5635(D)RULE 5635(b), OF THE ISSUANCE OF SHARES
OF OUR COMMON STOCK TO TOTAL IN A PRIVATE PLACEMENT PURSUANT TO THE TERMSUPON EXERCISE OF THE PURCHASE AGREEMENTAMAZON WARRANT

Background

Our Board is proposing for approval by our stockholders, for

On April 16, 2021, in connection with execution of the purposeFuel Agreement with a subsidiary of complyingAmazon, we entered into the Transaction Agreement with applicable Nasdaq rules, our issuanceAmazon under which, among other things, we issued the Amazon Warrant to another subsidiary of 50,856,296Amazon to purchase up to an aggregate of 53,141,755 shares of our common stock, subject to Total underadjustment and vesting in accordance with the Purchase Agreement. The key terms and conditions set forth in the Amazon Warrant.

Our Board recommends that our stockholders approve our issuance of shares of our common stock in excess of 50,595,531 shares (the “Share Cap”) pursuant to, and upon exercise of, the agreements relatingAmazon Warrant, in order to this Proposal 4 are summarized below. Copiesensure such issuance complies with Nasdaq Listing Rule 5635(b). The Share Cap represents the highest number of shares of our common stock that can be issued pursuant to the Amazon Warrant without potentially requiring the approval of our stockholders under Nasdaq Listing Rule 5635(b). We filed a copy of the agreements have been filedAmazon Warrant as Exhibits 10.125, 10.126 and 10.127Exhibit 4.4 to our QuarterlyCurrent Report onForm 10-Q for the fiscal quarter ended March 31, 2018 filed8-K with the SEC on May 10, 2018, and youApril 19, 2021. You are encouraged to reviewread the full text of such agreementsthe Amazon Warrant and such report. The below summary of these agreementsthe Amazon Warrant and therelated transactions contemplated thereby does not purport to be complete and is subject to and is qualified in its entirety by, the full text of the agreements.Amazon Warrant.

The Purchase AgreementAmazon Warrant and Related Agreements

On May 9, 2018, we entered into

The Warrant Shares vest in multiple tranches, the Purchase Agreement with Total, pursuant tofirst of which we agreed to sellfor 13,283,445 Warrant Shares vested upon execution of the Fuel Agreement. Subsequent tranches can vest over time based on discretionary fuel purchases or other spending by Amazon and issue, and Total agreed to purchase, in a private placement,its affiliates, up to 50,856,296 sharesa total of our common stock$500 million. Subject to vesting and certain other conditions, the Amazon Warrant may be exercised, in whole or in part, at a purchaseany time before April 16, 2031 at an exercise price of $1.64$13.49 per share, which was determined based on the 30-day volume-weighted average price for our common stock between March 23, 2018 (the day on which discussions began between us and Total) and May 3, 2018 (the day on which we agreed in principal with Total regarding the structure and basic terms of its investment). If all of the shares to be sold under the Purchase Agreement are issued, then we would receive gross proceeds from such sale of $83.4 million and, immediately after such issuance (and based on the number of shares of our common stock outstanding as of April 10, 2018, which was 152,514,550 shares), Total would hold 25.0% of15, 2021, and is 21.3% more than the outstanding shares$11.12 closing price of our common stock andon April 15, 2021, the largest ownership position ofday prior to our Company. Asissuance of the date of the Purchase Agreement, Total did not hold or otherwise beneficially own any shares of our common stock, and Total has agreed, until the later of May 9, 2020 or such date when it ceases to hold more than 5% of our common stock then outstanding, among other similar undertakings and subject to customary conditions and exceptions, to not purchase shares of our common stock or otherwise pursue transactions that would result in Total beneficially owning more than 30% of our equity securities without the approval of the Board.Amazon Warrant.

The issuance, saleAmazon Warrant may be exercised for cash or on a cashless basis. If Amazon were to vest and purchase ofcash exercise part or all of the shares under the Purchase Agreement is conditioned upon the satisfaction or waiver (if and to the extent permitted by applicable laws, rules and regulations) of certain specified conditions. These conditions include the following:

As a result, with this Proposal 4, we are seeking the approval of our stockholders to issue to Total all of the 50,856,296 shares of our common stock to be sold under the Purchase Agreement. If, however, our stockholders do not approve this Proposal 4 or Proposal 5 described in this Supplement below,

then, pursuant to the Purchase Agreement, Total would have the right, exercisable in its sole discretion within two calendar weeks after the conclusion of the Annual Meeting, to elect to purchase fewer shares of our common stock, in an amount equal to 19.99% of the lesser of the number of shares of our common stock outstanding immediately before the Purchase Agreement was signed (which was 152,568,887 shares, and 19.99% of which is 30,498,520 shares), and the number of shares of our common stock outstanding immediately before Total’s delivery to us of a notice indicating its election to exercise such right. Any such purchase of fewer shares of our common stock would be completed under the terms of the Purchase Agreement, including the price per share set forth in such agreement and as described above. As a result, if our stockholders do not approve this Proposal 4, we would, if elected by Total, issue and sell to Total either no shares of our common stock under the Purchase Agreement, and receive no gross proceeds therefor, or 30,498,520 shares of our common stock under the Purchase Agreement, and receive $50.0 million of gross proceeds therefor.

We expect to use any net proceeds received from TotalAmazon under the Purchase AgreementAmazon Warrant for working capital and general corporate purposes, which may include, among other purposes, executing our business plans, and pursuing opportunities for further growth, and retiring a portion of our outstanding indebtedness.growth. As of the date of this solicitation, however, we cannot specify with certainty all of the particular uses of such proceeds, if any, and we will have broad discretion over the use of any such proceeds. Pending our use of the net proceeds, if any, we may invest the proceeds in short-term, interest-bearing, investment-grade securities.

If stockholder approval of this Proposal 4 is obtained at

Anti-Dilution Adjustments and Other Rights

Both the Annual Meetingexercise price and the other conditions described abovenumber of Warrant Shares subject to purchase under the Amazon Warrant are also satisfied, then we expectsubject to sell and issue all suchcustomary anti-dilution adjustments, including as a result of any dividend or distribution of additional shares promptly after the satisfaction of all conditions.

