Fuel

Fuels are ony materials that store potential energy in forms that can be practicably released an uised as heat energy. The concept originally applied solely tae those materials storin energy in the form o chemical energy that could be released through combustion,^[1] but the concept haes syne been an aa applied tae other soorces o heat energy such as nuclear energy (via nuclear fission or nuclear fusion), as well as releases o chemical energy released through non-combustion oxidation (such as in cellular biology or in fuel cells).