EPA proposes to streamline approval process for fuel conversion systems

The US Environmental Protection Agency (EPA) is proposing to make it easier for manufacturers to gain approval to sell fuel conversion systems. Conversion systems allow vehicles to run on alternative fuels; most conversions involve switching gasoline or diesel vehicles to operate instead on a gaseous fuel such as natural gas or propane; an alcohol fuel; or electricity.

The new options would reduce some economic and procedural impediments to clean alternative fuel conversions while maintaining environmental safeguards to ensure that acceptable emission levels from converted vehicles are sustained. The proposed rule would cover conversions of light-duty vehicles and heavy-duty highway vehicles and engines, and would apply to all clean alternative fuels.

While properly engineered conversion systems can reduce or at least not increase emissions, poorly designed systems can lead to much more pollution. Current EPA regulations require vehicle and engine conversion systems to be covered by a certificate of conformity to gain a regulatory exemption from potential tampering charges.

EPA evaluated this requirement and believes it is appropriate to introduce new flexibilities for all clean alternative fuel converters and expand the compliance options in certain conversion situations. Under the proposed approach, compliance requirements would vary based on age of the vehicle or engine being converted.


All conversion manufacturers would need to demonstrate compliance with EPA requirements, but the requirements would differ among age categories. EPA expects the streamlined approach to result in a cost savings for many converters.

Key elements of the proposed rulemaking. The proposed compliance program would enable conversion manufacturers to qualify for an exemption when they demonstrate that the converted vehicle or engine satisfies EPA emissions requirements.


  • The notification and demonstration requirements for new and nearly new vehicles and engines would remain very similar to current certification requirements.
  • The requirements for intermediate age vehicles and engines would involve testing and submission of data to show that the converted vehicle or engine continues to meet applicable standards.
  • EPA is seeking comment on three possible demonstration options for vehicles and engines that have exceeded their regulatory useful life.

Outside useful life vehicles and engines. The outside useful life age category would cover vehicles/engines that have exceeded their regulatory useful life. The proposal seeks comment on three options for the outside useful life compliance demonstration, with the intent to finalize one demonstration requirement:

  1. Manufacturers would submit a sufficiently detailed description to show that the conversion technology is technically sound and is applied according to principles of good engineering judgment.
  2. Manufacturers would conduct testing as in the intermediate age program and submit data to show that either a) the converted vehicle or engine is able to meet standards applicable inside useful life, or b) emissions do not increase after conversion.
  3. Manufacturers would submit a technical description as in Option 1, and also an OBD scan report from the converted vehicle or engine to show that the OBD system continues to function properly.

The notification requirement, as for the intermediate age program, would involve submitting the required information, data, and/or OBD attestations to EPA. Converters would be permitted further flexibilities for expanded test groups. No certificate would be issued, and annual re-certification would not be required.

EPA will accept public comments on this proposal until 23 July, 2010.

- Green Car Congress staff


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