When discussing energy, it is important to know how the Air Force defines energy and similar common terms.

Energy is any usable power, including, but not limited to, electricity and power produced from coal, petroleum products, steam,
natural gas, propane, military operational fuels and propellants, alternative fuels, and alternative and renewable energy sources, such
as solar, wind, geothermal, and nuclear.

Operational energy is energy required for training, moving, and sustaining military forces and weapons platforms for military
operations. The term includes energy used by tactical power systems, generators, and weapons platforms.

Process energy is energy directly consumed in manufacturing, maintenance, to include equipment overhaul, rehabilitation or
refurbishment, destruction, warehousing, and similar processes.

Renewable energy is energy produced by solar, wind, biomass, landfill gas, ocean (including tidal, wave, current, and thermal),
geothermal, municipal solid waste, or new hydroelectric generation capacity achieved from increased efficiency or additions of new
capacity at an existing hydroelectric project.

Energy security is assured access to reliable supplies of energy and the ability to protect and deliver sufficient energy to meet
operational needs

More definitions of key energy terms can be found in Appendix 2 of the Air Force Energy Strategic Plan.