Alternative Fuel Sources under 42 U.S.C. § 6374(a)(3)(F) says that at least 50% of the alternative fuels used in vehicles is to be derived from domestic feedstocks.
At least 50% of the alternative fuels used in vehicles acquired pursuant to this section shall be derived from domestic feedstocks, except to the extent inconsistent with the multilateral trade agreements (as defined in section 3501 (4) of title 19). The Secretary shall issue regulations to implement this requirement. For purposes of this subparagraph, the term "domestic" has the meaning given such term in section 13211 (7) of this title.