Electricity generation 9540 225360944 2008-07-13T08:00:16Z Closedmouth 372693 Reverted edits by [[Special:Contributions/117.195.3.45|117.195.3.45]] to last version by Landon1980 (using [[WP:HG|Huggle]]) [[Image:Electricity production in the World.PNG|thumb|right|300px|World-wide electricity production for 1980 to 2005.]] '''Electricity generation''' is the process of converting non-electrical [[energy]] to [[electricity]]. For [[electric utility|electric utilities]], it is the first process in the delivery of electricity to consumers. The other processes, [[electric power transmission]] and [[electricity distribution]], are normally carried out by the [[electrical power industry]]. Electricity is most often generated at a [[power station]] by electromechanical [[electrical generator|generators]], primarily driven by [[heat engine]]s fueled by chemical [[combustion]] or [[nuclear fission]] but also by other means such as the kinetic energy of flowing water and wind. There are many other technologies that can be and are used to generate electricity such as solar [[photovoltaics]]. [[Image:Sources of electricity in the USA 2006.png|thumb|right|300px|Sources of electricity in the U.S. in 2006;<ref>[http://www.eia.doe.gov/cneaf/electricity/epa/epat1p1.html ''Net Generation by Energy Source by Type of Producer''], (c. 2006), accessed [[2008-03-28]], Washington: U.S. Dept. of Energy, Energy Information Administration.</ref> [[Fossil fuel power plant|fossil fuel generation]] (mainly coal) was the largest source.]] == History == [[Image:Sources of Electricity in France in 2006.PNG|thumb|right|300px|Sources of electricity in France in 2006;<ref>{{fr_icon}} {{cite web |author=DGEMP / Observatoire de l'énergie|year=April 2007|url=http://www.industrie.gouv.fr/energie/statisti/pdf/elec-analyse-stat.pdf|title=L’Electricité en France en 2006 : une analyse statistique.|accessdate=2007-05-23}}</ref> [[nuclear power]] was the main source.]] Centralized power generation became possible when it was recognized that [[alternating current]] power lines can transport [[electricity]] at very low costs across great distances by taking advantage of the ability to raise and lower the [[voltage]] using power [[transformer]]s. Electricity has been generated at central stations since 1881. The first power plants were run on [[Niagara Falls|water power]] or coal,<ref>[http://www.ieee-virtual-museum.org/collection/event.php?id=3456876&lid=1 Pearl Street Station: The Dawn of Commercial Electric Power]</ref> and today we rely mainly on [[coal]], [[nuclear power|nuclear]], [[natural gas]], [[hydroelectricity|hydroelectric]], and [[petroleum]] with a small amount from [[solar energy]], [[Tidal power|tidal harnesses]], [[wind generator]]s, and [[Geothermal power|geothermal]] sources. == Electricity demand == [[Image:Dreischluchtendamm hauptwall 2006.jpg|thumb|left|Large dams such as [[Three Gorges Dam]] in China can provide large amounts of [[hydroelectric]] power; it will have a 22.5 [[Watt|GW]] capability.]] [[Image:Grand Junction Trip 92007 098.JPG|thumb|right|Coal fired power plants provide 49% of consumed electricity in the United States. Cleaner burning technologies continue to make coal fired power one of the cheapest ways to generate electricity[http://www.netl.doe.gov/publications/press/2006/06046-Coal-Fired_Power_Plants_Database.html]. This is the Castle Gate Plant near [[Helper, Utah]].]] The demand for electricity is met in several ways. Large centralized generators have been the primary method thus far. [[Distributed generation]] uses a larger number of smaller generators throughout the electricity network. Some use waste heat from industrial processes, others use fuels that would otherwise be wasted, such as landfill gas. [[wind farm|Wind]] and [[solar energy|solar]] generation tend to be distributed because of the low density of the natural energy they collect. == Methods of generating electricity == Most electric generation is driven by [[heat engines]]. The combustion of fossil fuels supplies most of the heat to these engines, with a