The following outline is provided as an overview of and topical guide to energy:
Energy – in physics, this is an indirectly observed quantity often understood as the ability of a physical system to do work on other physical systems. Since work is defined as a force acting through a distance (a length of space), energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of a certain length.
Fill factor – defined as the ratio of the maximum power (Vmp x Jmp) divided by the short-circuit current (Isc) and open-circuit voltage (Voc) in light current density – voltage (J-V) characteristics of solar cells.
Foot-pound – (symbol ft·lbf or ft·lbf) is an Imperial and U.S. customary unit of mechanical work, or energy, although in scientific fields one commonly uses the equivalent metric unit of the joule (J). There are approximately 1.356 J/(ft·lbf).
Gigaton – Metric Unit of mass, equal to 1,000,000,000 (1 billion) metric tons, 1,000,000,000,000 (1 trillion) kilograms
Any of various units of energy, such as gigatons of TNT equivalent, gigatons of coal equivalent, gigatons petroleum equivalent.
Gray (unit) – (symbol: Gy), is the SI unit of energy for the absorbed dose of radiation. One gray is the absorption of one joule of radiation energy by one kilogram of matter. One gray equals 100 rad, an older unit.
Power factor – of an AC electric power system is defined as the ratio of the real power to the apparent power.
Therm – (symbol thm) a non-SI unit of heat energy. It is approximately the heat equivalent of burning 100 cubic feet of natural gas. In the US gas industry it is defined as exactly 100,000 BTU59°F or 105.4804 megajoules.
Kinetic energy, the form of energy as a consequence of the motion of an object or its constituents
Mechanical energy, the potential energy and kinetic energy present in the components of a mechanical system.
Binding energy, a concept explaining how the constituents of atoms or molecules are bound together
Bond energy, a measure of the strength of a chemical bond
Nuclear energy, energy that is the consequence of decomposition or combination of atomic nuclei
Osmotic power,or salinity gradient power and blue energy, is the energy available from the difference in the salt concentration between seawater and river water
Gibbs free energy, a related concept in chemical thermodynamics that incorporates entropy considerations too
Helmholtz free energy, a thermodynamic potential that measures the "useful" work obtainable from a closed thermodynamic system at a constant temperature, useful for studying explosive chemical reactions
Elastic energy, which causes or is released by the elastic distortion of a solid or a fluid
Ionization energy – the (IE) of an atom is the energy required to strip it of an electron.
Interaction energy, the contribution to the total energy that is a result of interaction between the objects being considered
Internal energy – (abbreviated E or U) the total kinetic energy due to the motion of molecules (translational, rotational, vibrational) and the total potential energy associated with the vibrational and electric energy of atoms within molecules.
Wind energy is the kinetic energy of air in motion;Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, windmills for mechanical power, windpumps for water pumping or drainage, or sails to propel ships
U4energy, a pan European school challenge on energy education launched in September 2010. U4energy is an initiative funded under the IEE programme to improve energy consumption in schools and their local communities.