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[[File:Pretty flamingos - geograph.org.uk - 578705.jpg|thumb|upright=1|[[Burbo Bank Offshore Wind Farm]], at the entrance to the [[River Mersey]] in North West England.]]
[[File:Shepherds Flat Wind Farm 2011.jpg|thumb|The [[Shepherds Flat Wind Farm]] is a 845 [[megawatt]] (MW) [[wind farm]] in the U.S. state of [[Oregon]].]]
{{Renewable energy sources}}
{{Sustainable energy}}
'''Wind power''' is the conversion of [[wind]] [[energy]] into a useful form of energy, such as using [[wind turbine]]s to make [[electrical power]], [[windmill]]s for mechanical power, [[windpump]]s for [[water pumping]] or [[drainage]], or [[sail]]s to propel [[Sailing ship|ships]].
 
Large [[wind farm]]s consist of hundreds of individual wind turbines which are connected to the [[electric power transmission]] network. For new constructions, onshore wind is an inexpensive source of electricity, competitive with or in many places cheaper than fossil fuel plants.<ref name="businessgreen" /> {{citation needed|date=September 2013}} Small onshore wind farms provide electricity to isolated locations. Utility companies increasingly [[Net metering|buy surplus electricity]] produced by small domestic wind turbines.<ref name="Wind Energy">{{cite journal|last=Gipe|first=Paul|title=The Wind Industry's Experience with Aesthetic Criticism|journal=Leonardo|jstor=1575818|volume= 26|issue=3 |year=1993|pages=243–248|doi=10.2307/1575818}}</ref> Offshore wind is steadier and stronger than on land, and offshore farms have less visual impact, but construction and maintenance costs are considerably higher.
 
Wind power, as an alternative to [[fossil fuel]]s, is plentiful, [[renewable energy|renewable]], widely distributed, [[Sustainable energy|clean]], produces no [[greenhouse gas]] emissions during operation and uses little land.<ref name="landuse">{{cite doi|10.1016/j.rser.2008.09.017}}</ref> The [[Environmental impact of wind power|effects on the environment]] are generally less problematic than those from other power sources. As of 2011, [[Wind power in Denmark|Denmark is generating]] more than a quarter of its electricity from wind and 83 countries around the world are using wind power to supply the electricity grid.<ref name=ren212011 /> In 2010 wind energy production was over 2.5% of total worldwide electricity usage, and growing rapidly at more than 25% per annum.
 
Wind power is very consistent from year to year but has significant variation over shorter time scales. As the proportion of windpower in a region increases, a need to upgrade the grid, and a lowered ability to supplant conventional production can occur.<ref name="ieawind" /><ref name=abbess /> Power management techniques such as having excess capacity storage, geographically distributed turbines, dispatchable backing sources, storage such as [[pumped-storage hydroelectricity]], exporting and importing power to neighboring areas or reducing demand when wind production is low, can greatly mitigate these problems.<ref name="eirgrid impact" /> In addition, [[weather forecast]]ing permits the electricity network to be readied for the predictable variations in production that occur.<ref>Platt, Reg (21 January 2013) [http://www.newscientist.com/article/mg21729000.200-wind-power-delivers-too-much-to-ignore.html Wind power delivers too much to ignore], ''[[New Scientist]]''.</ref><ref>Platt, Reg; Fitch-Roy, Oscar and Gardner, Paul (August 2012) [http://www.ippr.org/images/media/files/publication/2012/08/beyond-the-bluster_Aug2012_9564.pdf Beyond the Bluster why Wind Power is an Effective Technology]. Institute for Public Policy Research.</ref>
 
== History ==
{{Main|History of wind power}}
 
=== Mechanical power ===
[[File:Fourteenth century windmill.png|thumb|left|Medieval depiction of a [[wind mill]]]]
 
[[Sailboats]] and [[sailing ship]]s have been using wind power for thousands of years, and architects have used wind-driven [[natural ventilation]] in buildings since similarly ancient times. The use of wind to provide mechanical power came somewhat later in antiquity. The windwheel of the Greek engineer [[Heron of Alexandria]] in the 1st century AD is the earliest known instance of using a wind-driven wheel to power a machine.<ref name="Meri2005"/><ref name=Lohrmann/><ref name="Drachmann">Drachmann, A.G. (1961) "Heron's Windmill", ''Centaurus'', 7, pp. 145–151</ref>
 
The first windmills were in use in Persia at least by the 9th century and possibly as early as the 7th century.<ref name="Lucas2006a">[[Ahmad Y Hassan|Hassan, Ahmad Y]] and [[Donald Routledge Hill|Hill, Donald Routledge]] (1986). ''Islamic Technology: An illustrated history'', p. 54. [[Cambridge University Press]]. ISBN 0-521-42239-6.</ref>
The use of windmills became widespread across the Middle East and Central Asia, and later spread to China and India.<ref name="Meri2005">{{cite journal|doi=10.1038/scientificamerican0591-100|author=[[Donald Routledge Hill|Hill, Donald R.]]|title=Mechanical Engineering in the Medieval Near East|journal=Scientific American|date=May 1991|pages=64–69|volume=264|issue=5}} (cf. Hill, Donald R., [http://home.swipnet.se/islam/articles/HistoryofSciences.htm Mechanical Engineering])</ref> By 1000 AD, windmills were used to pump seawater for salt-making in China and  Sicily.<ref name=Kurlansky2002>Kurlansky, Mark (2002) ''Salt: a world history'',Penguin Books, London, ISBN 0-14-200161-9, p. 419</ref> Windmills were used extensively in Northwestern Europe to grind flour from the 1180s,<ref name=Lohrmann>{{cite journal|author=Lohrmann, Dietrich |title=Von der östlichen zur westlichen Windmühle|journal=Archiv für Kulturgeschichte|volume=77|issue =1|year=1995|pages=1–30 (10ff.)}}</ref> and [[windpumps]] were used to drain land for agriculture and for building.<ref name="Brief History">{{cite web|url=http://www.windmillersgazette.com/history.html|title=Brief History of Windmills in the New World|publisher=Windmillers' Gazette|author=Baker, T. Lindsay|accessdate=31 October 2012}}</ref> Early immigrants to the [[New World]] brought the technology with them from Europe.<ref name="Brief History" />
 
In the US, the development of the water-pumping windmill was the major factor in allowing the farming and ranching of vast areas otherwise devoid of readily accessible water.<ref name="mysanantantonio" /> Windpumps contributed to the expansion of rail transport systems throughout the world, by pumping water from water wells for [[steam locomotive]]s. The multi-bladed wind turbine atop a lattice tower made of wood or steel was a century a fixture of the landscape throughout rural America.<ref>{{cite web|url=http://www.greenenergyohio.org/page.cfm?pageID=339 |title=Windmills in Rural America |publisher=Greenenergyohio.org}}</ref>
 
In 1881, [[William Thomson, 1st Baron Kelvin|Lord Kelvin]] proposed using wind power when coal ran out, as "so little of it is left".<ref name=timeline>{{cite web|url=http://danielyergin.com/World-Energy-timeline/ |title=World Energy Timeline |publisher=Danielyergin.com |date=21 September 2011 |accessdate=11 January 2013}}</ref> Solar power was also proposed, at about the same time.<ref>{{cite web|url=http://www.environmentalhistory.org/brilliant/2012/10/29/intro/ |title=A surprising history |publisher=Environmentalhistory.org |date=29 October 2012 |accessdate=11 January 2013}}</ref>
 
=== Electrical power ===
[[File:Top 5 Wind Electricity Countries.png|thumb|left|Trends in the top five countries generating electricity from wind, 1980-2012 (US EIA)]]
[[File:James Blyth's 1891 windmill.jpg|thumb|left|Blyth's "windmill" at his cottage in Marykirk in 1891]]
 
In July 1887, a Scottish academic, Professor [[James Blyth (engineer)|James Blyth]], built a cloth-sailed wind turbine in the garden of his holiday cottage in Marykirk and used the electricity it produced to charge [[Accumulator (energy)|accumulators]] which he used to power the lights in his cottage.<ref name="Courier">{{cite web
 
| url = http://www.thecourier.co.uk/Community/Heritage-and-History/article/2332/renewable-energy-and-role-of-marykirk-s-james-blyth.html|title=Renewable energy and role of Marykirk's James Blyth
| last = Hardy | first = Chris
| archiveurl = http://web.archive.org/web/20120314025335/http://www.thecourier.co.uk/Community/Heritage-and-History/article/2332/renewable-energy-and-role-of-marykirk-s-james-blyth.html
| archivedate = 14 March 2012
| date = 6 July 2010
| work = The Courier
| publisher = D. C. Thomson & Co. Ltd.
| accessdate = 12 December 2010
 
}}</ref> His experiments culminated in a UK patent in 1891.<ref name="Price" /> In the winter of 1887–1888 US inventor [[Charles F. Brush]] produced electricity using a wind powered generator which powered his home and laboratory until about 1900. In the 1890s, the Danish scientist and inventor [[Poul la Cour]] constructed wind turbines to generate electricity, which was used to produce [[hydrogen]] and [[Oxygen]] by [[electrolysis]] and a mixture of the two gases was stored for use as a fuel.<ref name="Price" /> La Cour was the first to discover that fast rotating wind turbines with fewer rotor blades were the most efficient in generating electricity and in 1904 he founded the Society of Wind Electricians.<ref name="Nixon">{{cite web
 
| url = http://www.guardian.co.uk/environment/2008/oct/17/wind-power-renewable-energy
| title = Timeline: The history of wind power
| last = NIxon|first=Niki
| date =17 October 2008
| work = The Guardian
| publisher = Guardian News and Media Limited}}</ref>
 
[[File:Electric Power Generating Windmill system advertisement 1897.jpg|thumb|right|Advertisement for a wind-powered electric system, 1897]]
 
By the mid-1920s, 1 to 3-kilowatt wind generators developed by companies such as [[Parris-Dunn]] and [[Jacobs Wind]]-electric<ref name=timeline /> found widespread use in the rural areas of the mid-western [[Great Plains]] of the US but by the 1940s the demand for more power and the coming of the electrical grid throughout those areas made these small generators obsolete.<ref name="Dodge">{{cite web
| url = http://telosnet.com/wind/20th.html
| title = Part 2&nbsp;– 20th Century Developments|last=Dodge|first=Darrell M.
| work = Illustrated history of wind power development
| publisher = TelosNet Web Development}}</ref>
 
IN 1931 the French aeronautical engineer, [[Georges Jean Marie Darrieus|George Darrieus]] was granted a patent for the [[Darrieus wind turbine]] which uses vertical-axis [[airfoil]]s to create rotation<ref name="NTNU">{{cite web
 
| url = http://web.archive.org/web/20120328113737/http://www.ivt.ntnu.no/offshore2/?page_id=266
| title = The historical development of the wind turbine
| work= NTNU environmental studies: Wind power
| publisher =ivt.ntnu.no
 
}}</ref> and a 100&nbsp;kW precursor to the modern horizontal wind generator was used in Yalta, in the USSR. In 1956 [[Johannes Juul]], a former student of la Cour, built a 200&nbsp;kW, three-bladed [[Gedser wind turbine|turbine at Gedser]] in Denmark, which influenced the design of many later turbines.<ref name="Nixon" />
 
In 1975 the [[United States Department of Energy]] funded a project to develop utility-scale wind turbines. The [[NASA wind turbines]] project built thirteen experimental turbines which paved the way for much of the technology used today.<ref name="Nixon" /> Since then, turbines have increased greatly in size with the [[Enercon E-126]] capable of delivering up to 7.5 [[Megawatt]]s (MW).<ref group="nb">Wind turbine power output is measured in [[Watt|kilowatts]] (kW) or megawatts (MW), and energy output in [[Kilowatt hour|megawatt-hours]] (MWh), gigawatt-hours (GWh) or terawatt-hours or (TWh). One gigawatt-hour is one million kilowatt-hours, and one terawatt-hour is a billion kilowatt hours.</ref><ref>{{cite web
 
| url = http://www.windpowermonthly.com/news/1143257/Enercon-E-126-75MW-worlds-biggest/
| title = Enercon E-126 7.5MW still world's biggest
| publisher = Windpowermonthly.com
| date = 1 August 2012
| accessdate = 11 January 2013}}</ref> Wind turbine production has expanded to many countries and wind power is expected to grow worldwide in the twenty-first century.
 
== Wind energy ==
Wind energy is the [[kinetic energy]] of air in motion, also called [[wind]].
Total wind energy flowing through an imaginary area ''A'' during the time ''t'' is:
 
:<math>E = \frac{1}{2}mv^2 = \frac{1}{2}(Avt\rho)v^2 = \frac{1}{2}At\rho v^3,</math><ref name=physics>{{cite web|url=https://dspace.lasrworks.org/bitstream/handle/10349/145/fulltext.pdf |title=Harvesting the Wind: The Physics of Wind Turbines |format=PDF |accessdate=11 January 2013}}</ref>
 
where ''ρ'' is the [[density of air]]; ''v'' is the wind [[speed]]; ''Avt'' is the volume of air passing through ''A'' (which is considered perpendicular to the direction of the wind); ''Avtρ'' is therefore the mass ''m'' passing per unit time. Note that ½ ''ρv''<sup>2</sup> is the kinetic energy of the moving air per unit volume.
 
Power is energy per unit time, so the wind power incident on ''A'' (e.g. equal to the rotor area of a wind turbine) is:
 
:<math>P = \frac{E}{t} = \frac{1}{2}A\rho v^3.</math><ref name=physics />
 
Wind power in an open air stream is thus ''proportional'' to the ''third power'' of the wind speed; the available power increases eightfold when the wind speed doubles. Wind turbines for grid electricity therefore need to be especially efficient at greater wind speeds.
 
