Alternative Fuel Definition – Internal Revenue Code

The Internal Revenue Service (IRS) defines alternative fuels as propane, natural gas, liquefied hydrogen, liquid fuel derived from coal through the Fischer-Tropsch process, liquid hydrocarbons derived from biomass, and P-Series fuels. Biodiesel, ethanol, and renewable diesel are not considered alternative fuels by the IRS. While the term “hydrocarbons” includes liquids that contain oxygen, hydrogen, and carbon and as such “liquid hydrocarbons derived from biomass” includes ethanol, biodiesel, and renewable diesel, the IRS specifically excluded these fuels from the definition.

(Reference 26 U.S. Code 6426)