significant fraction from nuclear fission. === Turbines === Virtually all of the heat engines just mentioned are [[turbine]]s. Other types of turbines can be driven by wind or falling water. All turbines are driven by a fluid acting as an intermediate energy carrier. These fluids can be: [[Image:Susquehanna steam electric station.jpg|thumb|175px|left|[[Susquehanna Steam Electric Station]], a [[nuclear power plant]].]] * Steam - Water is boiled by [[nuclear fission]], the burning of [[Fossil fuel power plant|fossil fuels]] (coal, natural gas, or petroleum) or [[biomass]]. Some power plants use the sun as the heat source: [[solar parabolic trough]]s and [[solar power tower]]s concentrate sunlight to heat a heat transfer fluid, which is then used to produce steam. Another renewable source of heat used to drive a turbine is [[Geothermal power]]. Either steam under pressure emerges from the ground and drives a turbine or hot water evaporates a low boiling liquid to create vapour to drive a turbine. * Water (hydroelectric) - Turbine blades are acted upon by flowing water, produced by [[hydroelectric dam]]s or [[Tidal power|tidal forces]]. * Wind - Most [[wind turbine]]s generate electricity from naturally occurring wind. [[Solar updraft tower]]s use wind that is artificially produced inside the chimney by heating it with sunlight, and are more properly seen as forms of solar thermal energy. * Hot gas (gas turbine) - Turbines are driven directly by gases produced by the [[combustion]] of natural gas or oil. [[Image:Lakeside Power Plant.jpg|thumb|left|A combined cycle natural gas power plant near Orem, Utah.]] [[Combined cycle]] gas turbine plants are driven by both steam and gas. They generate power by burning natural gas in a [[gas turbine]] and use residual heat to generate additional electricity from steam. These plants offer efficiencies of up to 60%. === Reciprocating engines === [[Image:Mohave Generating Station 1.jpg|thumb|A coal-fired power plant in Laughlin, Nevada U.S.A. Owners of this plant ceased operations after declining to invest in pollution control equipment to comply with pollution regulations.<ref>{{cite news | author=Reuters News Service | title=Mohave Power Plant in Nevada to Close as Expected | date=2005-12-30 | publisher= | url =http://www.planetark.com/dailynewsstory.cfm/newsid/34265/story.htm | work =Planet Ark | pages = | accessdate = 2007-07-16 }}</ref>]] Small electricity generators are often powered by [[reciprocating engine]]s burning [[diesel]], [[biogas]] or natural gas. [[Diesel engines]] are often used for back up generation, usually at low voltages. Biogas is often combusted where it is produced, such as a landfill or wastewater treatment plant, with a reciprocating engine or a microturbine, which is a small gas turbine. === Photovoltaic panels === Unlike the solar heat concentrators mentioned above, [[Photovoltaics|photovoltaic panels]] convert sunlight directly to electricity. Although sunlight is free and abundant, solar electricity is still usually more expensive to produce than large-scale mechanically generated power due to the cost of the panels. Low-efficiency silicon solar cells have been decreasing in cost though, and multijunction cells with close to 30% conversion efficiency are now commercially available. Over 40% efficiency has been demonstrated in experimental systems.<ref>[http://www.doe.gov/news/4503.htm ''New World Record Achieved in Solar Cell Technology''] (press release, [[2006-12-05]]), U.S. Department of Energy.