[[File:United States Wind Resources and Transmission Lines map.jpg|thumb|right|Map of available wind power for the [[Wind power in the United States|United States]]. Color codes indicate wind power density class. (click to see larger)]]
 
Wind is the movement of air across the surface of the Earth, affected by areas of high pressure and of low pressure.<ref name="what is wind?">{{cite web|url=http://web.archive.org/web/20110304181329/http://www.bwea.com/edu/wind.html|title=What is wind?|year=2010|work=Renewable UK: Education and careers|publisher=Renewable UK|accessdate=9 April 2012}}</ref> The surface of the Earth is heated unevenly by the Sun, depending on factors such as the angle of incidence of the sun's rays at the surface (which differs with latitude and time of day) and whether the land is open or covered with vegetation. Also, large bodies of water, such as the oceans, heat up and cool down slower than the land. The heat energy absorbed at the Earth's surface is transferred to the air directly above it and, as warmer air is less dense than cooler air, it rises above the cool air to form areas of high pressure and thus pressure differentials. The rotation of the Earth drags the atmosphere around with it causing turbulence. These effects combine to cause a constantly varying pattern of winds across the surface of the Earth.<ref name="what is wind?" />
 
The total amount of economically extractable power available from the wind is considerably more than present human power use from all sources.<ref>{{cite web|url=http://www.claverton-energy.com/how-much-wind-energy-is-there-brian-hurley-wind-site-evaluation-ltd.html|title=How Much Wind Energy is there?&nbsp;– Brian Hurley&nbsp;– Wind Site Evaluation Ltd|last=Hurley|first=Brian|publisher=Claverton Group|accessdate=8 April 2012}}</ref> Axel Kleidon of the Max Planck Institute in Germany, carried out a "top down" calculation on how much wind energy there is, starting with the incoming solar radiation that drives the winds by creating temperature differences in the atmosphere. He concluded that somewhere between 18 TW and 68 TW could be extracted.<ref name=nsc2012 /> Cristina Archer and [[Mark Z. Jacobson]] presented a "bottom-up" estimate, which unlike Kleidon's are based on actual measurements of wind speeds, and found that there is 1700 TW of wind power at an altitude of 100 metres over land and sea. Of this, "between 72 and 170 TW could be extracted in a practical and cost-competitive manner".<ref name=nsc2012>{{cite web |url=http://www.newscientist.com/article/mg21328491.700-power-paradox-clean-might-not-be-green-forever.html?full=true&print=true |title=Power paradox: Clean might not be green forever |author=Ananthaswamy, Anil and Le Page, Michael |date=30 January 2012 |work=New Scientist }}</ref> They later estimated 80 TW.<ref name=Jacobson2012>{{cite doi|10.1073/pnas.1208993109}}</ref> However research at [[Harvard University]] estimates 1 Watt/m<sup>2</sup> on average and 2–10 MW/km<sup>2</sup> capacity for large scale wind farms, suggesting that these estimates of total global wind resources are too high by a factor of about 4.<ref>{{cite doi|10.1088/1748-9326/8/1/015021}}</ref>
 
=== Distribution of wind speed ===
[[File:Lee Ranch Wind Speed Frequency.svg|thumb|right|Distribution of wind speed (red) and energy (blue) for all of 2002 at the Lee Ranch facility in Colorado. The histogram shows measured data, while the curve is the Rayleigh model distribution for the same average wind speed.]]
 
The strength of wind varies, and an average value for a given location does not alone indicate the amount of energy a wind turbine could produce there. To assess the frequency of wind speeds at a particular location, a probability distribution function is often fit to the observed data. Different locations will have different wind speed distributions. The [[Weibull distribution|Weibull]] model closely mirrors the actual distribution of hourly/ten-minute wind speeds at many locations. The Weibull factor is often close to 2 and therefore a [[Rayleigh distribution]] can be used as a less accurate, but simpler model.<ref>{{cite web|url=http://www.wind-power-program.com/wind_statistics.htm |title=Wind statistics and the Weibull distribution |publisher=Wind-power-program.com |accessdate=11 January 2013}}</ref>
 
=== High altitude winds ===
Power generation from winds usually comes from winds very close to the surface of the earth. Winds at higher altitudes are stronger and more consistent, and may have a global capacity of 380 TW.<ref name=Jacobson2012 /> Recent years have seen significant advances in technologies meant to [[High-altitude wind power|generate electricity from high altitude winds]].<ref>{{cite web|author=Levitan, Dave |url=http://e360.yale.edu/feature/high_altitude_wind_energy_huge_potential_and_hurdles/2576/ |title=High-Altitude Wind Energy: Huge Potential&nbsp;— And Hurdles |publisher=E360.yale.edu |date=24 September 2012}}</ref>
 
== Wind farms ==
{{Main|Wind farm}}
[[File:Jepirachí.jpg|thumb|right|Wind turbines at the Jepirachí Eolian Park in [[La Guajira]], [[Colombia]].]]
 
A wind farm is a group of [[wind turbine]]s in the same location used for production of electricity. A large wind farm may consist of several hundred individual wind turbines distributed over an extended area, but the land between the turbines may be used for agricultural or other purposes. A wind farm may also be located offshore.
 
Almost all large wind turbines have the same design&nbsp;— a horizontal axis wind turbine having an upwind rotor with three blades, attached to a nacelle on top of a tall tubular tower.  In a [[wind farm]], individual turbines are interconnected with a medium voltage (often 34.5 kV), power collection system and communications network. At a substation, this medium-voltage electric current is increased in voltage with a [[transformer]] for connection to the high voltage [[electric power transmission]] system.
 
Many of the largest operational onshore wind farms are located in the US. As of 2012, the [[Alta Wind Energy Center]] is the largest onshore wind farm in the world at 1020 MW, followed by the [[Shepherds Flat Wind Farm]] (845 MW), and the [[Roscoe Wind Farm]] (781.5 MW). As of September 2012, the [[Sheringham Shoal Offshore Wind Farm]] and the [[Thanet Wind Farm]] in the UK are the largest offshore wind farms in the world at 317 MW and 300 MW, followed by [[Horns Rev]] II (209 MW) in Denmark.
 
There are many large wind farms under construction including; [[London Array|The London Array (offshore)]] (630 MW), [[BARD Offshore 1]] (400 MW), [[Sheringham Shoal Offshore Wind Farm]] (317 MW), [[Lincs Wind Farm]] (offshore), [[Clyde Wind Farm]] (548 MW), [[Greater Gabbard wind farm]] (500 MW), [[Macarthur Wind Farm]] (420 MW), [[Lower Snake River Wind Project]] (343 MW) and [[Walney Wind Farm]] (367 MW).
 
{{wide image|Whitelee panorama.JPG|650px|A panoramic view of the [[Whitelee Wind Farm]] with Lochgoin Reservoir in the foreground.}}
 
=== Feeding into grid ===
[[Induction generator]]s, often used for wind power, require [[reactive power]] for [[Excitation (magnetic)|excitation]] so [[Electrical substation|substations]] used in wind-power collection systems include substantial [[capacitor]] banks for [[power factor correction]].<ref>[http://www.uwig.org/wind_turbine_tech_charac_draft_final.pdf Wind Generation Technical Characteristics] p.17</ref> Different types of wind turbine generators behave differently during transmission grid disturbances, so [[Wind energy software|extensive modelling]] of the dynamic electromechanical characteristics of a new wind farm is required by transmission system operators to ensure predictable stable behaviour during system faults (see: [[Low voltage ride through]]). In particular, induction generators cannot support the system voltage during faults, unlike steam or hydro turbine-driven synchronous generators. [[Doubly fed electric machine|Doubly fed machines]] generally have more desirable properties for grid interconnection.<ref>{{cite book|title=The Greening of IT: How Companies Can Make a Difference for the Environment|last=Lamb|first=John|year=2009|page=261|isbn=978-0-13-715083-0}}</ref><ref>{{cite book|title=Alternative Energy Technologies|last=Castellano|first=Robert|year=2012|page=26|isbn=978-2813000767}}</ref> Transmission systems operators will supply a wind farm developer with a ''grid code'' to specify the requirements for interconnection to the transmission grid. This will include [[power factor]], constancy of [[Utility frequency|frequency]] and dynamic behavior of the wind farm turbines during a system fault.<ref name="Demeo2005" /><ref name="Zavadil2005" />
 
=== Offshore wind power ===
{{Main|Offshore wind power|List of offshore wind farms}}
 
 
Offshore wind power refers to the construction of wind farms in large bodies of water to generate electricity. These installations can utilise the more frequent and powerful winds that are available in these locations and have less aesthetic impact on the landscape than land based projects. However, the construction and the maintenance costs are considerably higher.<ref name="Hulazan">{{cite web|url=http://www.renewables-info.com/drawbacks_and_benefits/offshore_wind_power_%E2%80%93_advantages_and_disadvantages.html|title=Offshore wind power&nbsp;– Advantages and disadvantages |last=Hulazan|first=Ned|date=16 February 2011|publisher=Renewable Energy Articles|accessdate=9 April 2012}}</ref><ref name="Millborrow">{{cite web|url=http://www.windpowermonthly.com/go/europe/news/1021043/Cutting-cost-offshore-wind-energy/|title=Cutting the cost of offshore wind energy|last=Millborrow|first=David|date=6 August 2010|work=Wind Power Monthly|publisher=Haymarket}}</ref> As of 2011, offshore wind farms were at least 3 times more expensive than onshore wind farms of the same nominal power<ref name="Jamieson" /> but these costs are expected to fall as the industry matures.<ref name="Bloomberg">{{cite web|url=http://www.bloomberg.com/news/2012-04-09/wind-power-seen-surging-as-custom-barges-cut-set-up-costs.html|title=Wind Power Seen Surging as Custom Barges Cut Set-up Costs|last= Morales |first=Alex|last2=Bakewell|first2=Sally|date=10 April 2012|work=Blloomberg News|publisher=Bloomberg L.P. }}</ref>
 
[[Siemens]] and [[Vestas]] are the leading turbine suppliers for offshore wind power. [[DONG Energy]], [[Vattenfall]] and [[E.ON]] are the leading offshore operators.<ref name=btm2010o /> As of October 2010, 3.16 GW of offshore wind power capacity was operational, mainly in Northern Europe. According to [[BTM Consult]], more than 16 GW of additional capacity will be installed before the end of 2014 and the UK and Germany will become the two leading markets. Offshore wind power capacity is expected to reach a total of 75 GW worldwide by 2020, with significant contributions from China and the US.<ref name="btm2010o" />
 
== Wind power capacity and production ==
{{Main|Wind power by country}}
[[File:Wind generation-with semilog plot.png|thumb|right|Worldwide wind generation up to 2010]]
 
Worldwide there are now over two hundred thousand wind turbines operating, with a total [[nameplate capacity]] of 282,482&nbsp;MW as of end 2012.<ref name="gws-2012" />  The [[European Union]] alone passed some 100,000 MW nameplate capacity in September 2012,<ref>{{cite web|url=http://www.upi.com/Business_News/Energy-Resources/2012/10/01/EU-wind-power-capacity-reaches-100GW/UPI-52431349087400/|title=EU wind power capacity reaches 100GW|date=1 October 2012|publisher=UPI|accessdate=31 October 2012}}</ref> while the United States surpassed 50,000 MW in August 2012 and [[Wind power in the People's Republic of China|China]]'s grid connected capacity passed 50,000 MW the same month.<ref>{{cite web|url=http://www.chinadaily.com.cn/bizchina/2012-08/16/content_15680451.htm|title=China's on-grid wind power capacity grows|publisher=China Daily|date=16 August 2012|accessdate=31 October 2012}}</ref><ref>{{cite web|url=http://cleantechnica.com/2012/08/10/us-reaches-50-gw-of-wind-energy-capacity-in-q2-of-2012/|title=US Reaches 50 GW of Wind Energy Capacity in Q2 of 2012|publisher=Clean Technica|date=10 August 2012|accessdate=31 October 2012}}</ref>
 
World wind generation capacity more than quadrupled between 2000 and 2006, doubling about every three years. [[Wind power in the United States|The United States pioneered wind farms]] and led the world in installed capacity in the 1980s and into the 1990s. In 1997 German installed capacity surpassed the U.S. and led until once again overtaken by the U.S. in 2008. China has been rapidly expanding its wind installations in the late 2000s and passed the U.S. in 2010 to become the world leader.
 
At the end of 2012, worldwide [[nameplate capacity]] of wind-powered generators was 282 [[gigawatt]]s (GW), growing by 44 GW over the preceding year.<ref name="gws-2012" /> According to the [[World Wind Energy Association]], an industry organization, in 2010 wind power generated 430 TWh or about 2.5% of worldwide electricity usage,<ref name="wwea" /> up from 1.5% in 2008 and 0.1% in 1997.<ref name="wor" /> Between 2005 and 2010 the average annual growth in new installations was 27.6%.<ref name=re /> Wind power market penetration is expected to reach 3.35% by 2013 and 8% by 2018.<ref name=re /><ref name=bt />
 
Several countries have already achieved relatively high levels of penetration, such as 28% of stationary (grid) electricity production in [[Wind power in Denmark|Denmark]] (2011),<ref name="Elstat">{{cite web|url=http://www.ens.dk/sites/ens.dk/files/info/tal-kort/statistik-noegletal/maanedsstatistik/el-maanedsstatistik.xls|title=Månedlig elforsyningsstatistik|location=summary tab B58-B72|publisher=''[[Danish Energy Agency]]''|date=18 January 2012|accessdate=11 March 2012}} {{da icon}}</ref> 19% in [[Wind power in Portugal|Portugal]] (2011),<ref name="renPT2011">{{cite web|url=http://www.centrodeinformacao.ren.pt/EN/InformacaoExploracao/Pages/EstatisticaMensal.aspx|title=Monthly Statistics&nbsp;– SEN|date=Feb 2012}}</ref> 16% in [[Wind power in Spain|Spain]] (2011),<ref name="ree2011prelim">{{cite web|url=http://www.ree.es/ingles/sistema_electrico/pdf/infosis/Avance_REE_2011_ingles.pdf | title= the Spanish electricity system: preliminary report 2011| date=Jan 2012|page=13}}</ref> 16% in [[Wind power in Ireland|Ireland]] (2012)<ref name="eirgrid renewables" /> and 8% in [[Wind power in Germany|Germany]] (2011).<ref>{{cite web|url=http://www.bmwi.de/Dateien/BMWi/PDF/energiewende-in-deutschland,property=pdf,bereich=bmwi,sprache=de,rwb=true.pdf | title=Die Energiewende in Deutschland | date=February 2012 | author=[[Federal Ministry of Economics and Technology (Germany)|Bundesministerium für Wirtschaft und Technologie]]|location=Berlin|page=4}} {{de icon}}</ref> As of 2011, 83 countries around the world were using wind power on a commercial basis.<ref name=ren212011 />
 