Director Designation Rights

Pursuant to the Purchase Agreement, we have granted to Total the right to designate up to two individuals to serve as directors on our Board.common stock or stock split, subdivision, combination or reclassification involving our common stock. Subject to certain limited conditions as describedexceptions, the exercise price and number of Warrant Shares issuable upon exercise of the Amazon Warrant are also subject to adjustment in connection with certain repurchases by us of our outstanding common stock. Further, in the Purchase Agreement, including compliance with our governing documents and all applicable laws, rules and regulations,event we issue, or commit to issue, any equity securities in a financing to raise capital within six months after the issuance of the Amazon Warrant, the number of Warrant Shares subject to the Amazon Warrant will be obligatedincreased to appoint or nominate for election as directorsa number that would represent 19.999% of our Companyoutstanding common stock on a fully diluted basis after giving effect to such financing (the “Financing Adjustment”).

In the individuals so designated by Total and, from and after such appointmentevent we make certain other specified dividends or election, appoint onedistributions on shares of these individualsour common stock, Amazon Holdings will be deemed to serve onhave exercised the audit committeevested portion of the BoardWarrant Shares and any other committees of the Board that may be formed from time to time for the purpose of making decisions that are strategically significant to our Company. Total’s rights and our obligations relating to these designees commence at the time any shares are issued to Total under the Purchase Agreement, and continue until (and if) (1) with respect to Total’s right to designate two individuals to serve as directors on our Board, Total’s voting power is less than 16.7% but more than 10%, and (2) with respect to Total’s right to designate one individual to serve as a director on our Board, Total’s voting power is less than 10%, in each case measured in relation to the total votes then entitled to be castparticipate in an electionsuch dividend or distribution. In addition, in the event of directors by our stockholders.

This Proposal 4 does not relate to, and is not a vote on, the election of these director nominees. We expect the individuals selected by Total to serve as directors on our Board will be identified, considered and reviewed by our Board to confirm compliance with all applicable laws, rules and regulations andcertain acquisition transactions involving us under conditions as set forth in the PurchaseAmazon Warrant, all unvested Warrant Shares will automatically vest and become exercisable.

Stockholder Approval Requirement

Under the terms of the Transaction Agreement, we are required to use our commercially reasonable efforts to obtain the approval of our stockholders with respect to the issuance of shares of our common stock in excess of the Share Cap (the “Stockholder Approval”), as may be required pursuant to Nasdaq Listing Rule 5635(b). Until the Stockholder Approval is obtained, Nasdaq Listing Rule 5635(b) may restrict the issuance of shares of our common stock exceeding the Share Cap pursuant to, and appointedin the event of an exercise of, the Amazon Warrant. In connection with obtaining the Stockholder Approval and under the Transaction Agreement, we agreed to file a proxy statement and hold a meeting of our stockholders as promptly as practicable to obtain the Stockholder Approval. If the Stockholder Approval is not obtained at a meeting of our stockholders called for such purpose, we are required, at Amazon’s request, to cause an additional meeting of stockholders to be held every twelve (12) months thereafter until either the Stockholder Approval is obtained or the term of the Amazon Warrant expires.

Support Agreements

In connection with the requirement for Stockholder Approval and pursuant to the terms of the Transaction Agreement, we have entered into Support Agreements by and among us, Amazon and each of our executive officers, members of our board of directors onwho are independent directors within the meaning of applicable rules of Nasdaq and the T. Boone Pickens Trust, under which each such stockholder has irrevocably agreed, among other things, to vote the number of shares of our Boardcommon stock beneficially owned by such stockholder and for one such individual, as a memberwhich he, she or it has or shares voting power in favor of the audit committee thereof, on aStockholder Approval. Each stockholder’s agreements pursuant to the Support Agreement will continue until either the Stockholder Approval is obtained or the term of the Amazon Warrant expires. As of April 19, 2021, the record date followingfor the Annual Meeting. As a result, we expect these individuals will be nominated and eligible for electionMeeting, an aggregate of 11,169,592 shares of our common stock, representing 5.6% of the outstanding shares of our common stock as of such date, were owned or controlled by our stockholders atindependent directors, executive officers and the T. Boone Pickens Trust and are subject to the Support Agreements.

Beneficial Ownership Limitation

Under the terms of the Amazon Warrant, Amazon.com NV Investment Holdings LLC (“Amazon Holdings”) as the holder of the Amazon Warrant 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 our 2019 annual meetingcommon stock immediately outstanding after giving effect to such exercise (excluding any unvested portion of stockholders.the Amazon Warrant) (the “Beneficial Ownership Limitation”). Amazon Holdings may, however, waive or modify the Beneficial Ownership Limitation by providing us written notice sixty-one (61) days before such waiver or modification becomes effective (or immediately upon written notice to us to the extent we are subject to certain acquisition transactions pursuant to a tender or exchange offer).

Registration Rights

Pursuant

Under the Transaction Agreement, we also granted Amazon customary registration rights with respect to the Purchase Agreement, we have also agreedAmazon Warrant and the Warrant Shares, including (i) the right to enter into ademand registration of the sale of the Amazon Warrant and the Warrant Shares under the Securities Act, (ii) piggyback registration rights agreement with Total atto include the closingWarrant Shares as part of the issuance and sale of our common stock to Total under the Purchase Agreement. Pursuant to theany registration rights agreement, we will be obligated to, at our expense, (1) within 60 days after the issuance and sale of shares of our common stock to Total under the Purchase Agreement, file one or more registration statements with the SEC to cover the resale of such shares, (2) use our commercially reasonable

efforts to cause all such registration statements to be declared effective within 90 days after the initial filing thereof with the SEC, (3) use our commercially reasonable efforts to maintain the effectiveness of such registration statements until all such shares are sold or may be sold without restriction under Rule 144 under the Securities Act (except for a registration on Forms S-4 or S-8 and (4) withcertain other limitations set forth in the Transaction Agreement), and (iii) the right to require us to register the Amazon Warrant and the Warrant Shares on a viewForm S-3 shelf registration statement to making availableallow for the offering of the Amazon Warrant and the Warrant Shares for sale on a continuous basis pursuant to Rule 415 under the Securities Act. Our requirement to register the sale of the Amazon Warrant and the Warrant Shares as provided under clauses (i) through (iii) is, in each case, subject to the holdersterms and conditions set forth in the Transaction Agreement, including our payment of specified fees and expenses related to such sharesregistration. The registration rights under the benefitsTransaction Agreement will continue until the date on which the Amazon Warrant and all Warrant Shares have been disposed of Rule 144, makeby Amazon Holdings or any subsidiary of Amazon holding such securities.

