Outline of energy See also: Index of energy articles • Rest energy – (≥0) that E=mc² an object’s rest mass • Surface energy The following outline is provided as an overview of and topical guide to energy: • Thermal energy – a microscopic, disordered equiv- Energy – in physics, this is an indirectly observed quan- alent of mechanical energy tity often understood as the ability of a physical system to do work on other physical systems.[1][2] Since work is • Heat – an amount of thermal energy being defined as a force acting through a distance (a length of transferred (in a given process) in the direction space), energy is always equivalent to the ability to exert of decreasing temperature force (a pull or a push) against an object that is moving • along a definite path of certain length. Work (physics) – an amount of energy being energy transfer in a given Process (thermodynamic) due to displacement in the direction of an applied force 1 Forms of energy • Chemical energy – energy contained in molecules 2 Measurement • Electric energy – energy from electric fields 2.1 Units • Gravitational energy – energy from gravitational fields Main article: Units of energy • Ionization energy – energy that binds an electron to its atom or molecule • Barrel of oil equivalent (~6.1178632 × 109 J) • Kinetic energy – (≥0), energy of the motion of a • British thermal unit (~1055 J) body • • Magnetic energy – energy from magnetic fields Calorie (~4.184 J) • Mechanical energy – The sum of (usually • Current solar income – the amount of solar energy macroscopic) kinetic and potential energies that falls as sunlight • Mechanical wave – (≥0), a form of mechanical en- • Electronvolt – (symbol: eV) is the amount of en- ergy propagated by a material’s oscillations ergy gained by a single unbound electron when it falls through an electrostatic potential difference of • Nuclear binding energy – energy that binds nucleons one volt. (~1.602 × 10−19 J) to form the atomic nucleus • Planck energy, 1.22 × 1028 eV (1.96 × 109 J) • Potential energy – energy possessed by a body by virtue of its position relative to others, stresses • Erg – (symbol “erg”) unit of energy and mechanical [3][4] within itself, electric charge, and other factors. work in the centimetre-gram-second (CGS) system • Elastic energy – energy of deformation of a of units material (or its container) exhibiting a restora- • Foot-pound – (symbol ft·lbf or ft·lbf) is an Imperial tive force and U.S. customary unit of mechanical work, or en- • Gravitational energy – potential energy associ- ergy, although in scientific fields one commonly uses ated with a gravitational field. the equivalent metric unit of the joule (J). There are • Nuclear potential energy approximately 1.356 J/(ft·lbf). • Radiant energy – (≥0), energy of electromagnetic • Joule – (symbol J, also called newton meter, watt radiation including light second, or coulomb volt) 1 2 3 ENERGY INDUSTRY • Therm – (symbol thm) a non-SI unit of heat energy. 3 Energy industry It is approximately the heat equivalent of burning 100 cubic feet of natural gas. In the US gas in- Main article: Energy industry dustry it is defined as exactly 100,000 BTU₅₉ °F or 105.4804 megajoules. • Worldwide energy supply, outline by country/region • Kilowatt-hour – (symbol: kW·h) corresponds to one kilowatt (kW) of power being used over a period of • World energy resources and consumption one hour. • List of energy resources, substances like fuels, • Ton of oil equivalent petroleum products and electricity • TPE – Ton Petroleum Equivalent, 45.217 GJ, see • Energy crisis, the need to conserve energy resources ton of oil equivalent • Energy development, development of energy re- sources — ongoing effort to provide abundant and 2.2 Related units and concepts accessible energy, through knowledge, skills and construction • Volt • Embodied energy, the sum total of energy expended • Ampere to deliver a good or service as it travels through the economy • Coulomb • Energy conservation, tips for conserving energy re- • Enthalpy sources • • EU energy label Energy economics, as the foundation of other rela- tionships • Fill factor – defined as the ratio of the maximum • Energy policy, government policies and plans for en- power (Vmp x Jmp) divided by the short-circuit cur- ergy supply rent (Isc) and open-circuit voltage (Voc) in light cur- rent density – voltage (J-V) characteristics of solar • Energy storage, methods commonly used to store cells. energy resources for later use • Gigaton – Metric Unit of mass, equal • Energy system, an interpretation the energy sector to 1,000,000,000 (1 billion) metric tons, in system terms 1,000,000,000,000 (1 trillion) kilograms • Biosphere • Any of various units of energy, such as gi- gatons of TNT equivalent, gigatons of coal • Ecological