[[wind power in Europe|Europe]] accounted for 48% of the world total wind power generation capacity in 2009. In 2010, Spain became Europe's leading producer of wind energy, achieving 42,976 GWh. Germany held the top spot in Europe in terms of installed capacity, with a total of 27,215 MW as of 31 December 2010.<ref name="eolicenergynews4082" />
 
<center>
{| class="wikitable
|
{| class="wikitable sortable"
|+Top 10 countries<br />by nameplate windpower capacity<br />(2012 year-end)<ref name=gws-2012>{{cite web| title= Global Wind Report Annual market update 2012
| url=http://www.gwec.net/wp-content/uploads/2012/06/Annual_report_2012_LowRes.pdf |format=PDF | publisher=Global Wind Energy Council | accessdate=23 April 2013}}</ref>
|-
! Country !! New 2012<br />capacity ([[Megawatt|MW]]) !! Windpower total capacity<br />([[Megawatt|MW]])  <!--
 
[the following note indicator is temporarily removed until needed for preliminary date in 2014:] <small><sup>ǂ</sup>provisional</small>
--> !! % world total
|-
| [[Wind power in China|China]] ||align=center| 12,960 ||align=center| 75,324  ||align=center| 26.7
|-
| [[Wind power in the United States|United States]] ||align=center| 13,124 ||align=center| 60,007 ||align=center| 21.2
|-
| [[Wind power in Germany|Germany]] ||align=center| 2,145 ||align=center| 31,308 ||align=center| 11.1
|-
| [[Wind power in Spain|Spain]] ||align=center| 1,122 ||align=center| 22,796 ||align=center| 8.1
|-
| [[Wind power in India|India]] ||align=center| 2,336 ||align=center| 18,421 ||align=center| 6.5
|-
| [[Wind energy in the United Kingdom|UK]] ||align=center| 1,897 ||align=center| 8,845 ||align=center| 3.0
|-
| [[Wind power in Italy|Italy]] ||align=center| 1,273 ||align=center| 8,144 ||align=center| 2.9
|-
| [[Wind power in France|France]] ||align=center| 757 ||align=center| 7,564  ||align=center| 2.7
|-
| [[Wind power in Canada|Canada]] ||align=center| 935 ||align=center| 6,200 ||align=center| 2.2
|-
| [[Wind power in Portugal|Portugal]] ||align=center| 145 ||align=center| 4,525 ||align=center| 1.6
|-
| ([[:Category:Wind power by country|rest of world]]) ||align=center| 6,737 ||align=center| 39,853 ||align=center| 14.1
|-
|align=center| '''World total''' ||align=center| '''44,799 MW''' ||align=center|  '''282,587 MW''' ||align=center| '''100%'''
|}
||
{| class="wikitable"
|+Top 10 countries<br />by windpower electricity production<br />(2011 totals)<ref>{{cite web|publisher=Observ'ER|url=http://www.energies-renouvelables.org/observ-er/html/inventaire/pdf/14e-inventaire-Chap02.pdf|location=2.2 Electricity Production From Wind Sources: Main Wind Power Producing Countries&nbsp;– 2011 (text & table)|title=Worldwide Electricity Production From Renewable Energy Sources: Stats and Figures Series: Fourteenth Inventory&nbsp;– Edition 2012|accessdate=15 January 2013}}</ref>
|-
! Country !! Windpower production<br />([[Kilowatt hour#Watt hour multiples and billing units|TWh]]) !! % world total
|-
| United States ||align=center| 120.5 ||align=center| 26.2
|-
| China ||align=center| 88.6 ||align=center| 19.3
|-
| Germany ||align=center| 48.9 ||align=center| 10.6
|-
| Spain ||align=center| 42.4 ||align=center| 9.2
|-
| India ||align=center| 24.9 ||align=center| 5.4
|-
| Canada ||align=center| 19.7 ||align=center| 4.3
|-
| UK ||align=center| 15.5 ||align=center| 3.4
|-
| France ||align=center| 12.2 ||align=center| 2.7
|-
| Italy ||align=center| 9.9 ||align=center| 2.1
|-
| Denmark ||align=center| 9.8 ||align=center| 2.1
|-
| (rest of world) ||align=center| 67.7 ||align=center| 14.7
|-
|align=center| '''World total''' ||align=center|  '''459.9 TWh''' ||align=center| '''100%'''
|}
|}
</center>
 
=== Growth trends ===
[[File:Total Installed Wind Capacity 1997-2020-MW.jpg|thumb|Worldwide installed capacity 1997–2020 [MW], developments and prognosis. Data source: WWEA<ref>{{cite web|url=http://www.wwindea.org/home/images/stories/worldwindenergyreport2009_s.pdf|title=World Wind Energy Association|accessdate=31 October 2012}}</ref>]]
[[File:GlobalWindPowerCumulativeCapacity-withForcast.png|thumb|right|Worldwide installed wind power capacity forecast (Source: [[Global Wind Energy Council]])<ref name="GWEC_Market" /><ref name="GWEC_Forcast" />]]
 
In 2010, more than half of all new wind power was added outside of the traditional markets in Europe and North America. This was largely from new construction in China, which accounted for nearly half the new wind installations (16.5 GW).<ref name="increasesBy2010" />
 
Global Wind Energy Council (GWEC) figures show that 2007 recorded an increase of installed capacity of 20&nbsp;GW, taking the total installed wind energy capacity to 94&nbsp;GW, up from 74&nbsp;GW in 2006. Despite constraints facing supply chains for wind turbines, the annual market for wind continued to increase at an estimated rate of 37%, following 32% growth in 2006. In terms of economic value, the wind energy sector has become one of the important players in the energy markets, with the total value of new generating equipment installed in 2007 reaching €25 billion, or US$36 billion.<ref name="gwec2007" />
 
Although the [[wind power industry]] was affected by the [[Late-2000s recession|global financial crisis]] in 2009 and 2010, a [[BTM Consult]] five-year forecast up to 2013 projects substantial growth. Over the past five years the average growth in new installations has been 27.6% each year. In the forecast to 2013 the expected average annual growth rate is 15.7%.<ref name="re" /><ref name="bt" /> More than 200&nbsp;GW of new wind power capacity could come on line before the end of 2013. Wind power market penetration is expected to reach 3.35% by 2013 and 8% by 2018.<ref name=re /><ref name=bt />
 
=== Capacity factor ===
[[File:GlobalWindPowerCumulativeCapacity.png|thumb|Worldwide installed wind power capacity (Source: [[Global Wind Energy Council|GWEC]])<ref name=gws-2011>{{cite web|title=GWEC Global Wind Statistics 2011|url=http://gwec.net/wp-content/uploads/2012/06/GWEC_-_Global_Wind_Statistics_2011.pdf|format=PDF|publisher=Global Wind Energy Commission|accessdate=15 March 2012}}</ref>]]
 
Since wind speed is not constant, a wind farm's annual [[energy]] production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the [[capacity factor]]. Typical capacity factors are 15–50%; values at the upper end of the range are achieved in favourable sites and are due to wind turbine design improvements.<ref name="ceereCapInter" /><ref name=capacity-factor-50>{{cite web|last=Shahan |first=Zachary |url=http://cleantechnica.com/2012/07/27/wind-turbine-net-capacity-factor-50-the-new-normal/ |title=Wind Turbine Net Capacity Factor&nbsp;– 50% the New Normal? |publisher=Cleantechnica.com |date=27 July 2012 |accessdate=11 January 2013}}</ref><ref group="nb">For example, a 1&nbsp;MW turbine with a capacity factor of 35% will not produce 8,760&nbsp;MW·h in a year (1 × 24 × 365), but only 1 × 0.35 × 24 × 365&nbsp;=&nbsp;3,066&nbsp;MW·h, averaging to 0.35&nbsp;MW.</ref>
 
Online data is available for some locations, and the capacity factor can be calculated from the yearly output.<ref name="MassMaritime" /><ref name="iesoOntarioWind" /> For example, the German nation-wide average wind power capacity factor over all of 2012 was just under 17.5% (45867&nbsp;GW·h/yr&nbsp;/&nbsp;(29.9&nbsp;GW&nbsp;×&nbsp;24&nbsp;×&nbsp;366)&nbsp;=&nbsp;0.1746),<ref>{{cite web| url=http://www.ise.fraunhofer.de/en/downloads-englisch/pdf-files-englisch/news/electricity-production-from-solar-and-wind-in-germany-in-2012.pdf |title=Electricity production from solar and wind in Germany in 2012 |date=8 February 2013 |publisher=Fraunhofer Institute for Solar Energy Systems ISE |archiveurl=http://www.webcitation.org/6FPO6HLOq |archivedate=26 March 2013}}</ref>{{Failed verification|date=July 2013}} and the capacity factor for Scottish wind farms averaged 24% between 2008 and 2010.<ref name =WindPower>(6 April 2011) [http://www.jmt.org/news.asp?s=2&cat=Campaigning&nid=JMT-N10561 Report Questions Wind Power’s Ability to Deliver Electricity When Most Needed] John Muir Trust and Stuart Young Consulting, Retrieved 26 March 2013</ref>
 
Unlike fueled generating plants, the capacity factor is affected by several parameters, including the variability of the wind at the site and the size of the [[Electric generator|generator]] relative to the turbine's swept area. A small generator would be cheaper and achieve a higher capacity factor but would produce less [[Electric power|electricity]] (and thus less profit) in high winds. Conversely, a large generator would cost more but generate little extra power and, depending on the type, may [[Stall (flight)|stall]] out at low wind speed. Thus an optimum capacity factor of around 40–50% would be aimed for.<ref name=capacity-factor-50 /><ref name="capFactors" />
 
In a 2008 study released by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy, the capacity factor achieved by the U.S. wind turbine fleet is shown to be increasing as the technology improves. The capacity factor achieved by new wind turbines in 2010 reached almost 40%.<ref name="Windpowering" /><ref>{{cite web|url=http://en.openei.org/apps/TCDB/ |title=Transparent Cost Database |publisher=En.openei.org |date=20 March 2009 |accessdate=11 January 2013}}</ref>
 
=== Penetration ===
Wind energy penetration refers to the fraction of energy produced by wind compared with the total available generation capacity. There is no generally accepted maximum level of wind penetration. The limit for a particular [[Electrical grid|grid]] will depend on the existing generating plants, pricing mechanisms, capacity for [[energy storage]], demand management and other factors. An interconnected electricity grid will already include [[Operating reserve|reserve generating]] and [[Electric power transmission#Capacity|transmission capacity]] to allow for equipment failures. This reserve capacity can also serve to compensate for the varying power generation produced by wind plants. Studies have indicated that 20% of the total annual electrical energy consumption may be incorporated with minimal difficulty.<ref name="tacklingUS" /> These studies have been for locations with geographically dispersed wind farms, some degree of [[Dispatchable generation|dispatchable energy]] or [[hydropower]] with storage capacity, demand management, and interconnected to a large grid area enabling the export of electricity when needed. Beyond the 20% level, there are few technical limits, but the economic implications become more significant. Electrical utilities continue to study the effects of large scale penetration of wind generation on system stability and economics.<ref name="NGestimates" /><ref name="minnesota" /><ref name="ESB2004Study" /><ref name="sinclairMerz" />
 
A wind energy penetration figure can be specified for different durations of time. On an annual basis, as of 2011, few grid systems have penetration levels above 5%: Denmark&nbsp;– 29%, Portugal&nbsp;– 19%, Spain&nbsp;– 19%, Ireland&nbsp;– 18%, and Germany&nbsp;– 11%. For the U.S. in 2011, the penetration level was estimated at 3.3%.<ref name="wtmr_2010_eere">{{cite book|url=http://www1.eere.energy.gov/wind/pdfs/2011_wind_technologies_market_report.pdf|title=2011 Wind Technologies Market Report|publisher=EERE, U.S. Department of Energy|page=7}}</ref> To obtain 100% from wind annually requires substantial long term storage. On a monthly, weekly, daily, or hourly basis—or less—wind can supply as much as or more than 100% of current use, with the rest stored or exported. Seasonal industry can take advantage of high wind and low usage times such as at night when wind output can exceed normal demand. Such industry can include production of silicon, aluminum, steel, or of natural gas, and hydrogen, which allow long term storage, facilitating 100% energy from [[variable renewable energy]].<ref>{{cite web|author= Luoma, Jon R. |url=http://e360.yale.edu/feature/the_challenge_for_green_energy_how_to_store_excess_electricity/2170/ |title=The Challenge for Green Energy: How to Store Excess Electricity |publisher=E360.yale.edu |date= 13 July 2001}}</ref><ref>{{cite web|url=http://web.archive.org/web/20121005211707/http://revmodo.com/2012/08/23/power-to-gas-technology-turns-excess-wind-energy-into-natural-gas/ |author=Buczynski, Beth |title=Power To Gas Technology Turns Excess Wind Energy Into Natural Gas |publisher=Revmodo.com |date=23 August 2012}}</ref> Homes can also be programmed to accept extra electricity on demand, for example by remotely turning up water heater thermostats.<ref>Wals, Matthew L. (4 November 2011) [http://www.nytimes.com/2011/11/05/business/energy-environment/as-wind-energy-use-grows-utilities-seek-to-stabilize-power-grid.html?pagewanted=all&_r=0 Taming Unruly Wind Power]. New York Times.</ref>
 
=== Variability ===
{{Main|Intermittent energy source}}
[[File:Toro de osborne.jpg|thumb|left|Windmills are typically installed in favourable windy locations. In the image, wind power [[Wind power in Spain|generators in Spain]], near an [[Osborne bull]].]]
Electricity generated from wind power can be highly variable at several different timescales: hourly, daily, or seasonally. Annual variation also exists, but is not as significant.
 