Transfer and keep available adequate current public information,Standstill Restrictions

The Transaction Agreement also limits Amazon’s ability to transfer the Amazon Warrant to certain unaffiliated third parties and imposes customary standstill limitations on Amazon if, and so long as, defined in Rule 144,Amazon and timely fileits subsidiaries beneficially own at least 5% of our outstanding common stock.

Governance Rights

The Transaction Agreement does not provide Amazon with the SEC all required reports and other documents, until all such shares are sold or may be sold without restriction under Rule 144. If such registration statements are not filed or declared effective as described above orright to designate any such effective registration statements subsequently become unavailable for more than 30 days in any12-month period while they are required to be maintained as effective, then we would be required to pay liquidated damages to Total equal to 0.75% of the aggregate purchase price for the shares remaining eligible for such registration rights each month for each such failure (up to a maximum of 4% of the aggregate purchase price for the shares remaining eligible for such registration rights each year).

Voting Agreement

In connection with the Purchase Agreement, on May 9, 2018, we and all of our directors and officers entered into a voting agreement with Total. Pursuant to the voting agreement, each of our current directors and officers has agreed to vote all shares of our common stock presently or hereafter owned or controlled by him, in any vote of our stockholders that may be held from time to time, in favor of certain matters, including the approval of this Proposal 4 at the Annual Meeting, the approval of Proposal 5 at the Annual Meeting (as described in this Supplement below), and the election of the individuals designated by Total to serve as directors on our Board. Each of our directorsBoard or, except as described herein, any rights and officers has also granted to Total a proxy to vote all such shares in accordanceprivileges beyond the rights and privileges associated with the terms of the voting agreement. For each of our directors and officers party to the voting agreement, the voting obligations contained in the agreement continue from and after, and for so long as, Total’s director designation rights are in effect, as described above, and such director or officer continues to serve in such capacity for our Company (other than Mr. Boone Pickens, one of our directors andco-founders, who will continue to be bound by the voting obligations even after he ceases to serve as such for our Company) and continues to hold shares of our common stock. As of April 10, 2018, an aggregate of 16,587,658 shares of our common stock representing 10.9% of the outstanding shares of our common stock as of such date, were owned or controlledheld by our directors and officers and are subject to this voting agreement.existing stockholders.

Separate Credit Support Arrangement with Total for Truck Leasing Program

As part of our key business objectives, we aim to facilitate and grow the deployment of heavy-duty natural gas trucks in the United States, which is one of our target customer markets, and to fuel a substantial number of these trucks. In connection with the Purchase Agreement, we have signed anon-binding letter of intent with Total regarding a truck leasing program and a credit support arrangement in connection with these objectives.

As described in our Annual Report, natural gas vehicles typically cost more initially than gasoline- or diesel-powered vehicles, because the components needed for a vehicle to use natural gas add to the vehicle’s base cost. Operators then seek to recover the additional base cost over time through the generally lower fueling costs for natural gas vehicles, but if operators perceive an inability to timely recover these additional initial costs, then they may be reluctant to initially purchase the natural gas vehicle. We and Total intend to work together to develop and implement a truck leasing program designed to encourage additional operators to convert to or acquire new natural gas heavy-duty trucks. In concept, and as described in the letter of intent, such a truck leasing program is expected to involve the following: (i) one or more truck leasing or finance companies would lease natural gas heavy-duty trucks to large vehicle fleets pursuant to lease agreements with the fleet operators and with us, providing for periodic payments by the fleet operators of amounts equal to the payments that would be made for the lease of an equivalent truck that operates on diesel fuel, and providing for periodic payments by us of the incremental cost of the natural gas truck over and above the diesel equivalent truck, (ii) the fleet operators would enter into fuel purchase agreements with us, pursuant to which the operators would agree to purchase minimum monthly volumes of natural gas fuel from us at fixed prices, and (iii) Total would commit to

enter into guaranty agreements for up to an aggregate of $100.0 million in support of our payment obligations under the truck lease agreements as described above, and in consideration for such guaranty commitment, we would pay to Total an annual fee equal to 10% of the average amount of all such outstanding guaranty agreements.

The letter of intent for the truck leasing program and related credit support arrangement isnon-binding in all respects, and therefore does not represent any legally binding obligation on the part of us or Total with respect to such program or arrangement or continued discussions or negotiations, if any, of definitive agreements for the program or arrangement. Furthermore, if we and Total agree to a truck leasing program and credit support arrangement, the terms of such program and arrangement could differ materially from those contemplated by the letter of intent as described above. Although we expect to work with Total to complete such definitive agreements as promptly as practicable, there is no assurance that any such agreements will be finalized when expected, on terms similar to those described above or terms we otherwise believe are favorable, or at all. Moreover, even if such definitive agreements are finalized and a truck leasing program and credit support arrangement are implemented, such a program and arrangement may not achieve the intended or any other benefits for us or our business.

Further, entering into definitive agreements for a truck leasing program and related credit support arrangement is not a condition to issuing and selling the shares of our common stock to Total under the Purchase Agreement as described in this Proposal 4, and we do not expect the issuance and sale of such shares of our common stock to Total under the Purchase Agreement would be a condition to entering into definitive agreements for the truck leasing program and credit support arrangement. As a result, the truck leasing program and credit support arrangement are separate from the issuance and sale of shares to Total under the Purchase Agreement in all respects (except solely for the commonality of parties to the proposed transactions), and this Proposal 4 does not relate to, and is not a vote on, such a program or arrangement. Consequently, if this Proposal 4 is approved by our stockholders (and the other conditions described above are satisfied), we may effect the issuance and sale of shares of our common stock to Total under the Purchase Agreement and receive the gross proceeds therefor without ever agreeing to the terms of and finalizing definitive agreements for or implementing a truck leasing program and credit support arrangement, and conversely, if this Proposal 4 is not approved by our stockholders (or any of the other conditions described above are not satisfied), we may finalize definitive agreements for and implement a truck leasing program and related credit support arrangement without ever effecting the issuance and sale of shares of our common stock to Total under the Purchase Agreement or receiving any gross proceeds therefor.

