UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM SD

Specialized Disclosure Report

CLEAN ENERGY FUELS CORP.

(Exact Name of Registrant as Specified in Charter)

J. Nathan Jensen

Senior Vice President, Corporate Transactions and Chief Legal Officer

Clean Energy Fuels Corp.

4675 MacArthur Court, Suite 800

Newport Beach, California 92660

(949) 437-1000

(Name and Telephone Number, including Area Code,

of the Person to Contact in Connection with This Report.)

Check the appropriate box to indicate the rule pursuant to which this form is being filed, and provide the period to which the information in this form applies:

Section 1 — Conflict Minerals Disclosure

Conflict Minerals Disclosure

This Form SD of Clean Energy Fuels Corp. (the “Company”) is filed pursuant to Rule 13p-1 promulgated under the Securities Exchange Act of 1934 for the reporting period from January 1, 2018 to December 31, 2018 (the “Reporting Period”).

A copy of the Company’s Conflict Minerals Report for the Reporting Period is filed as Exhibit 1.01 to this Form SD, is hereby incorporated by reference herein, and is publicly available at http://investors.cleanenergyfuels.com/corporate-governance.cfm. The foregoing website reference is intended to be an inactive textual reference, and the contents of the Company’s website are not incorporated into this Form SD.

Item 1.02 Exhibit.

The Conflict Minerals Report required by Item 1.01 of Form SD is filed as Exhibit 1.01 to this Form SD.

Section 2 — Exhibits

Item 2.01 Exhibits

1

EXHIBIT INDEX

2

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the duly authorized undersigned.

3

Exhibit 1.01

CLEAN ENERGY FUELS CORP.

Conflict Minerals Report

For the Reporting Period from January 1, 2018 to December 31, 2018

This Conflict Minerals Report (the “Report”) of Clean Energy Fuels Corp. (together with its consolidated subsidiaries, the “Company”) has been prepared pursuant to Rule 13p-1 and Form SD (collectively, the “Rule”) promulgated under the Securities Exchange Act of 1934, as amended, for the reporting period from January 1, 2018 to December 31, 2018 (the “Reporting Period”). As permitted by applicable guidance of the Securities and Exchange Commission, the Company did not obtain an independent private sector audit within the meaning of the Rule.

Overview of the Company and the Rule

The Company is the leading provider of natural gas as an alternative fuel for vehicle fleets in the United States and Canada, based on the number of stations operated and the amount of gasoline gallon equivalents (“GGEs”) of renewable natural gas (“RNG”), compressed natural gas (“CNG”) and liquefied natural gas (“LNG”) delivered. The Company’s principal business is supplying RNG, CNG and LNG (RNG can be delivered in the form of CNG or LNG) for light, medium and heavy-duty vehicles and providing operation and maintenance (“O&M”) services for vehicle fleet customer stations. As a comprehensive solution provider, the Company also designs, builds, operates and maintains fueling stations; sells and services natural gas fueling compressors and other equipment used in CNG stations and LNG stations; offers assessment, design and modification solutions to provide operators with code-compliant service and maintenance facilities for natural gas vehicle fleets; transports and sells CNG and LNG via “virtual” natural gas pipelines and interconnects; procures and sells RNG; sells tradable credits it generates by selling RNG and conventional natural gas as a vehicle fuel, including Renewable Identification Numbers under the federal Renewable Fuel Standard Phase 2 and credits under the California and Oregon Low Carbon Fuel Standards; helps its customers acquire and finance natural gas vehicles; and obtains federal, state and local tax credits, grants and incentives. As of March 31, 2019, the Company served over 1,000 fleet customers operating over 47,000 natural gas vehicles, and the Company owned, operated or supplied approximately 530 natural gas fueling stations in 41 states in the United States and four provinces in Canada.

The Rule requires disclosure of certain information if a company manufactures or contracts to manufacture products for which the minerals specified in the Rule are necessary to the functionality or production of the products. The Rule also requires such companies to conduct certain inquiries reasonably designed to determine whether such minerals originated in the countries specified in the Rule. The minerals specified in the Rule, which are collectively referred to in this Report as the “Conflict Minerals,” consist of gold, columbite-tantalite (coltan), cassiterite and wolframite, including their derivatives, which are limited to tantalum, tin and tungsten. The countries specified in the Rule, which are collectively referred to in this Report as the “Covered Countries,” consist of the Democratic Republic of the Congo and all countries that share an international border with the Democratic Republic of the Congo, which presently consists of the Republic of the Congo, the Central African Republic, South Sudan, Uganda, Rwanda, Burundi, Tanzania, Zambia and Angola. As described in this Report, certain aspects of the Company’s operations involve the manufacture, or contracting for manufacture, of products for which the Conflict Minerals are necessary to the functionality or production of the products.