Because instantaneous electrical generation and consumption must remain in balance to maintain grid stability, this variability can present substantial challenges to incorporating large amounts of wind power into a grid system. Intermittency and the non-[[Intermittent power sources#Terminology|dispatchable]] nature of wind energy production can raise costs for regulation, incremental [[operating reserve]], and (at high penetration levels) could require an increase in the already existing [[energy demand management]], [[load shedding]], storage solutions or system interconnection with [[High-voltage direct current|HVDC]] cables.
 
Fluctuations in load and allowance for failure of large fossil-fuel generating units require reserve capacity that can also compensate for variability of wind generation.
 
{| class="wikitable" style="float: right; margin: .56em 0 0 .8em;"
|+ Increase in system operation costs, Euros per MWh, for 10% & 20% wind share<ref name="ieawind" />
|-
! scope="col" | Country !! scope="col" | 10% !! scope="col" | 20%
|-
| Germany || 2.5 || 3.2
|-
| Denmark || 0.4 || 0.8
|-
| Finland || 0.3 || 1.5
|-
| Norway || 0.1 || 0.3
|-
| Sweden || 0.3 || 0.7
|}
 
Wind power is however, variable, but during low wind periods it can be replaced by other power sources. Transmission networks presently cope with outages of other generation plants and daily changes in electrical demand, but the variability of [[intermittent power source]]s such as wind power, are unlike those of conventional power generation plants which, when scheduled to be operating, may be able to deliver their nameplate capacity around 95% of the time.
 
Presently, grid systems with large wind penetration require a small increase in the frequency of usage of [[natural gas]] spinning reserve power plants to prevent a loss of electricity in the event that conditions are not favorable for power production from the wind. At lower wind power grid penetration, this is less of an issue.<ref name="is windpower reliable" /><ref name="clavertonReliable" /><ref>Milligan, Michael (October 2010) [http://www.nrel.gov/docs/fy11osti/49019.pdf Operating Reserves and Wind Power Integration: An International Comparison]. National Renewable Energy Laboratory, p. 11.</ref>
 
GE has installed a prototype wind turbine with onboard battery similar to that of an electric car, equivalent of 1 minute of production. Despite the small capacity, it is enough to guarantee that power output complies with forecast for 15 minutes, as the battery is used to eliminate the difference rather than provide full output. The increased predictability can be used to take wind power penetration from 20 to 30 or 40 per cent. The battery cost can be retrieved by selling burst power on demand and reducing backup needs from gas plants.<ref>Bullis, Kevin. "[http://www.technologyreview.com/news/514331/wind-turbines-battery-included-can-keep-power-supplies-stable/ Wind Turbines, Battery Included, Can Keep Power Supplies Stable]" [[Technology Review]], 7 May 2013. Accessed: 29 June 2013.</ref>
 
A report on Denmark's wind power noted that their wind power network provided less than 1% of average demand on 54 days during the year 2002.<ref name="Denmark" /> Wind power advocates argue that these periods of low wind can be dealt with by simply restarting existing power stations that have been held in readiness, or interlinking with HVDC.<ref name="Czisch-Giebel" /> Electrical grids with slow-responding thermal power plants and without ties to networks with hydroelectric generation may have to limit the use of wind power.<ref name="Denmark" /> According to a 2007 Stanford University study published in the Journal of Applied Meteorology and Climatology, interconnecting ten or more wind farms can allow an average of 33% of the total energy produced (i.e. about 8% of total nameplate capacity) to be used as reliable, [[baseload power|baseload electric power]] which can be relied on to handle peak loads, as long as minimum criteria are met for wind speed and turbine height.<ref name="connecting_wind_farms" /><ref name="Archer2007" />
 
Conversely, on particularly windy days, even with penetration levels of 16%, wind power generation can surpass all other electricity sources in a country. In Spain, on 16 April 2012 wind power production reached the highest percentage of electricity production till then, with wind farms covering 60.46% of the total demand.<ref name="eolica" />
 
A 2006 [[International Energy Agency]] forum presented costs for managing intermittency as a function of wind-energy's share of total capacity for several countries, as shown in the table on the right. Three reports on the wind variability in the UK issued in 2009, generally agree that variability of wind needs to be taken into account, but it does not make the grid unmanageable. The additional costs, which are modest, can be quantified.<ref name="abbess" />
 
[[Solar power]] tends to be complementary to wind.<ref name="windsun" /><ref name="smallWindSystems" /> On daily to weekly timescales, [[high pressure area]]s tend to bring clear skies and low surface winds, whereas [[low pressure area]]s tend to be windier and cloudier. On seasonal timescales, solar energy peaks in summer, whereas in many areas wind energy is lower in summer and higher in winter.<ref group="nb">[[Wind power in California|California]] and [[Wind power in Minnesota|Minnesota]] are exceptions.</ref><ref name="cleveland_water_crib" /> Thus the intermittencies of wind and solar power tend to cancel each other somewhat. In 2007 the Institute for Solar Energy Supply Technology of the [[University of Kassel]] pilot-tested a [[virtual power plant|combined power plant]] linking solar, wind, [[biogas]] and [[Pumped-storage hydroelectricity|hydrostorage]] to provide load-following power around the clock and throughout the year, entirely from renewable sources.<ref name="combined_power_plant" />
 
{{Further|Grid balancing}}
 
=== Predictability ===
{{Main|Wind power forecasting}}
Wind power forecasting methods are used, but predictability of any particular wind farm is low for short-term operation. For any particular generator there is an 80% chance that wind output will change less than 10% in an hour and a 40% chance that it will change 10% or more in 5 hours.<ref>{{cite web|url=http://www.nrel.gov/wind/systemsintegration/system_integration_basics.html|title=Wind Systems Integration Basics|archiveurl=http://web.archive.org/web/20120607000124/http://www.nrel.gov/wind/systemsintegration/system_integration_basics.html|archivedate=7 June 2012}}</ref>
 
However, studies by Graham Sinden (2009) suggest that, in practice, the variations in thousands of wind turbines, spread out over several different sites and wind regimes, are smoothed.  As the distance between sites increases, the correlation between wind speeds measured at those sites, decreases.<ref name = Diesendorf>{{cite journal| author = Diesendorf, Mark |year= 2007| title =[[Greenhouse Solutions with Sustainable Energy]]|page =119| quote =Graham Sinden analysed over 30 years of hourly wind speed data from 66 sites spread out over the United Kingdom.  He found that the correlation coefficient of wind power fell from 0.6 at 200&nbsp;km to 0.25 at 600&nbsp;km separation (a perfect correlation would have a coefficient equal to 1.0.) There were no hours in the data set where wind speed was below the cut-in wind speed of a modern wind turbine throughout the United Kingdom, and low wind speed events affecting more than 90 per cent of the United Kingdom had an average recurrent rate of only one hour per year.}}</ref>
 
Thus, while the output from a single turbine can vary greatly and rapidly as local wind speeds vary, as more turbines are connected over larger and larger areas the average power output becomes less variable and more predictable.<ref>{{cite web |url= http://www.uwig.org/IEA_Report_on_variability.pdf |title=Variability of Wind Power and other Renewables: Management Options and Strategies  |publisher=IEA |year=2005 |format=PDF }}</ref>
 
Wind speeds can be accurately forecast over large areas, and hence wind is a predictable source of power for feeding into an electrical grid. However, due to the variability, although predictable, wind energy availability must be scheduled.{{citation needed|date=January 2014}}
 
=== Reliability ===
Wind power hardly ever suffers major technical failures, since failures of individual wind turbines have hardly any effect on overall power, so that the distributed wind power is highly reliable and predictable,<ref>{{cite news|last=Peterson|first=Kristen|title=The reliability of wind power|url=http://www.mndaily.com/2012/11/05/reliability-wind-power|newspaper=Minnesota Daily|date=5 November 2012}}</ref> whereas conventional generators, while far less variable, can suffer major unpredictable outages.
 
=== Integration with other sources ===
The combination of diversifying variable renewables by type and location, forecasting their variation, and integrating them with dispatchable renewables, flexible fueled generators, and demand response can create a power system that has the potential to meet power supply needs reliably. Integrating ever-higher levels of renewables is being successfully demonstrated in the real world:<ref name=Lovins11>{{cite book|authorlink=Amory Lovins|year=2011|title=[[Reinventing Fire]]|publisher=Chelsea Green Publishing|page=199}}</ref>
<blockquote>
 
In 2009, eight American and three European authorities, writing in the leading electrical engineers' professional journal, didn't find "a credible and firm technical limit to the amount of wind energy that can be accommodated by electricity grids". In fact, not one of more than 200 international studies, nor official studies for the eastern and western U.S. regions, nor the [[International Energy Agency]], has found major costs or technical barriers to reliably integrating up to 30% variable renewable supplies into the grid, and in some studies much more.&nbsp;– ''Reinventing Fire''<ref name=Lovins11 />
</blockquote>
 
=== Energy storage ===
In general, hydroelectricity complements wind power very well. When the wind is blowing strongly, nearby hydroelectric plants can temporarily hold back their water, and when the wind drops they can rapidly increase production again giving a very even power supply.
 
[[Pumped-storage hydroelectricity]] or other forms of [[grid energy storage]] can store energy developed by high-wind periods and release it when needed.<ref name="Mitchell 2006" /> The type of storage needed depends on the wind penetration level&nbsp;– low penetration requires daily storage, and high penetration requires both short and long term storage&nbsp;– as long as a month or more. Stored energy increases the economic value of wind energy since it can be shifted to displace higher cost generation during peak demand periods. The potential revenue from this [[arbitrage]] can offset the cost and losses of storage; the cost of storage may add 25% to the cost of any wind energy stored but it is not envisaged that this would apply to a large proportion of wind energy generated. For example, in the UK, the 1.7 GW [[Dinorwig pumped storage plant]] evens out electrical demand peaks, and allows base-load suppliers to run their plants more efficiently. Although pumped storage power systems are only about 75% efficient, and have high installation costs, their low running costs and ability to reduce the required electrical base-load can save both fuel and total electrical generation costs.<ref name="dinorwig" /><ref name="futureStorage" />
 
In particular geographic regions, peak wind speeds may not coincide with peak demand for electrical power. In the US states of California and [[Wind power in Texas|Texas]], for example, hot days in summer may have low wind speed and high electrical demand due to the use of [[air conditioning]]. Some utilities subsidize the purchase of [[geothermal heat pump]]s by their customers, to reduce electricity demand during the summer months by making air conditioning up to 70% more efficient;<ref name="geothermal_incentive" /> widespread adoption of this technology would better match electricity demand to wind availability in areas with hot summers and low summer winds. Another option is to interconnect widely dispersed geographic areas with an HVDC "[[Super grid]]". In the U.S. it is estimated that to upgrade the transmission system to take in planned or potential renewables would cost at least $60 billion.<ref name="slogin" />
 
Germany has an installed capacity of wind and solar that exceeds daily demand, and has been exporting peak power to neighboring countries. A more practical solution is the installation of thirty days storage capacity able to supply 80% of demand, which will become necessary when most of Europe's energy is obtained from wind power and solar power. Just as the EU requires member countries to maintain 90 days [[Global strategic petroleum reserves|strategic reserves]] of oil it can be expected that countries will provide electricity storage, instead of expecting to use their neighbors for net metering.<ref>{{cite web|url=http://www.europarl.europa.eu/document/activities/cont/201202/20120208ATT37544/20120208ATT37544EN.pdf|title=European Renewable Energy Network|format=PDF|page=71|date=January 2012|author=Altmann, M. ''et al.''|publisher=European Parliament}}</ref>
 
=== Capacity credit and fuel savings ===
The capacity credit of wind is estimated by determining the capacity of conventional plants displaced by wind power, whilst maintaining the same degree of system security,.<ref name="The facts">{{cite web|url=http://www.wind-energy-the-facts.org/en/part-2-grid-integration/chapter-6-wind-power-contribution-to-system-adequacy/capacity-credit-of-wind-power/|title=Capacity Credit of Wind Power:  Capacity credit is the measure for firm wind power|work=Wind Energy the Facts|publisher=EWEA}}</ref> However, the precise value is irrelevant since the main value of wind is its fuel and {{CO2}} savings,{{citation needed|date=January 2014}} and wind is not expected to be constantly available.<ref>{{cite web|url=http://www.wind-energy-the-facts.org/en/part-2-grid-integration/chapter-6-wind-power-contribution-to-system-adequacy/capacity-credit-of-wind-power/capacity-credit-values-of-wind-power.html |title=Capacity Credit Values of Wind Power |publisher=Wind-energy-the-facts.org }}</ref>
 
== Economics ==
Wind turbines reached [[grid parity]] (the point at which the cost of wind power matches traditional sources) in some areas of Europe in the mid-2000s, and in the US around the same time. Falling prices continue to drive the levelized cost down and it has been suggested that it has reached general grid parity in Europe in 2010, and will reach the same point in the US around 2016 due to an expected reduction in capital costs of about 12%.<ref name="businessgreen">[http://www.businessgreen.com/bg/news/2124487/onshore-wind-reach-grid-parity-2016 "Onshore wind to reach grid parity by 2016"], BusinessGreen, 14 November 2011</ref> Nevertheless, a significant amount of the wind power resource in North America remains above grid parity due to the long transmission distances involved.
 
=== Cost trends ===
[[File:Danish wind power LCOE vs wind speed in 2012.png|thumb|Estimated cost per MWh for wind power in Denmark]]
[[File:US projected cost of wind power.png|thumb|The [[National Renewable Energy Laboratory]] projects that the levelized cost of wind power in the U.S. will decline about 25% from 2012 to 2030.<ref>Lantz, E.;  Hand, M. and Wiser, R. (13–17 May 2012) [http://www.nrel.gov/docs/fy12osti/54526.pdf "The Past and Future Cost of Wind Energy,"] National Renewable Energy Laboratory conference paper no. 6A20-54526, p. 4</ref>]]
[[File:Turbine Blade Convoy Passing through Edenfield.jpg|thumb|A turbine blade convoy passing through [[Edenfield]] in the U.K. (2008). Even longer [[Wind turbine design#Blade design|two-piece blades]] are now manufactured, and then assembled on-site to reduce difficulties in transportion.]]
 