Reasons for Requesting Stockholder Approval

Our common stock is listed on the Nasdaq, Global Select Market, and as a result, we are subject to Nasdaq’s Listing Rules, including Nasdaq Listing Rule 5635.5635(b). Nasdaq Listing Rule 5635(b) requires stockholder approval prior to an issuance of securities that will result in a “change of control” of a listed company, which for Nasdaq purposes is generally deemed to occur when, as a result of an issuance, an investor or a group of investors acquires, or has the right to acquire, 20% or more of the outstanding shares of common stock or voting power of the company and such ownership or voting power would be the company’s largest ownership position. If Total purchasesthe Amazon Warrant vests in full and Amazon Holdings exercises the Amazon Warrant to purchase all of the 50,856,296 shares of our common stock that could be issued and sold under53,141,755 Warrant Shares initially subject to the Purchase Agreement, TotalAmazon Warrant, Amazon Holdings would become a holder of more than 20%approximately 21.0% of the outstanding shares of our common stock (immediately after the issuance of such shares and would holdbased on the largest ownership positionnumber of shares of our Company.common stock outstanding as of April 19, 2021). In such event, TMS, a subsidiary of TOTAL and our next largest stockholder, would own approximately 20.1% of our outstanding shares of common stock (excluding 7,898,021 shares of our common stock that are the subject of a voting agreement, dated May 9, 2018, among TMS, the Company and all of the Company’s then-directors and officers (the “TMS Voting Agreement”)); however, TMS would also continue to have the right to designate two individuals to serve as directors on our Board. See “Certain Relationships and Related Party Transactions—Related Party Transactions—Relationships with Total and its Affiliates” for further information. In the event we issue additional equity securities in a financing transaction on or prior to October 16, 2021, the number of Warrant Shares subject to the Amazon Warrant will be subject to a Financing Adjustment, which would have the effect of increasing Amazon’s potential ownership of our outstanding shares of common stock. As a result, our issuance of common stock pursuant to the Amazon Warrant, if exercised in full, could cause Amazon Holdings to own 20% or more of our common stock and sale to Total of all such shares would, for Nasdaq purposes, constitutebecome our largest stockholder, resulting in a “change of control” requiringfor purposes of Nasdaq Listing Rule 5635(b).

Accordingly, we are seeking stockholder approval pursuant to Nasdaq Listing Rule 5635(b).

In addition, Nasdaq Listing Rule 5635(d) requires stockholder approval prior to permit the sale, issuance or potential issuanceof Warrant Shares in a transaction other than a public offering of a listed company’s common stock (or securities convertible into or exercisable for common stock) equal to 20% or moreexcess of the common stock or 20% or more of the voting power outstanding before the issuance for less than the greater of book or market value of the common

stock, where, for Nasdaq purposes, “market value” equals the consolidated closing bid price per share of the common stock as reported by Nasdaq immediately before entry into a binding agreement to issue the securities. If all of the 50,856,296 shares of our common stock are issued and sold to Total under the Purchase Agreement, the totalShare Cap (which is highest number of shares of our common stock sold under such agreement would exceed 20% ofcan be issued pursuant to the total number of sharesAmazon Warrant without potentially requiring the approval of our common stock issued and outstanding immediately before the Purchase Agreement was signed, and all of our common stock to be sold and issued under such agreement would be sold at a price of $1.64 per share, which is less than $1.91, the consolidated closing bid price per share of our common stock as reported on the Nasdaq Global Select Market immediately before the Purchase Agreement was signed. As a result, our issuance and sale of all such shares of our common stock requires stockholder approvalstockholders pursuant to Nasdaq Listing Rule 5635(d)5635(b)).

Reasons for the Transactions with TotalAmazon

The

Our Board has determined, in its business judgment, that the transactions with TotalAmazon as described above, including the issuance and sale of shares of our common stock under the Purchase AgreementAmazon Warrant, and the potential truck leasing program and related credit support arrangement,possible future purchase by Amazon Holdings of the Warrant Shares issuable thereunder, are in the best interests of the Company and our stockholders. As a result, theOur Board has unanimously approved these transactions, subject to any required stockholder approval, as required, and has unanimously recommendedrecommends that our stockholders approve such transactions that require stockholder approval by votingvote in favor of this Proposal 4. In making this determination and approval, the Board considered, among other things, the factors and characteristics of the transactions described below.

First and most critically, the Board believes TotalAmazon is a valuable strategic investor and partner for our Company. TotalClean Energy. .Under the Fuel Agreement, Amazon will be purchasing low and negative carbon RNG from Clean Energy, initially through 27 existing fueling stations and 19 non-exclusive new or upgraded stations that we expect to construct by the end of the year. The new and existing stations will provide RNG in 15 different states across the United States, and we will own all the stations.

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, areup to a major global naturaltotal of $500 million, excluding any payments attributable to “Pass Through Costs,” which consist all costs associated with the delivered cost of gas and energy organization. In particular, Total is actively pursuing clean energy initiatives and has enthusiastically embraced naturalapplicable taxes determined by reference to the selling price, gallons or gas as a vehicle fuel. sold. Importantly, if all the vesting conditions of the Amazon Warrant are satisfied, Amazon will have purchased hundreds of millions of GGEs of RNG at today’s fuel prices from Clean Energy.

We believe a commercial partnership with Total couldAmazon will enhance our strategies, initiatives and efforts to achieve our goals to grow fleet and other consumer support for the use of natural gasRNG as a vehicle fuel infor our target customercustomers and geographic markets, through Total’s input of crucial insight and experience, its considerable influence in the global energy markets,geographies, and other contributions and factors. The Board also believes the proceeds from the saleissuance of our common stock to Total underAmazon in the Purchase Agreementevent Amazon were to vest and then exercise the Amazon Warrant in part or whole for cash, would enhance our liquidity in support of our operations, as well as our ability to execute our business plans and pursue opportunities for further growth, and our satisfaction of our commitments (including repayments on our outstanding debt). Further, the Board believes the potential truck leasing program and credit support arrangement with Total could play a critical role in generating increased adoption of natural gas as a vehicle fuel in the U.S. heavy-duty truck market, which, if this expectation materializes, could have a direct and positive impact on our financial condition and performance, and the Board believes Total’s purchase of our common stock under the Purchase Agreement would align Total’s interests with the interests of our other stockholders and the success of our Company, both in general and in connection with any truck leasing program and credit support arrangement that may be finalized.growth.

Possible Effects if Proposal 4 Is Approved

If this Proposal 4 is approved by our stockholders, then, subject to the satisfaction of the vesting and other conditions set forth in the Purchase AgreementAmazon Warrant, including as described below (including obtaining the approval of our stockholders of Proposal 5 as described in this Supplement below),herein, we would be able to issue to Amazon 2,546,224 shares (the “Additional Warrant Shares”) more than if our stockholders do not approve this proposal, subject to any future anti-dilution and sell 50,856,296other adjustments. If Amazon were to vest and exercise for cash the entire 53,141,755 shares under the Amazon Warrant, the 2,546,224 of Additional Warrant Shares subject to stockholder approval would represent approximately 1% of our outstanding common stock to Total underas of the Purchase Agreement. date of this proxy statement.

