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.