Wind power is [[capital intensive]], but has no fuel costs.<ref>Dolf Gielen. "[http://www.irena.org/DocumentDownloads/Publications/RE_Technologies_Cost_Analysis-WIND_POWER.pdf RENEWABLE ENERGY TECHNOLOGIES: COST ANALYSIS SERIES : Wind Power]" ''[[International Renewable Energy Agency]]'', June 2012. Accessed: 19 October 2013. Quote: "wind is capital intensive, but has no fuel costs"</ref> The [[marginal cost]] of wind energy once a plant is constructed is usually less than 1-cent per kW·h.<ref name="Patel" /> This cost has reduced as wind turbine technology improved. There are now longer and lighter wind turbine blades, improvements in turbine performance and increased power generation efficiency. Also, wind project capital and maintenance costs have continued to decline.<ref>{{cite web
 
| url = http://www.whitehouse.gov/blog/2012/08/14/banner-year-us-wind-industry
| title = A Banner Year for the U.S. Wind Industry
| author = Danielson, David
| date = 14 August 2012
| work = Whitehouse Blog }}</ref>
 
The estimated [[average cost]] per unit incorporates the cost of construction of the turbine and transmission facilities, borrowed funds, return to investors (including cost of risk), estimated annual production, and other components, averaged over the projected useful life of the equipment, which may be in excess of twenty years. Energy cost estimates are highly dependent on these assumptions so published cost figures can differ substantially. In 2004, wind energy cost a fifth of what it did in the 1980s, and some expected that downward trend to continue as larger multi-megawatt [[Wind turbine|turbines]] were mass-produced.<ref name="helming" /> {{As of|2012}} capital costs for wind turbines are substantially lower than 2008–2010 but are still above 2002 levels.<ref>{{cite web
 
| title = LBNL/NREL Analysis Predicts Record Low LCOE for Wind Energy in 2012–2013
| work = US Department of Energy Wind Program Newsletter
| url = http://apps1.eere.energy.gov/wind/newsletter/detail.cfm/articleId=45
| accessdate =10 March 2012
 
}}</ref> A 2011 report from the American Wind Energy Association stated, "Wind's costs have dropped over the past two years, in the range of 5 to 6 cents per kilowatt-hour recently.... about 2 cents cheaper than coal-fired electricity, and more projects were financed through debt arrangements than tax equity structures last year.... winning more mainstream acceptance from Wall Street's banks.... Equipment makers can also deliver products in the same year that they are ordered instead of waiting up to three years as was the case in previous cycles.... 5,600 MW of new installed capacity is under construction in the United States, more than double the number at this point in 2010. Thirty-five percent of all new power generation built in the United States since 2005 has come from wind, more than new gas and coal plants combined, as power providers are increasingly enticed to wind as a convenient hedge against unpredictable commodity price moves."<ref name="salerno" />
 
A British Wind Energy Association report gives an average generation cost of onshore wind power of around 3.2 pence (between US 5 and 6 cents) per kW·h (2005).<ref name="BWEA" /> Cost per unit of energy produced was estimated in 2006 to be comparable to the cost of new generating capacity in the US for coal and natural gas: wind cost was estimated at $55.80 per MW·h, coal at $53.10/MW·h and natural gas at $52.50.<ref name="eiadoe" /> Similar comparative results with natural gas were obtained in a governmental study in the UK in 2011.<ref name="ccc" /> The presence of wind energy, even when subsidised, can reduce costs for consumers (€5 billion/yr in Germany) by reducing the marginal price, by minimising the use of expensive [[peaking power plant]]s.<ref name="meritorder" />
 
In February 2013 [[Bloomberg L.P.|Bloomberg]] New Energy Finance reported that the cost of generating electricity from new wind farms is cheaper than new coal or new baseload gas plants. When including the current [[Carbon pricing in Australia|Australian federal government carbon pricing]] scheme their modeling gives costs (in Australian dollars) of $80/MWh for new wind farms, $143/MWh for new coal plants and $116/MWh for new baseload gas plants. The modeling also shows that "even without a carbon price (the most efficient way to reduce economy-wide emissions) wind energy is 14% cheaper than new coal and 18% cheaper than new gas."<ref name="bnef.com/2013/02/07/renewable-cheaper">{{cite news
 
| title = Renewable energy now cheaper than new fossil fuels in Australia
| newspaper = Bloomberg New Energy Finance
| location = Sydney
| publisher = Bloomberg Finance
| date = 7 February 2013
| url = http://about.bnef.com/2013/02/07/renewable-energy-now-cheaper-than-new-fossil-fuels-in-australia/
 
}}</ref> Part of the higher costs for new coal plants is due to high financial lending costs because of "the reputational damage of emissions-intensive investments". The expense of gas fired plants is partly due to "export market" effects on local prices. Costs of production from coal fired plants built in "the 1970s and 1980s" are cheaper than renewable energy sources because of depreciation.<ref name="bnef.com/2013/02/07/renewable-cheaper" />
 
A 2009 study on wind power in Spain by Gabriel Calzada Alvarez of [[King Juan Carlos University]] concluded that each installed MW of wind power led to the loss of 4.27 jobs, by raising energy costs and driving away electricity-intensive businesses.<ref name="juande" /> However, the U.S. Department of Energy found the study to be seriously flawed, and the conclusion unsupported.<ref name="nrelemployment" />
 
Theoretical analysis suggests that at the current technology level airborne wind energy systems can be as much as 10 times less expensive than conventional wind turbines for the same average power output.<ref>{{cite doi|10.1016/j.energy.2013.03.087}}</ref><ref name="AWEbook">"Airborne Wind Energy" (Springer, 2013), Ahrens, Uwe; Diehl, Moritz; Schmehl, Roland (Eds.), chapter 13</ref>
 
=== Incentives and community benefits ===
[[File:GreenMountainWindFarm Fluvanna 2004.jpg|thumb|right|U.S. landowners typically receive $3,000–$5,000 annual rental income per wind turbine, while farmers continue to grow crops or graze cattle up to the foot of the turbines.<ref name="nine" /> Shown: the [[Brazos Wind Farm]] in Texas.]]
[[File:Wind energy converter5.jpg|thumb||Some of the 6,000 wind turbines in California's [[Altamont Pass Wind Farm]] aided by tax incentives during the 1980s.<ref name="altamontPass" />]]
 
The U.S. wind industry generates tens of thousands of jobs and billions of dollars of economic activity.<ref name=usdept>{{cite web |url=http://www.nrel.gov/docs/fy12osti/49222.pdf |title=Strengthening America's Energy Security with Offshore Wind |date = February 2011|publisher=U.S. Department of Energy }}</ref> Wind projects provide local taxes, or payments in lieu of taxes and strengthen the economy of rural communities by providing income to farmers with wind turbines on their land.<ref name=nine /><ref>{{cite web
 
  | title = Direct Federal Financial Interventions and Subsidies in Energy in Fiscal Year 2010
  | work = Report
  | publisher = Energy Information Administration
  | date = 1 August 2011
  | url = http://www.eia.gov/analysis/requests/subsidy/
  | accessdate = 29 April 2012
 
}}</ref> Wind energy in many jurisdictions receives financial or other support to encourage its development. Wind energy benefits from [[subsidy|subsidies]] in many jurisdictions, either to increase its attractiveness, or to compensate for subsidies received by other forms of production which have significant negative externalities.
 
In the US, wind power receives a production tax credit (PTC) of 1.5¢/kWh in 1993 dollars for each kW·h produced, for the first ten years; at 2.2 cents per kW·h in 2012, the credit was renewed on 2 January 2012, to include construction begun in 2013.<ref>{{cite news
 
  | last = Gerhardt|first=Tina|date=6 January 2013
  | title = Wind Energy Gets a Boost Off Fiscal Cliff Deal
  | url = http://www.progressive.org/wind-energy-gets-boost-off-fiscal-cliff-deal
  | work = [[The Progressive]]
 
}}</ref> A 30% tax credit can be applied instead of receiving the PTC.<ref>{{cite web
 
|url=http://www.ucsusa.org/clean_energy/smart-energy-solutions/increase-renewables/production-tax-credit-for.html
|title=Production Tax Credit for Renewable Energy
|publisher=Ucsusa.org |date=2 January 2013
|accessdate=11 January 2013
 
}}</ref><ref>{{cite web
 
|url=http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=US13F&re=1&ee=1
|title=Renewable Electricity Production Tax Credit (PTC)
|publisher=Dsireusa.org
 
}}</ref> Another tax benefit is [[accelerated depreciation]]. Many American states also provide incentives, such as exemption from property tax, mandated purchases, and additional markets for "[[Renewable Energy Certificates|green credits]]".<ref>{{cite web|url=http://www.dsireusa.org/summarytables/finre.cfm |title=Financial Incentives for Renewable Energy |publisher=Dsireusa.org }}</ref> The [[Energy Improvement and Extension Act of 2008]] contains extensions of credits for wind, including microturbines. Countries such as [[Wind Power Production Incentive|Canada]] and Germany also provide incentives for wind turbine construction, such as tax credits or minimum purchase prices for wind generation, with assured grid access (sometimes referred to as [[feed-in tariff]]s). These feed-in tariffs are typically set well above average electricity prices.<ref>{{cite web
 
|url=http://www.renewableenergyworld.com/rea/news/article/2012/11/italian-small-wind-growing-with-feed-in-tariffs |title=Italian Small Wind Growing with Feed-in Tariffs
|publisher=Renewableenergyworld.com
|author=Gipe, Paul
|date=27 November 2012
 
}}</ref><ref>{{cite web
 
|url=http://web.archive.org/web/20130502230536/http://www.cmia.net/Portals/0/Repository/GWEC%20China%20wind%20tariffs.57301d14-f357-4176-9ebb-7d6921a7ef9d.pdf
|title=The Development of Wind Power Tariffs in China
|format=PDF }}</ref> {{As of |December 2013}}, US Senator [[Lamar Alexander]] and other senators are arguing that the "wind energy production tax credit should be allowed to expire at the end of 2013."<ref name="2013 TNT 243-20 SENATORS SAY WIND ENERGY CREDIT SHOULD BE ALLOWED TO EXPIRE.">{{cite web | title=2013 TNT 243-20 SENATORS SAY WIND ENERGY CREDIT SHOULD BE ALLOWED TO EXPIRE. | publisher=Tax Analysts | date=December 17, 2013 | accessdate=18 December 2013 | author=Alexander, Lamar}}</ref>
 
Secondary market forces also provide incentives for businesses to use wind-generated power, even if there is a [[Renewable Energy Certificates|premium price for the electricity]]. For example, [[Corporate social responsibility|socially responsible manufacturers]] pay utility companies a premium that goes to subsidize and build new wind power infrastructure. Companies use wind-generated power, and in return they can claim that they are undertaking strong "green" efforts. In the US the organization Green-e monitors business compliance with these renewable energy credits.<ref name="green-e" />
 
== Environmental effects ==
{{Main|Environmental impact of wind power}}
[[File:Wb deichh drei kuhs.jpg|thumb|left|According to the manager of this wind farm, livestock ignore wind turbines,
 
<ref name="livestock_ignore" /> and continue to graze as they did before wind turbines were installed.]]
 
Compared to the environmental impact of traditional energy sources, the environmental impact of wind power is relatively minor in terms of pollution. Wind power consumes no fuel, and emits no [[air pollution]], unlike fossil fuel power sources. The energy consumed to manufacture and transport the materials used to build a wind power plant is equal to the new energy produced by the plant within a few months. While a wind farm may cover a large area of land, many land uses such as agriculture are compatible, with only small areas of turbine foundations and infrastructure made unavailable for use.<ref name=mar /><ref name="windmeasurementinternational">{{cite web
 
| url= http://www.windmeasurementinternational.com/wind-info/wind-energy_faq.php
| title=FAQ
| publisher=Wind Measurement International
| accessdate=11 January 2013}}</ref>
 
There are reports of bird and bat mortality at wind turbines as there are around other artificial structures. The scale of the ecological impact may<ref name="Eilperin">{{cite news
 
| url = http://www.washingtonpost.com/wp-dyn/content/article/2009/04/15/AR2009041503622_2.html?hpid=topnews&sid=ST2009041602328
| title = Renewable Energy's Environmental Paradox
| last = Eilperin | first= Juliet |coauthors= Steven Mufson
| date = 16 April 2009
| work = [[The Washington Post]] |publisher=
| accessdate=17 April 2009
 
}}</ref> or may not<ref name="rspb" /> be significant, depending on specific circumstances. Although many artificial structures can kill birds, wind power has a disproportionate effect on certain endangered bird species.<ref name="nature">{{cite journal
 
| last=Subramanian | first=Meera
| title=The trouble with turbines: An ill wind 
| journal=Nature
|date=20 June 2012
|bibcode=2012Natur.486..310S
|volume=486
|pages=310–1
|doi=10.1038/486310a
|pmid=22722172
|issue=7403
 
}}</ref> An especially vulnerable group are [[Bird of prey|raptors]], which are slow to reproduce and favor the high wind speed corridors that wind turbine companies build turbines in, to maximize energy production.<ref name="nature" />  Although they have a negligible effect on most birds, in some locations there is a disproportionate effects on some birds of conservation concern, such as the [[golden eagle]] and [[Bird of prey|raptor]] species.<ref name="nature" />
 
However, a large [[meta-analysis]] of 616 individual studies on electricity production and its effects on avian mortality concluded that the most visible impacts of wind technology are not necessarily the most flagrant ones, as:<ref name="Sovacool-2009">{{cite journal
 
|doi=10.1016/j.renene.2012.01.074
  | last = [[Benjamin K. Sovacool|Sovacool]]  | first =Benjamin K
  | title = The Avian Benefits of Wind Energy: A 2009 Update
  | year = 2012
  | journal=Renewable Energy
  | volume=49
  | pages=19
 
}}</ref>{{cquote|
 
Wind turbines seem to present a significant threat as all their negative externalities are concentrated in one place, while those from conventional and nuclear fuel cycles are spread out across space and time. Avian mortality and wind energy has consequently received far more attention and research than the avian deaths associated with coal, oil, natural gas and nuclear power generators [although] study suggests that wind energy may be the least harmful to birds.}}
 
Prevention and mitigation of wildlife fatalities, and protection of [[peat bogs]],<ref name="blanketpeat" /> affect the siting and operation of wind turbines.
 
