Fuel

Fuel is any solid, liquid or gaseous substance or material that can be combined with an oxidant (also known as an oxidizer or combustion agent) during combustion reactions. This reaction generates large amounts of heat. The oxidant is usually the oxygen in the air. By extension and although it is in no way a combustion reaction, the term "nuclear fuel" is used to designate the fissile materials used to produce fission energy in nuclear power plants.