Outline of energy

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, energy is always equivalent to the ability to exert force against an object that is moving along a definite path of certain length.

Forms of energy

Gravitational energy – energy from gravitational fields
Ionization energy – energy that binds an electron to its atom or molecule
Kinetic energy –, energy of the motion of a body
Magnetic energy – energy from magnetic fields
Mechanical energy – The sum of kinetic and potential energies
Mechanical wave –, a form of mechanical energy propagated by a material's oscillations
Nuclear binding energy – energy that binds nucleons to form the atomic nucleus
Potential energy – energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors.
* Elastic energy – energy of deformation of a material exhibiting a restorative force
* Gravitational energy – potential energy associated with a gravitational field.
* Nuclear potential energy
Radiant energy –, energy of electromagnetic radiation including light and of gravitational radiation
Renewable energy – energy from renewable natural resources that are replenished on a human timescale
Rest energy – given by [Mass–energy equivalence|], where is an object's rest mass
Solar energy
Surface energy
Sustainable energy
Thermal energy – a microscopic, disordered equivalent of mechanical energy
* Heat – an amount of thermal energy being transferred in the direction of decreasing temperature
Work (physics) – an amount of energy being energy transferred in a given process due to displacement in the direction of an applied force
Electric power
Electricity

Measurement

Units

List of common units for energy. Official or common symbol in brackets after name and exact or approximate value of unit in joule in brackets after description.

SI unit

Joule – the SI-unit for energy. Also called newton meter, watt second, or coulomb volt.

Other metric units

Kilowatt-hour – corresponds to one kilowatt of power being used over a period of one hour.
Calorie – equal to the energy need to raise the temperature of one gram of water by one degree Celsius.
Erg – unit of energy and mechanical work in the centimetre-gram-second system of units.

Imperial or US Customary units

British thermal unit – equal to the energy need to raise the temperature of one pound of water by one degree Fahrenheit.
Therm – unit of heat energy. In the US gas industry it is defined as exactly 100,000 BTU_{59 °F}. It is approximately the heat equivalent of burning of natural gas.
Quad – unit of energy equal to 10¹⁵ BTU.
Foot-pound – unit of mechanical work, or energy, although in scientific fields one commonly uses joule.

Other units

Electronvolt – the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt.
Planck energy – natural unit of energy common in particle physics.
Barrel of oil equivalent – energy unit equal to the energy released when burning one barrel of oil.
Tonne of oil equivalent – energy unit equal to the energy released when burning one tonne of oil.

Related units and concepts

Volt
Ampere
Coulomb
Efficient energy use
Energy recovery
Energy recycling
Enthalpy
EU energy label
Fill factor – defined as the ratio of the maximum power divided by the short-circuit current and open-circuit voltage in light current density – voltage characteristics of solar cells.
Gigaton – Metric Unit of mass, equal to 1,000,000,000 metric tons, 1,000,000,000,000 kilograms
* Any of various units of energy, such as gigatons of TNT equivalent, gigatons of coal equivalent, gigatons petroleum equivalent.
Gray (unit) –, 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.
Heat
Mass–energy equivalence – where mass has an energy equivalence, and energy has a mass equivalence
Megawatt
Net energy gain
Power factor – of an AC electric power system is defined as the ratio of the real power to the apparent power.
Waste-to-energy
* Waste-to-energy plant
WattVoltage
Zero-energy building

Energy industry

Worldwide energy supply, outline by country/region
World energy resources and consumption
List of energy resources, substances like fuels, petroleum products and electricity
Energy crisis, the need to conserve energy resources
Energy development, development of energy resources — ongoing effort to provide abundant and accessible energy, through knowledge, skills and construction
Embodied energy, the sum total of energy expended to deliver a good or service as it travels through the economy
Energy conservation, tips for conserving energy resources
Energy economics, as the foundation of other relationships
Energy policy, government policies and plans for energy supply
Energy storage, methods commonly used to store energy resources for later use
Energy system, an interpretation the energy sector in system terms
Ecological energetics
Energy balance
Energy speculation
Free energy suppression conspiracy theory
Future energy development – Provides a general overview of future energy development.
History of perpetual motion machines
Hubbert peak theory, also known as peak oil – the theory that world oil production will peak, and will then rapidly decline, with a corresponding rapid increase in prices.
Primary production
Power harvesting
Renewable energy development

Energy infrastructure

See especially :Category:Electric power and :Category:Fuels for a large number of conventional energy related topics.