The rights and privileges associated with all shares of our common stock issuable to Total under the Purchase AgreementAmazon Warrant are identical to the rights and privilegesthose associated with theour existing common stock, held by our existing stockholders, and will not include preemptive, conversion or other rights to subscribe for additional shares of our common stock.

Approval of this Proposal 4, assuming the satisfaction of the vesting and other conditions set forth in the PurchaseWarrant Agreement and our issuance of the shares issuable thereunder, could have the following effects:

Possible Effects if Proposal 4 Is Not Approved

If this Proposal 4 is not approved by our stockholders, then, we would not be ablepursuant to issue and sell, and Total would not be able to purchase, allthe Amazon Warrant, the issuance of the 50,856,296 shares of our common stock issuable underexceeding the Purchase Agreement, nor would we receiveShare Cap upon exercise of the $83.4 million of gross proceeds fromAmazon Warrant may be restricted by the Nasdaq Listing Rule 5635(b). In such sale. As described above,event, however, in that event, or if Proposal 5 as described in this Supplement below is not approved by our stockholders, then TotalAmazon would have the right to purchase fewer sharesrequire us to cause an additional meeting of stockholders to be held every twelve (12) months thereafter until either the Stockholder Approval is obtained or the term of the Amazon Warrant expires. Accordingly, if our stockholders do not approve this Proposal 4, we anticipate that we would seek the Stockholder Approval again at or before our next annual meeting of stockholders and at one or more future meetings of our common stock if it electsstockholders thereafter until the Stockholder Approval is obtained or the term of the Amazon Warrant expires.

If we fail to do so, whichobtain the Stockholder Approval, we would result in our issuanceadversely impact the opportunity to obtain the maximum interest of Amazon. Our Board believes the potential value and sale to Total of either no sharesbenefits of our common stock underrelationship with Amazon then could be materially weakened. As discussed above, we believe our potential transactions with Amazon could prove to be important in the Purchase

Agreementtrajectory of Clean Energy, and our receipt of no gross proceeds therefor (if Total does not elect to exercise such right), or 30,498,520 shares of our common stock under the Purchase Agreement and our receipt of $50.0 million of gross proceeds therefor (if Total does elect to exercise such right). If Proposal 4 or Proposal 5 are not approved by our stockholders, then Total may elect to exercise or not exercise this right in its sole discretion, and consequently, we would have no control over whether or not such lesser number of shares would be issued and sold to Total.

Aa failure to obtain the approvalStockholder Approval could deprive us of our stockholderssome or all of this Proposal 4 could have the following effects:benefits we anticipate from these potential transactions and relationships.

Securities Law Matters

This Proposal 4, together with the other disclosures contained in this Supplement,Proxy Statement, is neither an offer to sell nor a solicitation of an offer to buy any of our securities.

The offerAmazon Warrant and sale of the shares issuable to Total under the Purchase AgreementWarrant Shares have not been registered under the Securities Act or under any state or foreign securities laws,law and may not be offered or sold absent such registration or an exemption from such registration requirements. These shares are beingwere offered and soldissued, as applicable, in reliance on anupon the exemption from registration afforded byrequirements of the Securities Act set forth in Section 4(a)(2) of the Securities Act, Regulation S underAct. Clean Energy did not engage in a general solicitation or advertising regarding the issuance of the Amazon Warrant. Amazon has represented to Clean Energy its intention to acquire the Amazon Warrant and Warrant Shares for investment purposes only and not with a view toward their resale, distribution or other disposition in violation of the Securities Act and Rule 506 of Regulation D under the Securities Act, primarily based on the following facts: (1) Total has represented to us that it is an accredited investor within the meaning of Rule 501 of Regulation D or a qualified institutional buyer within the meaning of Rule 144A, in each case under the Securities Act, and that it is not a U.S. person within the meaning of Rule 902 of Regulation S under the Securities Act; (2) Total has represented to us that it is acquiring the shares for its own account for investment only and with no present intention of distributing any of them or any arrangement or understanding with any other person regarding the distribution thereof, except in compliance with certain transfer restrictions set forth in the Purchase Agreement;

(3) Total has represented to us that it is knowledgeable, sophisticatedapplicable state securities laws, and experienced in making, and is qualified to make, decisions with respect to investments in securities presenting an investment decision like that involved in the purchase of the shares; (4) we used no advertising or general solicitation in connection with the offer and sale of the shares to Total; and (5) the shares that are issued to Totalappropriate legends will be issued as restricted securities.affixed to the Amazon Warrant and the Warrant Shares.

No Appraisal Rights

Under applicable Delaware law, our stockholders are not entitled to appraisal rights with respect to the proposed issuance and sale of our common stock to Total underAmazon Holdings upon exercise of the Purchase Agreement.Amazon Warrant.

Required Vote and Effect of Not Casting Your Vote

Proposal 4 must be approved by the affirmative vote of a majority of the votes cast on the proposal by shares of our common stock present or represented by proxy at the Annual Meeting and entitled to vote on the proposal at the Annual Meeting. We expect that Proposal 4 constituteswill constitute a“non-routine” “non-routine” matter on which a broker, bank or other nominee is not entitled to vote shares held on behalf of a beneficial owner without receiving specific voting instructions from the beneficial owner. Consequently, if you hold your shares in street name (such as through a brokerage account) and you do not instruct your broker, bank or other nominee on how to vote on this Proposal 4, no votea “broker non-vote” will be cast on the proposal on behalf of your shares and a “brokernon-vote” will occur. As a result of the above, abstentions,occur with respect to Proposal 4. Abstentions, if any, and broker non-votes with respect to Proposal 4 are not treated as votes cast and will have no effect onnot be counted in determining the outcome of the vote on Proposal 4 because abstentions are not considered to be present or entitled to vote with respect to the proposal for which they occur, and brokernon-votes, if any, will have no effect on the outcome of the vote on Proposal 4 because, pursuant to our amended and restated bylaws, brokernon-votes are not considered to be present or entitled to vote with respect to the proposal for which they occur.4.