When this Report uses the term “Conformant,” it means the applicable mine, smelter or refiner has been verified as complying with the Responsible Minerals Assurance Process (“RMAP,” formerly the Conflict-Free Smelter Program or CFSP) of the Responsible Mining Initiative (“RMI,” formerly the Conflict-Free Sourcing Initiative or CFSI) or an equivalent third-party audit program, and when this Report uses the term “Active,” it means the applicable mine, smelter or refiner has agreed to participate in the RMAP but has not yet completed the program to become Conformant.

The Company’s Products Covered by this Report

This Report covers products: (i) for which one or more Conflict Minerals is necessary to the functionality or production of the product; (ii) that were manufactured, or contracted to be manufactured, by the Company; and (iii) for which the manufacture was completed during the Reporting Period. These products, which are collectively referred to in this Report as the “Covered Products,” consist of the following:

Third-party products the Company sells at retail but does not manufacture or contract to manufacture are outside the scope of this Report.

Overview of the Company’s Supply Chain

The Company’s supply chain with respect to the Covered Products is complex, and there are many third parties in the supply chain between the original sources of Conflict Minerals and the ultimate manufacture of the Covered Products. In this regard, the Company does not purchase Conflict Minerals directly from mines, smelters or refiners. The Company must therefore rely on its suppliers to provide information regarding the origin of Conflict Minerals that are necessary to the functionality or production of the Covered Products. Moreover, the Company believes the mines, smelters and refiners of the Conflict Minerals are best situated to identify the sources of Conflict Minerals, and therefore the Company has sought to identify the applicable mines, smelters and refiners of Conflict Minerals in the Company’s supply chain.

The Company’s Conflict Minerals Policy

The Company maintains a policy relating to the sourcing of Conflict Minerals (the “Company Policy”), which provides as follows:

The Company has designed its Conflict Minerals reporting efforts, including the design and implementation of the Company Policy, to align and comply with the Rule. The full text of the Company Policy is available at http://investors.cleanenergyfuels.com/corporate-governance.cfm. The foregoing website reference and all other such references in this Report are intended to be inactive textual references, and the contents of the Company’s website are not intended to be incorporated into this Report.

The Company’s Reasonable Country of Origin Inquiry

The Company has conducted in good faith a reasonable country of origin inquiry (“RCOI”) regarding the Conflict Minerals. This RCOI was reasonably designed to determine whether any of the Conflict Minerals necessary to the functionality or production of a Covered Product originated in the Covered Countries or may be from recycled or scrap sources. Based on the RCOI, the Company has reason to believe that some of the necessary Conflict Minerals contained in the Covered Products may have originated from the Covered Countries or may not be from recycled or scrap sources. As a result, the Company exercised due diligence on the source and chain of custody of such Conflict Minerals, as described below.

Due Diligence Process

Due diligence process design

The Company’s due diligence measures have been designed to conform, in all material respects, to the framework in the Organisation for Economic Co-operation and Development Due Diligence Guidance for Responsible Supply Chains of Minerals from Conflict-Affected and High Risk Areas: Third Edition (2016), including the related supplements on gold, tin, tantalum and tungsten (collectively, the “OECD Guidance”).

Due diligence performed

Below is a summary of the Company’s due diligence process performed in the Reporting Period regarding the sourcing of the necessary Conflict Minerals contained in the Covered Products. The description below is intended to provide a summary of the Company’s due diligence process, and thus the measures described below are not the only measures the Company took in the Reporting Period in furtherance of the Company Policy or pursuant to the Rule and the OECD Guidance.

OECD Guidance Step 1: Maintain a management system

OECD Guidance Step 2: Identify and assess risks

OECD Guidance Step 3: Design and implement strategy to respond to risk

OECD Guidance Step 4: Carry out independent third-party audits of the supply chain

OECD Guidance Step 5: Report on supply chain due diligence

Results of Due Diligence Performed

The Company’s efforts to determine the mine or location of origin of the necessary Conflict Minerals contained in the Covered Products with the greatest possible specificity consisted primarily of the due diligence measures described in this Report. The Company received responses from 72% of its identified in-scope suppliers.

