Alternative fuel
Alternative fuels, for transportation applications, include the following:
methanol
denatured ethanol, and other alcohols
fuel mixtures containing 85 percent or more by volume of methanol, denatured ethanol, and other alcohols with gasoline or other fuels -- natural gas
liquefied petroleum gas (propane)
hydrogen
coal-derived liquid fuels
fuels (other than alcohol) derived from biological materials (biofuels such as soy diesel fuel)
electricity (including electricity from solar energy.)
"... any other fuel the Secretary determines, by rule, is substantially not petroleum and would yield substantial energy security benefits and substantial environmental benefits." The term "alternative fuel" does not include alcohol or other blended portions of primarily petroleum-based fuels used as oxygenates or extenders, i.e. MTBE, ETBE, other ethers, and the 10-percent ethanol portion of gasohol.