energetics equivalent, gigatons petroleum equivalent. • Ecology • Gray (unit) – (symbol: Gy), is the SI unit of energy • for the absorbed dose of radiation. One gray is the Energy balance absorption of one joule of radiation energy by one • Earth Day kilogram of matter. One gray equals 100 rad, an older unit. • U4energy, a pan European school challenge on energy education launched in September 2010. • Heat U4energy is an initiative funded under the IEE pro- gramme to improve energy consumption in schools • Mass-energy equivalence – where mass has an en- and their local communities. ergy equivalence, and energy has a mass equivalence • Energy speculation • Megawatt • Free energy suppression • Net energy gain • Future energy development – Provides a general • Power factor – of an AC electric power system is overview of future energy development. defined as the ratio of the real power to the apparent power. • History of perpetual motion machines 3 • Hubbert peak theory, also known as peak oil – the • History of coal mining theory that world oil production will peak (or has • History of electricity peaked), and will then rapidly decline, with a corre- • sponding rapid increase in prices. History of the electric generator • History of the electric motor • Primary production • Timeline of the electric motor • Power harvesting • History of electric power transmission • History of nuclear power • Renewable energy development • History of petroleum • History of the petroleum industry 3.1 Energy infrastructure • History of renewable energy See especially Category:Electric power and Category: • History of alternative energy Fuels for a large number of conventional energy related • History of hydropower topics. • History of solar cells • Growth of photovoltaics • Energy storage • History of sustainability • Electricity generation • History of wind power • History of the steam engine • Electricity retailing • Steam power during the Industrial Revo- • Grid energy storage lution • Liquified natural gas • Microwave power transmission 5 Physics of energy • Power plant • Energy • Power supply • Activation energy explains the differences in the • Power transmission speeds of various chemical reactions • • Underground power station Alternative energy indexes • Bioenergetics 3.2 Energy applications • Chemical energetics • Biofuel • Energy in physical cosmology • Distributed generation • Energy in Earth science that is responsible for the macroscopic transformations on the planet Earth • Electric vehicle • Electricity • Hybrid vehicle • Exergy • Hydrogen vehicle • Green energy • Passive solar building design • Orders of magnitude (energy) – list describes var- • Steam engine ious energy levels between 10−31 joules and 1070 joules • 4 History of energy Thermodynamics • Perpetual motion Main article: History of energy • Heat • History of energy • History of the energy industry • Forms of energy, the forms in which energy can be • History of coal defined 4 5 PHYSICS OF ENERGY • Energy transformation, relating to energy’s changes • Dark energy, used to explain some cosmological from one form to another. phenomena • Energy (signal processing), the inner product of a • Energy quality, empirical experience of the charac- signal in the time domain teristics of different energy forms as they flow and transform • Energy density spectrum, relating to the distribution of signal energy over frequencies. • Energy density, amount of energy stored in a given system or region of space per unit volume, or per • Potential energy, the form of energy that is due to unit mass position of an object • Energy flow, flow of energy in an ecosystem through • Kinetic energy, the form of energy as a consequence food chains of the motion of an object or its constituents • Energetics, the scientific study of energy flows under • Mechanical energy, the potential energy and kinetic transformation energy present in the components of a mechanical system. • Stress–energy tensor, the density and flux of energy • Binding energy, a concept explaining how the con- and momentum in space-time; the source of the stituents of atoms or molecules are bound together gravitational field in general relativity • • Bond energy, a measure of the strength of a chemi- Food energy, energy in food that is available cal bond • Primary energy – Energy contained in raw fuels and • Nuclear energy, energy that is the consequence of any other forms of energy received by a system as decomposition or combination of atomic nuclei input to the system. • Osmotic power,or salinity gradient power and blue • Radiant energy – energy that is transported by waves energy, is the energy available from the difference • in the salt concentration between seawater and river Rotational energy – An object’s rotational energy