OUR BOARD UNANIMOUSLY RECOMMENDS A VOTE “FOR” THE APPROVAL OF

THE ISSUANCE OF THE WARRANT SHARES UPON EXERCISE OF OUR COMMON STOCK TO TOTALTHE AMAZON WARRANT

IN A PRIVATE PLACEMENT PURSUANT TO THE PURCHASE AGREEMENT

PROPOSAL 5

APPROVAL OF AMENDMENT TO OUR RESTATED CERTIFICATE OF INCORPORATION

TO INCREASE THE AUTHORIZED SHARES OF OUR COMMON STOCK

Our Restated Certificate currently authorizes the issuance of 224,000,000304,000,000 shares of our common stock, par value $0.0001 per share. Our Board is proposing for approval by our stockholders an amendment to our Restated Certificate to increase the number of shares of our common stock we are authorized to issue by approximately 35.7%49%, from 224,000,000304,000,000 shares to 304,000,000454,000,000 shares. Our Restated Certificate also authorizes the issuance of 1,000,000 shares of preferred stock, par value $0.0001 per share, which would remain unchanged by the amendment to our Restated Certificate contemplated by this Proposal 5.

Background: Current Capitalization

As of April 10, 2018,16, 2021, our capitalization was as follows:

Based on the above capitalization information, only 40,818,03522,772,544 shares of our currently authorized common stock remained unissued and unreserved and available for future issuance as of April 10, 2018. As described in Proposal 4 above, we have agreed to sell and issue to Total, and Total has agreed to purchase, 50,856,296 shares of our common stock if our stockholders approve Proposal 4 and this Proposal 5 and certain other conditions are satisfied (although we may be obligated to issue and sell a lesser number of shares to Total under the Purchase Agreement even if Proposal 4 or this Proposal 5 are not approved, please see the description of Proposal 4 above for more information). As a result, there is an insufficient number of unissued and unreserved shares of our common stock currently authorized to permit the issuance of all such shares to Total under the Purchase Agreement.16, 2021.

Reasons for the Increase to Our Authorized Shares of Common Stock

The Board has determined, in its business judgment, that an increase to our authorized shares of common stock by approximately 35.7%49%, from 224,000,000304,000,000 shares to 304,000,000454,000,000 shares, is in the best interests of the Company and our stockholders, and as a result the Board has unanimously approved such an increase, subject to stockholder approval, and has unanimously recommended that our stockholders approve such an increase by voting in favor of this Proposal 5. In making this determination and approval, the Board considered, among other things: our agreement to issue and sellthe potential issuance of shares of our common stock to Total underupon exercise of the Purchase Agreement,Amazon Warrant as described in Proposal 4 above; our historical share issuance rates, as described below; anticipated future share requirements; guidelines and potential voting recommendations of third-party proxy advisory services, including Institutional Shareholder Services (“ISS”);Services; recent practices at other public companies; and a recommendation from our management.

The Board is requesting that our stockholders approve the increase to the authorized shares of our common stock in part to enable us to issue and sell 50,856,296 shares of our common stock to Total under the Purchase

Agreement for gross proceeds to us of $83.4 million. Pursuant to the Purchase Agreement, our ability to issue and sell all such shares is conditioned on and subject to our ability to obtain the approval of our stockholders of this Proposal 5 and our implementation of the increase to the authorized shares of our common stock described herein (although, as described in Proposal 4 above, Total would have the right to purchase a lesser number of shares of our common stock, if it elects to do so, if Proposal 4 or this Proposal 5 are not approved at the Annual Meeting). As described in Proposal 4 above, the Board believes the issuance and sale of all such shares to Total, as well as our other proposed relationships with Total, could provide meaningful capital resources and a valuable investor and partner in our execution offor our business plans and strategic initiatives. Please read Proposal 4 above for a fulsome description of the proposed share issuance to and other potential relationships with Total.

The Board is also requesting that our stockholders approve the increase to the authorized shares of our common stock to provide us with the flexibility to issue our common stock as needed for other purposes. The newly authorized shares of our common stock would be issuable for any proper corporate purpose, except for the portion thereof that we would issue and sell to Total under the Purchase Agreement, as described above, if our stockholders also approve Proposal 4 as described in this Supplement and certain other conditions are satisfied.purpose. Historically, we have issued our common stock (or securities convertible into or exercisable or exchangeable for our common stock) for the following main reasons:

Since January 2015,2019, we have issued common stock (or securities convertible into or exercisable or exchangeable for common stock) totaling 69,153,01858,206,062 shares (on a fully diluted basis) for the reasons described above, and our Board may desire to use our common stock for these or other reasons in the future. Of these shares, since January 2015,2019, we have issued shares of our common stock or granted equity awards in respect of shares of our common stock under our equity incentive plans for a total of 10,327,4937,610,531 shares (on a fully diluted basis), and the Board believes the availability of additional shares for future compensatory purposes is an important recruiting and retention tool.

Except with respect to the issuance of up to 50,856,296 shares of our common stock to Total under the Purchase Agreement, the issuance of shares of our common stock upon exercise of the conversion of outstanding convertible securities,Amazon Warrant (which we are asking our stockholders to approve in Proposal 4 and the issuance of shares of our common stock in connection with our employee stock purchase plan and equity compensation plans and awards granted thereunder, we currently have no specific understandings or commitments, oral or written, that would require us to issue a material amount of new shares of our common stock. In 2021, we anticipate deploying up to approximately $100.0 million to develop dairy RNG production projects and $45 million to $60 million to build fueling stations that will support RNG volume contracted to Amazon. If we deploy the foregoing capital, we will be required to raise significant additional capital during 2021, which may involve the issuance of a material amount of new shares of our common stock.

Possible Effects if Proposal 5 Is Approved

If this Proposal 5 is approved by our stockholders, the Board would generally be able to issue the additional authorized shares in its discretion from time to time without further action by or approval of our stockholders, subject to and as limited by any Nasdaqthe rules orand listing requirements of Nasdaq or any other then applicable securities exchange orand the requirements of all applicable law, and subject to our commitment to issue and sell up to 50,856,296 shares of our common stock to Total underupon exercise of the Purchase Agreement.Amazon Warrant.

Approval of this Proposal 5 could have the following effects:

However, stockholders should be aware that nothing would prevent the Board from taking any such actions that it deems consistent with its fiduciary duties.

Possible Effects if Proposal 5 Is Not Approved

If this Proposal 5 is not approved by our stockholders, then the number of shares of our common stock we would be authorized to issue would remain at its current amount of 224,000,000304,000,000 shares.

