(1) For the purposes of this section: (a) Alcohol fuel means any alcohol made from a product other than petroleum or natural gas, which is used alone or in combination with gasoline or other petroleum products for use as a fuel for motor vehicles, farm implements, and machines or implements of husbandry. (b) Anaerobic digester has the same meaning as provided in RCW 82.08.900. (c) Biodiesel f