Energy applications

History of energy

Physics of energy

Energy
Activation energy, explains the differences in the speeds of various chemical reactions
Bioenergetics
Chemical energetics
Energy in physical cosmology
Energy in Earth science that is responsible for the macroscopic transformations on the planet Earth
Electricity
Exergy
Green energy
Orders of magnitude (energy), list describing various energy levels between 10⁻³¹ joules and 10⁷⁰ joules
Thermodynamics
Perpetual motion
Heat
History of energy
Forms of energy, the forms in which energy can be defined
Energy transformation, relating to energy's changes from one form to another.
Energy (signal processing), the inner product of a signal in the time domain
Energy density spectrum, relating to the distribution of signal energy over frequencies.
Potential energy, the form of energy that is due to position of an object
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, also salinity gradient power or blue energy, 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
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 energy required to strip an atom of an electron
Interaction energy, the contribution to the total energy that is a result of interaction between the objects being considered
Internal energy, the total kinetic energy due to the motion of molecules and the total potential energy associated with the vibrational and electric energy of atoms within molecules.
Negative energy
Energy conversion, process of converting energy from one form to another
Dark energy, used to explain some cosmological phenomena
Energy quality, empirical experience of the characteristics of different energy forms as they flow and transform
Energy density, amount of energy stored in a given system or region of space per unit volume, or per unit mass
Energy flow, flow of energy in an ecosystem through food chains
Energetics (disambiguation), the scientific study of energy in general
Stress–energy tensor, the density and flux of energy and momentum in space-time; the source of the gravitational field in general relativity
Food energy, energy in food that is available
Primary energy, energy contained in raw fuels and any other forms of energy received by a system as input to the system.
Radiant energy, energy that is transported by waves
Rotational energy, part of an object's total kinetic energy due to its rotation
Solar radiation, radiant energy emitted by the sun, particularly electromagnetic energy
Tidal power, also called tidal energy, is a form of hydropower that converts the energy of tides into useful forms of power – mainly electricity, dynamic tidal power, tidal lagoons, tidal barrages
Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work — for example, electricity generation, water desalination, or the pumping of water. Machinery able to exploit wave power is generally known as a wave energy converter.
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

Allegorical and esoteric

Energeticism, theory that there is no matter and everything is composed of energy
Energy (esotericism), invoked by spiritualists for alternative modes of healing the human body as well as a spirit that permeates all of reality.
Orgone, Wilhelm Reich discovered this energy and tried to use it to cure various physical ailments and control the weather.
Bioenergetic analysis, body-oriented Reichian psychotherapy
Qi, a concept from Oriental medicine that is sometimes translated as "energy" in the West.
Vitalism, often referred to as "energy"
Cold fusion, nuclear fusion at conditions close to room temperature.
Bubble fusion, also known as Sonofusion, energy from acoustic collapse of bubbles.
Water-fuelled car, powering a car using water as fuel.

Politics

Energy issues

2000 Watt society
Energy democracy
Environmental concerns with electricity generation
Fuel poverty
Greasestock, American showcase of vehicles and technologies powered by alternative energy
Low-carbon economy
Peak Oil
Soft energy path – an energy use and development strategy delineated and promoted by some energy experts and activists
Strategic Petroleum Reserve (disambiguation)

Energy policies and use – national and international

International

Energy policy – an introductory article
Energy and Environmental Security Initiative

Regional and national

Energy law – overview of many energy laws from various countries and states
* New York energy lawEnergy Tax Act – United States energy-related legislation. See also : :Category:United States federal energy legislation
United Kingdom:
* Energy policy of the United Kingdom
* Energy use and conservation in the United Kingdom

Economics

Energy economics

Energy companies

ExxonMobil
Enercon – Company based in Germany that operates in the wind turbine industry. One of the biggest producers in the world.
Saudi Aramco
Sasol
United States Enrichment Corporation – contracts with the United States Department of Energy to produce enriched uranium.

Non-profit organizations

Musicians United for Safe Energy

Industry associations

OPEC – Organization of Petroleum-exporting Countries
IEA – International Energy Agency
CAPP – Canadian Association of Petroleum Producers
World LP Gas Association – WLPGA

Innovators

Alessandro Volta
Charles Kettering
Farrington Daniels – solar energy
Georges Leclanché – battery
John Frederic Daniell – Daniell cell
Rudolf Diesel – compression ignition internal combustion engine
Georges Imbert – wood gas
Leonardo da Vinci
Moritz von Jacobi
Nicolaus Otto – internal combustion engine
Robert Stirling – Stirling engine
Nikola Tesla
James Watt – steam engine with separate condensor