A failure to obtain the approval of our stockholders of this Proposal 5 could result in a lack of necessary flexibility to use equity for valid purposes. As described above, the Board believes this increase to the authorized shares of our common stock would provide us with needed flexibility to issue these shares in the future when and as necessary and on a timely basis, which would allow us to take advantage of market conditions, the availability of favorable financing and opportunities for acquisitions, in each case without the potential expense or delay incident to obtaining stockholder approval for each separate transaction or issuance. If this Proposal 5 is not approved by our stockholders, our Board would have significantly limited ability to issue equity at its discretion in the following effects:future, which could result in, among other things, difficulties retaining and recruiting executives and other personnel consistent with our business plans or an inability to effect potential future strategic or capital-raising transactions or acquisitions efficiently and when desired or otherwise believed to be advantageous to us.

Rights of Additional Authorized Shares of Common Stock

Any authorized shares of our common stock, if and when issued, would be part of our existing class of common stock and would have the same rights and privileges as the shares of common stock that are presently issued and outstanding.

Text and Effectiveness of the Increase to Our Authorized Shares of Common Stock

We propose to effectaffect the increase to the authorized shares of our common stock by amending the first two sentences of Article 4.A of our Restated Certificate of Incorporation to read in their entirety as follows:

“This corporation is authorized to issue two classes of stock to be designated, respectively, “Common Stock” and “Preferred Stock.” The total number of shares of stock which this corporation is authorized to issue is 305,000,000454,000,000 shares, 304,000,000453,000,000 of which shall be Common Stock with a par value of $.0001 per share, and 1,000,000 of which shall be Preferred Stock with a par value of $.0001 per share.”

The only change to the language of Article 4.A being voted on in this Proposal 54 is to increase the total number of shares of our common stock we may issue by approximately 35.7%49%, from 224,000,000304,000,000 shares to 304,000,000454,000,000 shares, and consequently the total number of shares of stock we may issue by the same amount. Other than as set forth above, our Restated Certificate as currently in effect would remain unchanged by the amendment to effectaffect the authorized share increase contemplated by this Proposal 5. Please note, however, that our Restated Certificate could also be amended to implement a reverse split of our common stock, which we are also requesting that our stockholders approve at the Annual Meeting and which is described in Proposal 6 of this Supplement below. As described in Proposal 6 below, if such a reverse split of our common stock is approved and implemented, the number of issued and outstanding shares of our common stock as well as the number of authorized shares of our common stock would be reduced, in each case by the ratio selected by the Board (please see the description of Proposal 6 below for more information). As a result, if this Proposal 5 is approved by our stockholders and Proposal 6 is also approved by our stockholders and such a reverse split of our common stock is implemented before or contemporaneously with the increase to the authorized shares of our common stock as contemplated by this Proposal 5, then the approval of this Proposal 5 will be deemed to be an approval by our stockholders of an increase to the authorized shares of our common stock by an amount equal to approximately 35.7% of the number of authorized shares of our common stock after giving effect to such reverse split of our common stock (which would result in a different number of authorized shares of our stock and our common stock than is set forth above, due to the impact of such a reverse split). See the tabular disclosure under “Effects of the Reverse Stock Split on our Common Stock” in Proposal 6 below for more information.

If this Proposal 5 is approved and adopted by our stockholders at the Annual Meeting, the increase to our authorized shares contemplated hereby would become effective upon our filing of a Certificate of Amendment to our Restated Certificate with the Secretary of State of the State of Delaware reflecting the amendments to Article 4.A thereof as set forth above, or at such other date and time as may be specified in the Certificate of Amendment. We expect to file such an amendment with the Secretary of State of the State of Delaware as soon as practicable following stockholder approval.

No Appraisal Rights

Under applicable Delaware law, our stockholders are not entitled to appraisal rights with respect to the proposed amendment to our Restated Certificate to increase the number of authorized shares of common stock we are authorized to issue.

Required Vote and Effect of Not Casting Your Vote

Proposal 5 must be approved by the affirmative vote of the holders of a majority of the issued and outstanding shares of our common stock entitled to vote on the proposal at the Annual Meeting. We expect that Proposal 5 constituteswill constitute a “routine” matter on which a broker, bank or other nominee is entitled to vote shares held for a beneficial owner even without receiving specific voting instructions from the beneficial owner. Generally, brokers, banks and other nominees will vote any such uninstructed shares in accordance with the recommendation of the Board. As a result, of the above, abstentions, if any, will have the same effect as a vote against this Proposal 5, and brokernon-votes are not expected to occur on Proposal 5.

OUR BOARD UNANIMOUSLY RECOMMENDS A VOTE “FOR” THE APPROVAL OF

AN AMENDMENT TO OUR RESTATED CERTIFICATE OF INCORPORATION

TO INCREASE THE AUTHORIZED SHARES OF OUR COMMON STOCK

common stock; prevailing market and economic conditions and trends; inputcontributions of our significant stockholders; recent practices at other public companies;employees, and we believe providing a competitive employee benefits program is one of our most important investments. As a result, we offer an employee benefits program with a wide range of plans designed to promote the health and personal welfare of all employees, including our named executive officers. Participation in these plans is generally available to all of our employees on the same basis. The Company provides minimal perquisites to executives which are noted in the description of “All Other Compensation” disclosed in the Summary Compensation Table on page 56.

Employment Agreements

We entered into employment agreements with each of our named executive officers on December 31, 2015. These employment agreements have the following key terms:

Other Compensation Policies

Executive Stock Ownership Guidelines

We believe it is important to encourage our named executive officers to hold a material amount of our common stock, which links their long-term economic interest directly to that of our stockholders. To achieve this goal, we have established stock ownership guidelines and potential voting recommendations of third-party proxy advisory services, including ISS; a recommendation fromapplicable to our management; andnamed executive officers. These guidelines provide that our agreementChief Executive Officer is required to issue and sellown shares of our common stock valued at three times his annual base salary or more, and each of our Chief Financial Officer, Chief Operating Officer, Chief Marketing Officer, Senior Vice President, Strategic Development, and Senior Vice President, Sales, in each case if any person is appointed in such position, is required to Total under the Purchase Agreement, as described in Proposal 4 above.

The Board is requesting that our stockholders approve, and grant the authority to the Board to determine whether to effect, a Reverse Stock Split primarily because it could improve the marketability and liquidityown shares of our common stock valued at one times his annual base salary or more. Such level of ownership must be attained by increasingthe later of December 14, 2019 and five years after the date of an executive officer’s initial appointment as such. Stock options are not counted toward satisfaction of these stock ownership requirements. Executives who attain the applicable stock ownership level by the stated deadline will continue to satisfy the stock ownership requirements if the value of their stock holdings declines after such deadline solely due to a decrease in the trading price of our common stock. Each of our named executive officers had satisfied these stock ownership guidelines as of the record date for the Annual Meeting.