There are anecdotal reports of negative effects from noise on people who live very close to wind turbines. Peer-reviewed research has generally not supported these statements.<ref name='CanWEA09'>W. David Colby, Robert Dobie, Geoff Leventhall, David M. Lipscomb, Robert J. McCunney, Michael T. Seilo, Bo Søndergaard. [http://www.canwea.ca/pdf/talkwind/Wind_Turbine_Sound_and_Health_Effects.pdf "Wind Turbine Sound and Health Effects: An Expert Panel Review"], Canadian Wind Energy Association, December 2009.</ref>
 
== Politics ==
 
=== Central government ===
 
Fossil fuels are [[energy subsidies|subsidized by many governments]],{{citation needed|date=December 2013}} and wind power and other forms of renewable energy are also often subsidized. For example a 2009 study by the Environmental Law Institute<ref>{{cite web
 
|url=http://www.elistore.org/Data/products/d19_07.pdf
|title=Estimating U.S. Government Subsidies to Energy Sources: 2002–2008
|publisher=Environmental Law Institute
|date=September 2009
|format=PDF
|accessdate=31 October 2012
 
}}</ref> assessed the size and structure of U.S. energy subsidies over the 2002–2008 period.  The study estimated that subsidies to fossil-fuel based sources amounted to approximately $72 billion over this period and subsidies to renewable fuel sources totalled $29 billion. In the United States, the federal government has paid US$74&nbsp;billion for energy subsidies to support [[R&D]] for [[nuclear power]] ($50 billion) and [[fossil fuels]] ($24 billion) from 1973 to 2003.  During this same time frame, [[renewable energy]] technologies and [[efficient energy use|energy efficiency]] received a total of US$26&nbsp;billion.  It has been suggested that a subsidy shift would help to level the playing field and support growing energy sectors, namely [[solar power]], wind power, and [[biofuels]].<ref name=per />  History shows that no energy sector was developed without subsidies.<ref name=per>Pernick, Ron and Wilder, Clint (2007). ''[[The Clean Tech Revolution]]: The Next Big Growth and Investment Opportunity'', p. 280.</ref>
 
According to the [[International Energy Agency]] (IEA) (2011), energy subsidies artificially lower the price of energy paid by consumers, raise the price received by producers or lower the cost of production. "Fossil fuels subsidies costs generally outweigh the benefits. Subsidies to renewables and low-carbon energy technologies can bring long-term economic and environmental benefits".<ref name=IEA-FS2011>{{cite web|url=http://www.worldenergyoutlook.org/docs/weo2011/factsheets.pdf |title=World Energy Outlook 2011 Factsheet How will global energy markets evolve to 2035?|archiveurl=http://web.archive.org/web/20120204112700/http://www.worldenergyoutlook.org/docs/weo2011/factsheets.pdf|archivedate=4 February 2012 |publisher=IEA |date=November 2011}}</ref> In November 2011, an IEA report entitled ''Deploying Renewables 2011'' said "subsidies in green energy technologies that were not yet competitive are justified in order to give an incentive to investing into technologies with clear environmental and energy security benefits". The IEA's report disagreed with claims that renewable energy technologies are only viable through costly subsidies and not able to produce energy reliably to meet demand.
 
In the US, the wind power industry has recently increased its lobbying efforts considerably, spending about $5 million in 2009 after years of relative obscurity in Washington.<ref name="LobbyingAfter" /> By comparison, the US nuclear industry alone spent over $650 million on its lobbying efforts and campaign contributions during a single ten-year period ending in 2008.<ref name="spendingOnNuclear" /><ref>Ward, Chip. (5 March 2010) [http://articles.latimes.com/2010/mar/05/opinion/la-oe-ward5-2010mar05 Nuclear Power&nbsp;– Not A Green Option], [[Los Angeles Times]].</ref><ref>Pasternak, Judy (24 January 2010) [http://investigativereportingworkshop.org/investigations/nuclear-energy-lobbying-push/story/nuclear-energy-working-hard-win-support/ Nuclear Energy Lobby Working Hard To Win Support], [[The McClatchy Company|McClatchy Newspapers]] co-published with the [[American University School of Communication]].</ref>
 
Following the [[2011 Japanese nuclear accidents]], Germany's federal government is working on a new plan for increasing [[Efficient energy use|energy efficiency]] and [[renewable energy commercialization]], with a particular focus on offshore wind farms. Under the plan, large wind turbines will be erected far away from the coastlines, where the wind blows more consistently than it does on land, and where the enormous turbines won't bother the inhabitants. The plan aims to decrease Germany's dependence on energy derived from coal and nuclear power plants.<ref>{{cite web |url=http://www.spiegel.de/international/germany/0,1518,752791,00.html |title=Will Nuke Phase-Out Make Offshore Farms Attractive? |author=Schultz, Stefan |date=23 March 2011 |work=Der Spiegel }}</ref>
 
Commenting on the [[Energy policy of the European Union|EU's 2020 renewable energy target]], economist Professor [[Dieter Helm]] is critical of how the costs of wind power are cited by lobbyists. Helm also says that the problem of intermittent supply will probably lead to another [[dash for gas]] or dash for coal in Europe, possibly with a negative impact on [[energy security]].<ref>{{cite journal|last=Helm |first=Dieter|date=October 2009|title=EU climate-change policy—a critique|journal=The Economics and Politics of Climate Change|publisher=OUP|url=http://www.dieterhelm.co.uk/sites/default/files/SS_EU_CC_Critique_0.pdf}}</ref> A [[House of Lords]] [[Select Committee (Westminster System)|Select Committee]] report (2008) on renewable energy in the UK reported a "concern over the prospective role of wind generated and other intermittent sources of electricity in the UK, in the absence of a break-through in electricity storage technology or the integration of the UK grid with that of continental Europe".<ref name="FourthReport" />
 
=== Public opinion ===
[[File:Public Opinion Wind Farm Redington Mountain.jpg|thumb|left|Environmental group members are both more in favor of wind power (74%) as well as more opposed (24%). Few are undecided.]]
 
Surveys of public attitudes across [[Europe]] and in many other countries show strong public support for wind power.<ref name=com /><ref name=vipublic>{{cite web|url=http://www.ewea.org/fileadmin/ewea_documents/documents/publications/WD/WD22vi_public.pdf |title=A Summary of Opinion Surveys on Wind Power |format=PDF |accessdate=17 January 2012}}</ref><ref name=eon>{{cite web|url=http://web.archive.org/web/20120504073200/http://eon-uk.com/generation/publicattitudes.aspx |title=Public attitudes to wind farms |publisher=Eon-uk.com |date=28 February 2008 |accessdate=17 January 2012}}</ref> About 80% of EU citizens support wind power.<ref name=thefacts>{{cite web |url=http://www.wind-energy-the-facts.org/en/environment/chapter-6-social-acceptance-of-wind-energy-and-wind-farms/ |title=The Social Acceptance of Wind Energy |work=European Commission }}</ref>
In [[Germany]], where wind power has gained very high social acceptance, hundreds of thousands of people have invested in citizens' wind farms across the country and thousands of small and medium sized enterprises are running successful businesses in a new sector that in 2008 employed 90,000 people and generated 8% of Germany's electricity.<ref name=emp>{{cite web|url=http://dsc.discovery.com/technology/my-take/community-wind-farm.html |title=Community Power Empowers|archiveurl=http://web.archive.org/web/20090325021002/http://dsc.discovery.com/technology/my-take/community-wind-farm.html |archivedate=25 March 2009|publisher=Dsc.discovery.com |date=26 May 2009 |accessdate=17 January 2012}}</ref><ref name=soc>{{cite web|url=http://nccnsw.org.au/index2.php?option=com_content&do_pdf=1&id=2148 |title=Community Wind Farms|archiveurl=http://web.archive.org/web/20080720132956/http://nccnsw.org.au/index2.php?option=com_content&do_pdf=1&id=2148|archivedate=20 July 2008}}</ref> Although wind power is a popular form of energy generation, the construction of wind farms is not universally welcomed, often for [[aesthetics|aesthetic]] reasons.<ref name=mar /><ref name=com /><ref name=vipublic /><ref name=eon /><ref name=thefacts /><ref>{{cite web|title=Carbon footprint of electricity generation|publisher=UK Parliamentary Office of Science and Technology|date=October 2006|url=http://www.parliament.uk/documents/post/postpn268.pdf|location=Postnote Number 268|accessdate=7 April 2012}}</ref><ref name=pollingreport>{{cite web|url=http://www.pollingreport.com/energy.htm|title=Energy|accessdate=31 October 2012}}</ref>
 
In [[Spain]], with some exceptions, there has been little opposition to the installation of inland wind parks. However, the projects to build offshore parks have been more controversial.<ref>{{cite journal
| last = Cohn
| first = Laura
| coauthors = Vitzhum, Carlta; Ewing, Jack
| title = Wind power has a head of steam
| journal = European Business.
| date = 11 July 2005
| url =
| id =
}}</ref> In particular, the proposal of building the biggest offshore wind power production facility in the world in southwestern Spain in the coast of [[Cadiz|Cádiz]], on the spot of the 1805 [[Battle of Trafalgar]].<ref name="Engineer2003">{{cite journal
| title = Grave developments for battle site
| journal = The Engineer.
| page = 6
| date = 13 June 2003
| url =
| id =
}}</ref>  has been met with strong opposition who fear for tourism and fisheries in the area,<ref>[http://www.diariodesevilla.es/article/andalucia/409153/la/eolicas/preparan/suinmersion.html Las eólicas preparan su inmersión] 4 June 2009 {{es icon}}</ref> and because the area is a war grave.<ref name="Engineer2003" />
 
{| style="border:solid 1px #aaa;" cellpadding="7" cellspacing="0" class="floatright"
|+'''Which should be increased in Scotland?'''<ref>Braunholtz, Simon (2003) [http://www.scotland.gov.uk/Resource/Doc/47133/0014639.pdf Public Attitudes to Windfarms]. Scottish Executive Social Research.</ref>
|-
|<timeline>
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DateFormat = x.y
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color:green width:30
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In a survey conducted by [[Angus Reid Public Opinion|Angus Reid Strategies]] in October 2007, 89 per cent of respondents said that using renewable energy sources like wind or solar power was positive for [[Canada]], because these sources were better for the environment. Only 4 per cent considered using renewable sources as negative since they can be unreliable and expensive.<ref>{{cite web|url=http://www.angus-reid.com/uppdf/ARS_Energy.pdf |title=Canadians favour energy sources that are better for the environment|archiveurl=http://web.archive.org/web/20090318232442/http://www.angus-reid.com/uppdf/ARS_Energy.pdf|archivedate=18 March 2009}}</ref> According to a Saint Consulting survey in April 2007, wind power was the alternative energy source most likely to gain public support for future development in Canada, with only 16% opposed to this type of energy. By contrast, 3 out of 4 Canadians opposed nuclear power developments.<ref>{{cite web|url=http://www.tscg.biz/media/releases/Saint%20Index%20Canada%202007%20Energy.pdf |title=Wind power developments are least likely to be opposed by Canadians&nbsp;– Nuclear power opposed by most |format=PDF |publisher=Saint Consulting}}</ref>
 
A 2003 survey of residents living around [[Scotland]]'s 10 existing wind farms found high levels of community acceptance and strong support for wind power, with much support from those who lived closest to the wind farms. The results of this survey support those of an earlier Scottish Executive survey 'Public attitudes to the Environment in Scotland 2002', which found that the Scottish public would prefer the majority of their electricity to come from renewables, and which rated wind power as the cleanest source of renewable energy.<ref>{{cite web|url=http://www.bwea.com/media/news/goodneighbours.html |title=Wind farms make good neighbours|archiveurl=http://web.archive.org/web/20120215024756/http://www.bwea.com/media/news/goodneighbours.html|archivedate=15 February 2012}}</ref> A survey conducted in 2005 showed that 74% of people in Scotland agree that wind farms are necessary to meet current and future energy needs. When people were asked the same question in a Scottish renewables study conducted in 2010, 78% agreed. The increase is significant as there were twice as many wind farms in 2010 as there were in 2005. The 2010 survey also showed that 52% disagreed with the statement that wind farms are "ugly and a blot on the landscape". 59% agreed that wind farms were necessary and that how they looked was unimportant.<ref>{{cite web |url=http://www.bbc.co.uk/news/uk-scotland-11569466 |title='Rise in Scots wind farm support' |date=19 October 2010 }}</ref> Scotland is planning to obtain 100% of electricity from renewable sources by 2020.<ref>{{cite journal |url=https://windenergyigert.umass.edu/sites/windenergyigert/files/OFFSHORE%20WIND%20SCOTLAND%202012.pdf |title=An investigation into the potential barriers facing the development of offshore wind energy in Scotland: Case study – Firth of Forth offshore wind farm|doi=10.1016/j.rser.2012.03.018 |year=2012 |last1=o’Keeffe |first1=Aoife |last2=Haggett |first2=Claire |journal=Renewable and Sustainable Energy Reviews |volume=16 |issue=6 |pages=3711}}</ref>
 
=== Community ===
[[File:Wind tubines cumbria.JPG|thumb|Wind turbines such as these, in [[Cumbria]], England, have been opposed for a number of reasons, including aesthetics, by some sectors of the population.<ref>{{cite web |url=http://www.visitcumbria.com/wc/windfarms.htm |title=Wind Farms in Cumbria |accessdate=3 October 2008}}</ref><ref>{{cite news |url=http://news.bbc.co.uk/1/hi/business/3661728.stm |title=Wind Turbulence over turbines in Cumbria |last=Arnold |first=James |publisher=BBC News |date=20 September 2004}}</ref>]]
{{See also|Community debate about wind farms}}
 
