No Federal agency shall enter into a contract for procurement of an alternative or synthetic fuel, including a fuel produced from nonconventional petroleum sources, for any mobility-related use, other than for research or testing, unless the contract specifies that the lifecycle greenhouse gas emissions associated with the production and combustion of the fuel supplied under the contract must, on an ongoing basis, be less than or equal to such emissions from the equivalent conventional fuel produced from conventional petroleum sources.
42 U.S. Code § 17142 - Procurement and acquisition of alternative fuels
Waiver Authority for Alternative Fuel Procurement Requirement
“(a) In General.—
“(b) Notification Requirement.—
The Secretary of Defense shall notify the congressional defense committees [Committees on Armed Services and Appropriations of the Senate and the House of Representatives] not later than 15 days after exercising the waiver authority under subsection (a).”