; and (B) using the same water flow information used to determine a historic average annual generation baseline for the hydroelectric facility, as certified by the Commission. (6) Generation from mixed renewable and nonrenewable resources If electricity is generated using both a renewable energy resource and an energy source that is not a renewable energy resource (such as cofiring of renewable biomass and fossil fuel), the Commission shall issue Federal renewable electricity credits based on the proportion of the electricity generated that is attributable to the renewable energy resource. (7) Prohibition against double-counting The Commission shall ensure that— (A) no Federal renewable electricity credit is used more than once for compliance with this section; and (B) except as provided in paragraph (4), not more than 1 Federal renewable electricity credit is issued for any megawatt hour of renewable electricity generated. (8) Trading The lawful holder of a Federal renewable electricity credit may— (A) sell, exchange, or transfer the credit; (B) submit the credit for compliance under subsection (b)