</ref> Until recently, photovoltaics were most commonly used in remote sites where there is no access to a commercial power grid, or as a supplemental electricity source for individual homes and businesses. Recent advances in manufacturing efficiency and photovoltaic technology, combined with subsidies driven by environmental concerns, have dramatically accelerated the deployment of solar panels. Installed capacity is growing by 40% per year led by increases in Germany, Japan, California and New Jersey. === Other generation methods === [[Image:Turbine aalborg.jpg|thumb|right|100px|[[Wind turbine|Wind-powered turbines]] usually provide electrical generation in conjunction with other methods of producing power.]] Various other technologies have been studied and developed for power generation. Solid-state generation (without moving parts) is of particular interest in portable applications. This area is largely dominated by [[thermoelectric effect|thermoelectric]] (TE) devices, though [[thermionic converter|thermionic]] (TI) and [[thermophotovoltaic]] (TPV) systems have been developed as well. Typically, TE devices are used at lower temperatures than TI and TPV systems. [[Piezoelectric]] devices are used for power generation from mechanical strain, particularly in [[power harvesting]]. [[Betavoltaics]] are another type of solid-state power generator which produces electricity from radioactive decay. Fluid-based [[MHD generator|magnetohydrodynamic]] (MHD) power generation has been studied as a method for extracting electrical power from [[nuclear reactors]] and also from more conventional fuel combustion systems. [[Electrochemistry|Electrochemical]] electricity generation is also important in portable and mobile applications. Currently, most electrochemical power comes from closed electrochemical cells ("[[Battery (electricity)|batteries]]") <ref>[http://www.eere.energy.gov/news/archive.cfm/pubDate=%7Bd%20'2003-09-24'%7D#6490 World's Largest Utility Battery System Installed in Alaska] (press release, [[2003-09-24]]), U.S. Department of Energy. ''"13,670 nickel-cadmium battery cells to generate up to 40 megawatts of power for about 7 minutes, or 27 megawatts of power for 15 minutes."''</ref>, which are arguably utilized more as storage systems than generation systems, but open electrochemical systems, known as [[fuel cells]], have been undergoing a great deal of research and development in the last few years. Fuel cells can be used to extract power either from natural fuels or from synthesized fuels (mainly electrolytic [[hydrogen]]) and so can be viewed as either generation systems or storage systems depending on their use. == Producers == [[Image:Electricity gen.JPG|thumb|right|Electricity output in 2005]] In 2005, USA continued to remain as the top producer of electricity with a global share of at least 25% followed by China, Japan and Russia. == See also == {{portal|Energy}} <div class="references-small" style="-moz-column-count:3; column-count:3;"> * [[Directive on Electricity Production from Renewable Energy Sources]] * [[Distributed generation]] * [[Emissions & Generation Resource Integrated Database (eGRID)]] * [[List of countries by electricity production from renewable source]] * [[Electric power transmission]] * [[Electric utility]] * [[Electricity distribution]] * [[Electricity retailing]] * [[Energy development]] * [[Environmental concerns with electricity generation]] * [[Eugene Green Energy Standard]] * [[Load profile]] * [[Mains electricity]] * [[Power quality]] * [[Virtual power plant]] * [[Voltage drop]] * [[World energy resources and consumption]] </div> == References == [[Image:Hoover dam from air.jpg|thumb|Large dams such as [[Hoover Dam]] can provide large amounts of [[hydroelectric]] power; it has a 2.07 gigawatt capability.]] <References/> == External links == * [http://www.nrel.gov/analysis/power_databook/ Power Technologies Energy Data Book] * [http://www.spectrum.ieee.org/apr08/6182 IEEE Spectrum: How Much Water Does It Take to Make Electricity?] -- Natural gas requires the least water to produce energy, biofuels the most, according to a new study [[Category:Electricity distribution]] [[Category:Electric power]] [[Category:Electricity market]] [[ar:توليد كهرباء]] [[de:Stromerzeugung]] [[es:Generación de energía eléctrica]] [[fa:تولید انرژی الکتریکی]] [[fr:Production d'électricité]] [[it:Produzione di energia elettrica]] [[he:ייצור חשמל]] [[ja:発電]] [[pt:Geração de eletricidade]] [[ru:Генерация электроэнергии]] [[simple:Electricity generation]] [[fi:Sähköntuotanto]] [[sv:Elproduktion]] [[vi:Sản xuất điện năng]] [[wa:Produjhaedje di corant]] [[zh:發電方式]]