Many wind power companies work with local communities to reduce environmental and other concerns associated with particular wind farms.<ref>{{cite web |url=http://www.renewableenergyaccess.com/rea/news/story?id=48671 |title=Group Dedicates Opening of 200 MW Big Horn Wind Farm: Farm incorporates conservation efforts that protect wildlife habitat |publisher=Renewableenergyaccess.com |accessdate=17 January 2012}}</ref><ref>{{cite web |first=Jeanette |last=Fisher |url=http://environmentpsychology.com/wind_power_midamerican's_intrepid_wind_farm1.htm |title=Wind Power: MidAmerican's Intrepid Wind Farm |publisher=Environmentpsychology.com}}</ref><ref>{{cite web |url=http://web.archive.org/web/20080721003610/http://www.agl.com.au/environment/sustainability/Pages/StakeholderEngagement.aspx |title=Stakeholder Engagement |publisher=Agl.com.au |date=19 March 2008}}</ref> In other cases there is [[Community wind energy|direct community ownership of wind farm projects]].  Appropriate government consultation, planning and approval procedures also help to minimize environmental risks.<ref name=com>{{cite web |url=http://www.ewea.org/fileadmin/ewea_documents/documents/press_releases/factsheet_environment2.pdf |publisher=Renewable Energy House|title=Wind Energy and the Environment |format=PDF |accessdate=17 January 2012}}</ref><ref>{{cite web |url=http://www.environment.gov.au/settlements/renewable/publications/pubs/wind-discussionpaper.pdf |title=National Code for Wind Farms |publisher=Environment.gov.au |accessdate=17 January 2012}}</ref><ref>{{cite web |url=http://www.publish.csiro.au/?act=view_file&file_id=EC140p6a.pdf |title=New standard and big investment for wind energy |publisher=Publish.csiro.au |date=17 December 2007 }}</ref> Some may still object to wind farms<ref name="wind-watch.org" /> but, according to [[The Australia Institute]], their concerns should be weighed against the need to address the threats posed by [[climate change]] and the opinions of the broader community.<ref>The Australia Institute (October 2006) [http://www.tai.org.au/documents/dp_fulltext/DP91.pdf Wind Farms The facts and the fallacies] Discussion Paper No. 91, ISSN 1322-5421, p. 28.</ref>
 
In America, wind projects are reported to boost local tax bases, helping to pay for schools, roads and hospitals. Wind projects also revitalize the economy of rural communities by providing steady income to farmers and other landowners.<ref name=nine />
 
In the UK, both the [[National Trust]] and the [[Campaign to Protect Rural England]] have expressed concerns about the effects on the rural landscape caused by inappropriately sited wind turbines and wind farms.<ref>[http://www.bbc.co.uk/news/uk-england-northamptonshire-17367028 "Wind farm to be built near a Northamptonshire heritage site"], ''BBC News'', 14 March 2012. Retrieved 20 March 2012.</ref><ref>{{cite web |url=http://www.edp24.co.uk/news/environment/cpre_calls_for_action_over_proliferation_of_wind_turbines_1_1363291 |title=CPRE calls for action over 'proliferation' of wind turbines |last=Hill |first=Chris |date=30 April 2012 |work=EDP 24 |publisher=Archant community Media Ltd }}</ref>
 
Some wind farms have become tourist attractions. The [[Whitelee Wind Farm]] Visitor Centre has an exhibition room, a learning hub, a café with a viewing deck and also a shop. It is run by the [[Glasgow Science Centre]].<ref>{{cite web |url=http://www.whiteleewindfarm.co.uk/visitor_centre |title=Whitelee Windfarm |work=Scottish Power Renewables }}</ref>
 
In Denmark, a loss-of-value scheme gives people the right to claim compensation for loss of value of their property if it is caused by proximity to a wind turbine. The loss must be at least 1% of the property's value.<ref name="Danish-loss-of-value-scheme" />
 
Despite this general support for the concept of wind power in the public at large, [[Environmental effects of wind power|local opposition]] often exists and has delayed or aborted a number of projects.<ref>{{cite journal|url=http://www.shef.ac.uk/polopoly_fs/1.88117!/file/Understanding-wind-farm-opposition---Dr-Chris-Jones-PDF-674K-.pdf |title=Understanding 'local' opposition to wind development in the UK How big is a backyard? |doi=10.1016/j.enpol.2010.01.051|year=2010|last1=Jones|first1=Christopher R.|last2=Richard Eiser|first2=J.|journal=Energy Policy|volume=38|issue=6|pages=3106}}</ref><ref>[http://www.wind-works.org/articles/tilting.html Tilting at Windmills: Public Opinion Toward Wind Energy]. Wind-works.org. Retrieved on 1 October 2013.</ref><ref>Yates, Ysabel (15 October 2012) [http://www.ecomagination.com/testing-the-waters-gaining-public-support-for-offshore-wind Testing the Waters: Gaining Public Support for Offshore Wind]. ecomagination.com</ref>
 
While aesthetic issues are subjective and some find wind farms pleasant and optimistic, or symbols of [[energy security|energy independence]] and local prosperity, protest groups are often formed to attempt to block new wind power sites for various reasons.<ref name="wind-watch.org">{{cite web|url=http://www.wind-watch.org/affiliates.php |title=Wind Energy Opposition and Action Groups |publisher=Wind-watch.org |date= |accessdate=11 January 2013}}</ref><ref name="guardian.co.uk" /><ref name=guardianQA />
 
This type of opposition is often described as [[NIMBY]]ism,<ref>{{cite news| url=http://www.thestar.com/comment/article/519708 | work=The Star | location=Toronto | title=Windmills vs. NIMBYism | date=20 October 2008}}</ref> but research carried out in 2009 found that there is little evidence to support the belief that residents only object to renewable power facilities such as wind turbines as a result of a "Not in my Back Yard" attitude.<ref>{{cite web|url=http://www.businessgreen.com/bg/news/1807322/wind-industry-avoid-branding-opponents-nimbys|title=Wind industry should avoid branding opponents "Nimbys" |last=Donoghue |first=Andrew |date=30 July 2009 |work=Business Green |publisher=Business Green |accessdate=13 April 2012}}</ref>
 
== Small-scale wind power ==
{{Further|Microgeneration}}
[[File:Tassa 5KW 2 ElectronSolarEnergy2.jpg|thumb|left|A 5 kilowatt [[vertical axis wind turbine]]]]
 
Small-scale wind power is the name given to wind generation systems with the capacity to produce up to 50&nbsp;kW of electrical power.<ref name="smallScaleCarbonTrust" /> Isolated communities, that may otherwise rely on [[Diesel generator|diesel]] generators, may use wind turbines as an alternative. Individuals may purchase these systems to reduce or eliminate their dependence on grid electricity for economic reasons, or to reduce their [[carbon footprint]]. Wind turbines have been used for household electricity generation in conjunction with [[Battery (electricity)|battery]] storage over many decades in remote areas.<ref name="Dodge" />
 
Grid-connected domestic wind turbines may use [[grid energy storage]], thus replacing purchased electricity with locally produced power when available. The surplus power produced by domestic microgenerators can, in some jurisdictions, be fed into the network and sold to the utility company, producing a retail credit for the microgenerators' owners to offset their energy costs.<ref name="SmallElectricity" /><ref name="home-made" />
 
Off-grid system users can either adapt to intermittent power or use batteries, [[photovoltaic]] or diesel systems to supplement the wind turbine. Equipment such as parking meters, traffic warning signs, street lighting, or wireless Internet gateways may be powered by a small wind turbine, possibly combined with a photovoltaic system, that charges a small battery replacing the need for a connection to the power grid.<ref>{{cite web|url=http://cleantechnica.com/2009/05/13/exploiting-the-downsides-of-wind-and-solar/|title=Wind, Solar-Powered Street Lights Only Need a Charge Once Every Four Days|last=Kart|first=Jeff|date=13 May 2009|work=Clean Technica|publisher=Clean Technica|accessdate=30 April 2012}}</ref>
 
In locations near or around a group of high-rise buildings, wind shear generates areas of intense turbulence, especially at street-level.<ref name="UrbanWindDefinition" /> The risks associated with mechanical or catastrophic failure have thus plagued urban wind development in densely populated areas, rendering the costs of insuring urban wind systems prohibitive.<ref name="An_Urban_Experiment_in_Renewable_Energy" />
Moreover, quantifying the amount of wind in urban areas has been difficult, as little is known about the actual wind resources of towns and cities.<ref name="WindyCities" />
 
A [[Carbon Trust]] study into the potential of small-scale wind energy in the UK, published in 2010, found that small wind turbines could provide up to 1.5 terawatt hours (TW·h) per year of electricity (0.4% of total UK electricity consumption), saving 0.6 million tonnes of carbon dioxide (Mt CO<sub>2</sub>) emission savings. This is based on the assumption that 10% of households would install turbines at costs competitive with grid electricity, around 12 pence (US 19 cents) a kW·h.<ref name="CarbonSmallTrust" /> A report prepared for the UK's government-sponsored [[Energy Saving Trust]] in 2006, found that home power generators of various kinds could provide 30 to 40% of the country's electricity needs by 2050.<ref>{{cite journal|last=Hamer|first=Mick|date=21 January 2006|title=The rooftop power revolution |journal=New Scientist|publisher=Reed Business Information Ltd.|issue=2535|url=http://www.newscientist.com/article/mg18925351.400-the-rooftop-power-revolution.html?full=true#bx253514B1|accessdate=11 April 2012}}</ref>
 
[[Distributed generation]] from [[renewable resource]]s is increasing as a consequence of the increased awareness of [[climate change]]. The electronic interfaces required to connect renewable generation units with the [[utility]] system can include additional functions, such as the active filtering to enhance the power quality.<ref name="ActiveFiltering" />
{{-}}
 
== See also ==
{{Portal|Renewable energy|Energy|Sustainable development}}
 
{{div col|3}}
* [[Airborne wind turbine]]
* [[Controlled aerodynamic instability phenomena]]
* [[Copper in renewable energy#Copper in wind power generation|Copper in wind power generation]]
* [[Cost of electricity by source]]
* [[Crosswind kite power]]
* [[Design feasibility of Wind turbine systems]]
* [[Floating wind turbine]]
* [[High altitude wind power]]
* [[List of countries by electricity production from renewable sources]]
* [[List of energy storage projects]]
* [[List of wind turbine manufacturers]]
* [[Lists of offshore wind farms by country]]
* [[Lists of wind farms by country]]
* [[Outline of wind energy]]
* [[Renewable energy commercialization]]
* [[Vertical axis wind turbine]]
* [[Wind-diesel hybrid power system]]
* [[Wind lens]]
* [[Wind profiler]]
* [[Wind rights]]
* [[Wind turbines on public display]]
{{div col end}}
 
== Notes ==
<references group="nb" />
 
== References ==
{{Reflist|colwidth=25em|refs=
<ref name=increasesBy2010>{{cite web|url=http://www.gwec.net/index.php?id=30&no_cache=1&tx_ttnews%5Btt_news%5D=279&tx_ttnews%5BbackPid%5D=97&cHash=01e9c85e9f|title=Global wind capacity increases by 22% in 2010&nbsp;– Asia leads growth|archiveurl=http://web.archive.org/web/20120318203112/http://www.gwec.net/index.php?id=30&no_cache=1&tx_ttnews[tt_news]=279&tx_ttnews[backPid]=97&cHash=01e9c85e9f|archivedate=18 March 2012|publisher= Global Wind Energy Council|accessdate=14 May 2011|date=2 February 2011}}</ref>
 
<ref name=SmallElectricity>[http://www.aessolarenergy.com/sell_electricity.htm "Sell electricity back to the utility company"] Retrieved on 7 November 2008</ref>
 
<ref name=home-made>[http://www.thesundaytimes.co.uk/sto/Migration/article100906.ece Home-made energy to prop up grid] [[The Times]] 22 June 2008 Retrieved on 10 January 2013</ref>
 
<ref name=ceereCapInter>[http://www.ceere.org/rerl/about_wind/RERL_Fact_Sheet_2a_Capacity_Factor.pdf Wind Power: Capacity Factor, Intermittency, and what happens when the wind doesn't blow?]. Retrieved 24 January 2008.</ref>
 
<ref name=MassMaritime>[http://view2.fatspaniel.net/FST/Portal/LighthouseElectrical/maritime/HostedAdminView.html Massachusetts Maritime Academy&nbsp;— Bourne, Mass] This 660&nbsp;kW wind turbine has a capacity factor of about 19%.</ref>
 
<ref name=iesoOntarioWind>[http://www.ieso.ca/imoweb/marketdata/windpower.asp Wind Power in Ontario] These wind farms have capacity factors of about 28–35%.</ref>
 
<ref name=capFactors>{{cite web|url=http://www.rocks.org.hk/activity2009/Capacity_factor%5B1%5D.pdf |title=Capacity factor of wind power realized values vs. estimates |date=10 April 2009|accessdate=11 January 2013}}</ref>
 
<ref name=Windpowering>[http://www.windpoweringamerica.gov/pdfs/20_percent_wind_2.pdf WindpoweringAmerica.gov], 46. U.S. Department of Energy; Energy Efficiency and Renewable Energy "20% Wind Energy by 2030"</ref>
 
<ref name=ESB2004Study>ESB National Grid, Ireland's electric utility, in a 2004 study that, concluded that to meet the renewable energy targets set by the EU in 2001 would "increase electricity generation costs by a modest 15%"
 
{{cite web
| url= http://www.eirgrid.com/EirGridPortal/uploads/Publications/Wind%20Impact%20Study%20-%20main%20report.pdf
| title= Impact of Wind Power Generation in Ireland on the Operation of Conventional Plant and the Economic Implications
| date= February 2004 | format= PDF
| publisher= ESB National Grid
| page= 36|archiveurl = http://web.archive.org/web/20090325014258/http://www.eirgrid.com/EirGridPortal/uploads/Publications/Wind%20Impact%20Study%20-%20main%20report.pdf |archivedate = 29 March 2009 |quote=
| accessdate=23 July 2008 }}</ref>
 
<ref name=slogin>[http://www.nytimes.com/2008/08/27/business/27grid.html?_r=2&oref=slogin&oref=slogin Wind Energy Bumps Into Power Grid's Limits] Published: 26 August 2008</ref>
 
