alternate fuel
(6) The term “alternate fuel” means electricity or any fuel, other than natural gas or petroleum, and includes— (A) petroleum coke, shale oil, uranium, biomass, and municipal, industrial, or agricultural wastes, wood, and renewable and geothermal energy sources; (B) liquid, solid, or gaseous waste byproducts of refinery or industrial operations which are commercially unmarketable, either by reason of quality or quantity, as determined under rules prescribed by the Secretary; and (C) waste gases from industrial operations.