Based on the information provided by the Company’s suppliers, and taking into account the supplier responses described in the preceding paragraph, the Company believes the facilities that may have been used to process the necessary Conflict Minerals contained in the

Covered Products include the processing facilities listed in Tables 1, 2 and 3 in Appendix A to this Report. Of the 300 processing facilities identified by the Company’s suppliers as being in the supply chain for the Covered Products, 249 have been validated as Conformant, four have been confirmed as Active, and 47 have not been confirmed as Conformant or Active.

Based on its due diligence efforts, the Company does not have sufficient information to conclusively determine the countries of origin of the Conflict Minerals in the Covered Products. Based on the information provided by the Company’s suppliers, however, the Company has reason to believe that some of the necessary Conflict Minerals contained in the Covered Products may have originated from the Covered Countries or may not be from recycled or scrap sources.

Additional Future Measures

The Company aims to take the following steps, among others, to improve its due diligence measures and to further mitigate the risk that the necessary Conflict Minerals contained in the Covered Products finance or benefit armed groups (perpetrators of serious human rights abuses) in the Covered Countries:

Inherent Limitations on Due Diligence Measures

As a downstream purchaser of products that contain Conflict Minerals, the Company’s due diligence measures can provide only reasonable, not absolute, assurance regarding the source and chain of custody of the necessary Conflict Minerals contained in the Covered Products. The supply chain of commodities such as the Conflict Minerals is a complex and multi-step process that involves a number of different parties. Because the Company does not have direct contractual relationships with mines, smelters and refiners, its due diligence processes must rely on information provided by its direct suppliers, as well as similar information provided to those suppliers within their supply chains, to identify the original sources of the necessary Conflict Minerals contained in the Covered Products. The results of the Company’s due diligence efforts could contain inaccuracies or incomplete information due to this process of collecting information. Further, many suppliers’ responses represent the supply chain at a company-level rather than being product-specific, and as a result, the list of processing facilities disclosed in this Report may contain facilities that did not actually process the Conflict Minerals contained in the Covered Products. In addition, the Company relies on information collected and provided by independent third-party audit programs, such as the RMAP of the RMI, and these sources of information may yield unreliable, inaccurate or incomplete information due to a variety of factors, including human or other errors or fraudulent actions.

Forward-Looking Statements

This Report contains forward-looking statements regarding the Company’s business, products and Conflict Minerals efforts, including steps the Company intends to take to improve its due diligence measures. Words such as “expects,” “believes,” “aims” and similar expressions or variations of such words are intended to identify forward-looking statements, but are not the exclusive means of identifying forward-looking statements in this Report. All statements made in this Report concerning future matters that are not historical in nature are forward-looking statements. Although forward-looking statements in this Report reflect the Company’s good faith judgment, such statements can only be based on facts and assumptions currently known by the Company. Consequently, forward-looking statements are inherently subject to risks and uncertainties, and actual results and outcomes may differ materially from the results and outcomes discussed in or anticipated or implied by the forward-looking statements. Factors that could cause or contribute to such differences in results and outcomes include, among others: the risk that information reported to the Company by its suppliers, or other industry information used by the Company, may be inaccurate; the risk that mines, smelters or refiners may not participate in the RMAP or equivalent third-party audit programs, which are voluntary initiatives; and risks related to the Company’s compliance with government regulations and policies, which, among other risks, are discussed under “Risk Factors” in the Company’s most recent annual report on Form 10-K and the other filings it makes with the U.S. Securities and Exchange Commission from time to time, including any subsequently filed quarterly and current reports. Forward-looking statements are not predictions of future events, and readers should not rely on them as such. All forward-looking statements included in this Report speak only as of the date of this Report, and the Company undertakes no obligation to revise or update any forward-looking statements in order to reflect any event or circumstance that may arise after the date of this Report.

Appendix A

Tables of Our Conflict Minerals Processing Facilities

Table 1. Conformant processing facilities as of March 7, 2019.

The following processing facilities that were reported as being in the Company’s supply chain have been validated as Conformant:

A-1

A-2

A-3

A-4

A-5

A-6

A-7

A-8

A-9

A-10

Table 2. Active processing facilities as of March 7, 2019.

The following processing facilities that were reported as being in the Company’s supply chain have been confirmed as Active:

Table 3. Processing facilities not Conformant or Active as of March 7, 2019.

The following processing facilities that were reported as being in the Company’s supply chain have not been confirmed as Conformant or Active:

A-11

A-12

A-13

A-14