Hedging and Pledging of Company Securities

Our policies do not permit any of our executive officers or directors to “hedge” ownership of our securities by engaging in short sales or trading in put options, call options or other derivatives involving our securities. This means that our employees and directors may not purchase financial instruments or otherwise engage in transactions that hedge or offset, or are designed to hedge or offset, any decrease in the market value of our equity securities. Further, our policies do not permit an executive officer or director to hold our securities in a margin account or pledge our securities as collateral for a loan unless the executive officer or director demonstrates to our satisfaction financial capacity to substitute other assets for Company securities in the event of a failure to meet a margin call or a default on the loan.

As of the date of this Proxy Statement, none of our directors or executive officers has pledged any of the shares of our common stock he or she owns.

Clawback Policy

The compensation committee has adopted a formal clawback policy regarding recoupment, or a “clawback,” of cash compensation in certain circumstances. The purpose of this clawback policy is to help ensure that executives act in the best interests of the Company and our stockholders. The clawback policy requires certain of our officers, including our named executive officers, to repay or return any cash incentive or other incentive cash compensation awarded to or received by such officer(s) in the event we issue a restatement of our financial statements due to material noncompliance with any financial reporting requirements and the restatement was caused by such officer’s fraud, intentional misconduct or gross negligence. In each case, the officer(s) would be required to repay or return the incentive cash compensation awarded to or received by the officer during the 12-month period following the filing of the erroneous financial statement at issue. Pursuant to the clawback policy, in the event of any restatement of our financial statements, the compensation committee would consider a number of factors and exercise its prevailing market price. business judgment in determining appropriate amounts, if any, to recoup. Further, the compensation committee retains the discretion to adjust or recover awards or payments if the relevant performance measures on which they are based are restated or are otherwise adjusted in a manner that would reduce the size of the award or payment. The clawback policy applies to cash compensation awarded to our officers from and after the date of its adoption.

Tax and Accounting Effects

In designing our compensation programs, the compensation committee considers the financial impact and tax and accounting effects that each element of compensation will or may have on the Company and our executives. One such area the compensation committee considers is the tax deductibility of each component of executive compensation. Prior to December 22, 2017, when the Tax Cuts and Jobs Act of 2017 (“TCJA”) was signed into law, Section 162(m) generally prohibited us from taking a tax deduction in any tax year for compensation paid to certain executive officers that exceeded $1,000,000, unless the compensation was payable only upon the achievement of pre-established, objective performance goals under a plan approved by our stockholders. As a result, we believe certain stock option, RSU and PVU awards we granted to our named executive officers before the impact of the TCJA have qualified as performance-based compensation under Section 162(m), although there is no guarantee that such equity awards, or any other performance-based compensation paid to our named executive officers, qualify as such. Under the TCJA, the exception for performance-based compensation under Section 162(m) has been repealed, so that the $1,000,000 limit on tax deductions in a tax year generally applies to anyone serving as our chief executive officer or our chief financial officer at any time during a taxable year as well as our top three other highest-compensated executive officers serving at fiscal year-end. These changes generally apply beginning in 2018, but generally do not apply to compensation provided pursuant to a binding written contract in effect on November 2, 2017 that is not modified in any material respect after that date. The compensation committee will continue to monitor developments under the TCJA, and will continue to consider steps that might be in our best interests to comply with Section 162(m), including after the impact from the TCJA. It is the compensation committee’s present intention to seek to structure executive compensation so that it will be deductible to the maximum extent permitted by applicable law, which means administering performance-based equity awards that were granted in 2017 or earlier in accordance with Section 162(m), as amended by the TCJA, in order to preserve their tax deductibility to the greatest extent possible; however, the compensation committee reserves the discretion to make any executive compensation decisions that it considers to be in the best interests of our Company and our stockholders, including to award compensation that may not be deductible or to amend existing compensation arrangements in a manner that could limit their deductibility.

COMPENSATION COMMITTEE REPORT

We, believe the current low per share marketcompensation committee of the Board of Clean Energy Fuels Corp., have reviewed and discussed the Compensation Discussion and Analysis (set forth above) with management of the Company, and based on such review and discussion, have recommended to the Board that the Compensation Discussion and Analysis be included in this Proxy Statement.

This compensation committee report shall not be deemed to be “soliciting material,” or to be “filed” with the SEC or subject to Regulation 14A or 14C under the Exchange Act, other than as provided by applicable SEC rules, or to the liabilities of Section 18 of the Exchange Act, except to the extent that we specifically request that the information be treated as soliciting material or specifically incorporate it by reference into a document filed under the Securities Act or the Exchange Act. This compensation committee report will not be deemed to be incorporated by reference into any filing under the Securities Act or the Exchange Act, except to the extent that we specifically incorporate it by reference.

EXECUTIVE COMPENSATION

Summary Compensation Table

The following table summarizes the total compensation awarded to, earned by or paid to each of our named executive officers for 2018, 2019 and 2020:

(1)   The amounts shown in this column represent the grant date fair value of awards granted in each of the periods calculated in accordance with Financial Accounting Standards Board’s Accounting Standards Codification Topic 718, “Compensation – Stock Compensation” (“FASB ASC 718”). For a discussion about the valuation models and assumptions used to calculate the fair value of these awards, see note 13 to the consolidated financial statements included in the Annual Report. The grant date fair value of the VVO awards granted in 2019 under FASB ASC 718 is the same at the maximum and probable performance levels.

(2)   The amounts shown in the Non-Equity Incentive Plan Compensation column represent the cash incentives paid under our performance-based cash incentive plan while the amounts shown in the Bonus column represent discretionary cash incentives paid for 2020 performance, each as described under “Compensation Discussion and Analysis—Components of Compensation—Cash Incentives” above.

(3)   The amounts shown in this column represent, (a) for all named executive officers, the Company’s matching contributions under its savings plan qualified under Section 401(k) of the Code, and (b) for Mr. Littlefair in 2020, $43,485 and $13,635 paid by the Company for life insurance premium and vehicle lease payments, respectively.

Grants of Plan-Based Awards

The following table summarizes all plan-based awards granted to each of the named executive officers in 2020: