Alternative Fuel Vehicles

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Vehicle Conversions

Conversions allow vehicles that were originally designed to operate on gasoline or diesel to run on an alternative fuel, providing a valuable option for moving to alternative fuels.  Compressed natural gas (CNG) and propane (LPG) conversions are the most common although conversions are currently rare. It is now possible to purchase certain natural gas and propane vehicles that have been up-fit at a central facitlity. These vehicles are usually sold through existing car dealers and appear to the user almost as factory-built vehicles.

For a detailed explanation of all things relating to conversions of natural gas vehicles, please see this FAQ document from NGVAmerica. The document includes sections on:

• availability
• installation
• service & warranty
• cost & tax credits
• fueling

Under the federal Clean Air Act (CAA), removing or tampering with emissions control devices on vehicles is a violation of the act.  The U.S. Environmental Protection Agency (EPA) has issued a series of regulations and procedures under which alternative fuel conversions can be performed in compliance with the CAA, establishing emissions standards and testing procedures for CNG and LPG vehicles. Early regulations consisted of Mobile Source Enforcement Memorandum 1A (Memo 1A), as well as the Addendum to Memo 1A, and the Revision to the Addendum to Memo 1A. These have since been superceded by more recent EPA regulations.

EPA now certifies converted vehicles, rather than conversion systems or "kits."  An aftermarket conversion may only be performed on a vehicle if a Certificate of Conformity or a CARB certification has been issued for that vehicle's particular model year and exhaust and evaporative emissions test groups. An individual or entity wishing to have a vehicle converted must do so through a company or organization associated with a certificate holder. Examples of types of companies or organizations that hold Certificates of Conformity issued by EPA include the designer of the conversion equipment, the producer or manufacturer of the equipment, and the person or entity that plans to perform installations.

The U.S. Department of Energy provides additional information on vehicle conversions, including a list of conversion company industry contacts.