(a) General Limitation on Use of Amounts.—A department, agency, or instrumentality of the Federal Government may not use amounts appropriated or made available by any law to purchase electricity in a manner inconsistent with state law governing the provision of electric utility service, including—
(b) Exceptions.—
(1) Energy savings.—
This section does not preclude the head of a federal agency from entering into a contract under section 801 of the National Energy Conservation Policy Act (42 U.S.C. 8287).