<ref name=altamontPass>{{cite web|url=http://www.ilr.tu-berlin.de/WKA/windfarm/altcal.html |title=Wind Plants of California's Altamont Pass|archiveurl=http://web.archive.org/web/20090426053651/http://www.ilr.tu-berlin.de/WKA/windfarm/altcal.html|archivedate=26 April 2009}}</ref>
 
<ref name=green-e>[https://speakerdeck.com/resourcesolutions/the-2010-green-e-verification-report The 2010 Green-e Verification Report] Retrieved on 20 May 2009</ref>
 
<ref name=FourthReport>
{{cite web
| date=12 November 2008
| title=Chapter 7: Recommendations and Conclusions. In: Economic Affairs&nbsp;– Fourth Report, Session 2007–2008. The Economics of Renewable Energy
| author=House of Lords Economic Affairs Select Committee
| publisher=UK Parliament website
| url=http://www.publications.parliament.uk/pa/ld200708/ldselect/ldeconaf/195/19510.htm
| accessdate=6 September 2009}}</ref>
 
<ref name=LobbyingAfter>
{{cite web
| date=30 March 2010
| title=Solar, Wind Power Groups Becoming Prominent Washington Lobbying Forces After Years of Relative Obscurity
| author=LaRussa, Cassandra
| publisher=OpenSecrets.org
| url=http://www.opensecrets.org/news/2010/03/solar-wind-power-becoming-prominent.html}}
 
</ref>
 
<ref name=spendingOnNuclear>[http://www.ucsusa.org/news/media_alerts/nuclear-industry-spent-millions-to-sell-congress-on-new-reactors-0343.html Nuclear Industry Spent Hundreds of Millions of Dollars Over the Last Decade to Sell Public, Congress on New Reactors, New Investigation Finds], [[Union of Concerned Scientists]], 1 February 2010. In turn, citing:
* Pasternak, Judy. [http://investigativereportingworkshop.org/investigations/nuclear-energy-lobbying-push/story/nuclear-energy-working-hard-win-support/ Nuclear Energy Lobby Working Hard To Win Support], American University School of Communication, Investigative Journalism Workshop, with McClatchy Newspapers, 24 January 2010. Retrieved 3 July 2010.</ref>
 
<ref name=smallScaleCarbonTrust>{{cite web|url=http://www.carbontrust.com/resources/reports/technology/small-scale-wind-energy |title=Small-scale wind energy |publisher=Carbontrust.co.uk |accessdate=29 August 2010}}</ref>
 
<ref name=UrbanWindDefinition>{{cite web|url=http://www.answers.com/topic/urban-wind |title=Urban Wind Definition at |publisher=Answers.com |accessdate=29 August 2010}}</ref>
 
<ref name=WindyCities>{{cite web|url=http://www.carbontrust.co.uk/News/presscentre/2007/230107_Smallscalwind.htm |title=Windy Cities? New research into the urban wind resource|archiveurl=http://web.archive.org/web/20080724084341/http://www.carbontrust.co.uk/News/presscentre/2007/230107_Smallscalwind.htm|archivedate=24 July 2008 |publisher=Carbontrust.co.uk |accessdate=29 August 2010}}</ref>
 
<ref name=CarbonSmallTrust>{{cite web|url=http://www.carbontrust.com/resources/reports/technology/small-scale-wind-energy|title= Smale scale wind energy|publisher=Carbontrust.com |accessdate=11 April 2012}}</ref>
 
<ref name=ActiveFiltering>{{cite journal|doi=10.1109/ICHQP.2002.1221533|title=10th International Conference on Harmonics and Quality of Power. Proceedings (Cat. No.02EX630)|chapter=Active filtering and load balancing with small wind energy systems|year=2002|last1=MacKen|first1=K.J.P.|last2=Green|first2=T.C.|last3=Belmans|first3=R.J.M.|isbn=0-7803-7671-4|volume=2|pages=776}}</ref>
 
<ref name=tacklingUS>
{{cite web| url=http://ases.org/images/stories/file/ASES/climate_change.pdf | title=Tackling Climate Change in the U.S |archiveurl=http://web.archive.org/web/20081126220129/http://www.ases.org/images/stories/file/ASES/climate_change.pdf |archivedate=26 November 2008 |format=PDF | publisher= American Solar Energy Society| date=January 2007| accessdate=5 September 2007 }}
</ref>
 
<ref name=NGestimates>The UK System Operator, [[National Grid (UK)]] have quoted estimates of balancing costs for 40% wind and these lie in the range £500-1000M per annum. "These balancing costs represent an additional £6 to £12 per annum on average consumer electricity bill of around £390."
 
{{cite web| work=National Grid | year=2008 | title=National Grid's response to the House of Lords Economic Affairs Select Committee investigating the economics of renewable energy|
url=http://www.parliament.uk/documents/upload/EA273%20National%20Grid%20Response%20on%20Economics%20of%20Renewable%20Energy.pdf|archiveurl=http://web.archive.org/web/20090325012754/http://www.parliament.uk/documents/upload/EA273%20National%20Grid%20Response%20on%20Economics%20of%20Renewable%20Energy.pdf|archivedate=25 March 2009}}
</ref>
 
<ref name=minnesota>A study commissioned by the state of Minnesota considered penetration of up to 25%, and concluded that integration issues would be manageable and have incremental costs of less than one-half-cent ($0.0045) per kW·h.
 
{{cite web
| url= http://www.puc.state.mn.us/docs/windrpt_vol%201.pdf
| title= Final Report&nbsp;– 2006 Minnesota Wind Integration Study
| date= 30 November 2006 | format= PDF
| archiveurl=http://web.archive.org/web/20071201192029/http://www.puc.state.mn.us/docs/windrpt_vol%201.pdf
| archivedate=1 December 2007
| publisher= The Minnesota Public Utilities Commission
| quote=
| accessdate=15 January 2008 }}</ref>
 
<ref name=sinclairMerz>Sinclair Merz ''Growth Scenarios for UK Renewables Generation and Implications for Future Developments and Operation of Electricity Networks'' BERR Publication URN 08/1021 June 2008</ref>
 
<ref name=clavertonReliable>{{cite web|url=http://www.claverton-energy.com/download/316/ |title=Is wind power reliable? |archiveurl=http://web.archive.org/web/20100605111723/http://www.claverton-energy.com/download/316/ |archivedate=5 June 2010 |accessdate=29 August 2010}}</ref>
 
<ref name=dinorwig>{{cite web|url=http://www.thegreenage.co.uk/greencommercial/hydroelectric-power/dinorwig-hydroelectric-plant |title=Dinorwig Hydroelectric Plant, Wales |publisher=Thegreenage.co.uk |date= |accessdate=11 January 2013}}</ref>
 
<ref name=futureStorage>The Future of Electrical Energy Storage: The economics and potential of new technologies 2/1/2009 ID RET2107622</ref>
 
<ref name=smallWindSystems>{{cite web|url=http://www.seco.cpa.state.tx.us/re/wind/smallwind.php |title=Small Wind Systems |publisher=Seco.cpa.state.tx.us |accessdate=29 August 2010}}</ref>
 
<ref name=eolica>{{cite web|url=http://www.ree.es/ingles/sala_prensa/web/notas_detalle.aspx?id_nota=230 |title=Wind produces more than 60% of the electricity consumed in Spain during the early hours of this morning |publisher=Ree.es |date= |accessdate=11 January 2013}}</ref>
 
<ref name=abbess>{{cite web|author=Abbess, Jo |url=http://www.claverton-energy.com/wind-energy-variability-new-reports.html |title=Wind Energy Variability and Intermittency in the UK |publisher=Claverton-energy.com |date=28 August 2009}}</ref>
 
<ref name="eirgrid renewables">{{cite web |url=http://www.eirgrid.com/renewables/ |title=Renewables |publisher=eirgrid.com |accessdate=22 November 2010}}</ref>
 
<ref name="eirgrid impact">{{cite web |url=http://www.eirgrid.com/media/2004%20wind%20impact%20report%20(for%20updated%202007%20report,%20see%20above).pdf |title=Impact of Wind Power Generation in Ireland on the Operation of Conventional Plant and the Economic Implications |publisher=eirgrid.com |date=February 2004 |accessdate=22 November 2010}}</ref>
 
<ref name=mysanantantonio>{{cite web|url=http://www.mysanantonio.com/news/weather/weatherwise/stories/MYSA092407.01A.State_windmills.3430a27.html |title=Quirky old-style contraptions make water from wind on the mesas of West Texas |publisher=Mysanantonio.com |archiveurl=http://web.archive.org/web/20100916054539/http://www.mysanantonio.com/news/MYSA092407_01A_State_windmills_3430a27_html15318.html|archivedate=16 September 2010|date=23 September 2007 |accessdate=29 August 2010}}</ref>
 
<ref name="ieawind">
{{cite web
| url= http://www.ieawind.org/AnnexXXV/Meetings/Oklahoma/IEA%20SysOp%20GWPC2006%20paper_final.pdf
| title= Design and Operation of Power Systems with Large Amounts of Wind Power
| author= Holttinen, Hannele ''et al.''
|date = September 2006|format= PDF |publisher=IEA Wind Summary Paper, Global Wind Power Conference 18–21 September 2006, Adelaide, Australia
}}</ref>
 
<ref name=salerno>Salerno, E., AWEA Director of Industry and Data Analysis, as quoted in Shahan, Z. (2011) [http://cleantechnica.com/2011/05/01/cost-of-wind-power-kicks-coals-butt-better-than-natural-gas-could-power-your-ev-for-0-70gallon/ Cost of Wind Power&nbsp;– Kicks Coal's Butt, Better than Natural Gas (& Could Power Your EV for $0.70/gallon)"] ''CleanTechnica.com''</ref>
 
<ref name="eiadoe">{{cite web| url= http://www.eia.doe.gov/oiaf/archive/ieo06/special_topics.html | title= International Energy Outlook |year=2006 |publisher= [[Energy Information Administration]]
| page= 66 |quote=}}</ref>
 
<ref name=ccc>Committee on Climate Change (May 2011) [http://hmccc.s3.amazonaws.com/Renewables%20Review/MML%20final%20report%20for%20CCC%209%20may%202011.pdf Costs of low-carbon generation technologies].</ref>
 
<ref name=juande>{{cite web |url=http://www.juandemariana.org/pdf/090327-employment-public-aid-renewable.pdf |title=Study of the effects on employment of public aid to renewable energy sources |publisher=juandemariana.org |date=March 2009 |accessdate=22 November 2010}}</ref>
 
<ref name=nrelemployment>{{cite web |url=http://www.nrel.gov/docs/fy09osti/46261.pdf |title=NREL Response to the Report Study of the Effects on Employment of Public Aid to Renewable Energy Sources from King Juan Carlos University (Spain) |publisher=nrel.gov |date=August 2009}}</ref>
 
<ref name=meritorder>{{cite web|url=http://isi.fraunhofer.de/isi/publ/download/isi07a18/merit-order-effect.pdf?pathAlias=/publ/downloads/isi07a18/merit-order-effect.pdf|archiveurl=http://www.webcitation.org/5sLyvXbZ6|archivedate=29 August 2010 |title=The Merit-Order Effect: A Detailed Analyis of the Price Effect of Renewable Electricity Generation on Spot Market Prices in Germany |format=PDF |accessdate=29 August 2010}}</ref>
 
<ref name=helming>Helming, Troy (2004) [http://web.archive.org/20071118125045/arizonaenergy.org/News&Events/Uncle%20Sam's%20New%20Year's%20Resolution.htm "Uncle Sam's New Year's Resolution"] ''ArizonaEnergy.org''</ref>
 
<ref name="GWEC_Market">{{cite web|url=http://gwec.net/wp-content/uploads/2012/06/Annual_report_2011_lowres.pdf |title=GWEC, Global Wind Report Annual Market Update 2011 |publisher=Gwec.net |accessdate=14 May 2011}}</ref>
 
<ref name="GWEC_Forcast">{{cite web|url=http://www.gwec.net/wp-content/uploads/2012/06/GWEO-2010-final.pdf |title=GWEC, Global Wind Energy Outlook 2010 |publisher=Gwec.net |accessdate=14 May 2011}}</ref>
 
<ref name="wwea">
{{cite web
| publisher = [[World Wind Energy Association]]
| title = World Wind Energy Report 2010
| format = PDF
| work = Report
| date = February 2011
| url = http://www.wwindea.org/home/images/stories/pdfs/worldwindenergyreport2010_s.pdf
| accessdate =8 August 2011}}</ref>
 
<ref name=wor>{{cite web|url=http://vitalsigns.worldwatch.org/vs-trend/wind-power-increase-2008-exceeds-10-year-average |title=Wind Power Increase in 2008 Exceeds 10-year Average Growth Rate |publisher=Worldwatch.org |accessdate=29 August 2010}}</ref>
 
<ref name=ren212011>{{cite web |url=http://germanwatch.org/klima/gsr2011.pdf |title=Renewables 2011: Global Status Report |author=[[REN21]] |year=2011 |page=11 }}</ref>
 
<ref name="Price">{{cite journal|last=Price|first=Trevor J|title=James Blyth&nbsp;– Britain's first modern wind power engineer|journal=Wind Engineering|volume=29|issue=3|pages=191–200|date=3 May 2005|doi=10.1260/030952405774354921}}
</ref>
 
<ref name=nine>American Wind Energy Association (2009) [http://www.slideshare.net/Calion/awea-annual-wind-report-2009 Annual Wind Industry Report, Year Ending 2008] p. 11</ref>
 
<ref name="eolicenergynews4082">{{cite web|url=http://www.eolicenergynews.org/?p=4082 |title=Spain becomes the first European wind energy producer after overcoming Germany for the first time |publisher=Eolic Energy News |date=31 December 2010 |accessdate=14 May 2011}}</ref>
 
<ref name=gwec2007>{{cite web|url=http://www.gwec.net/index.php?id=30&no_cache=1&tx_ttnews%5Btt_news%5D=121&tx_ttnews%5BbackPid%5D=4&cHash=f9b4af1cd0 |title=Continuing boom in wind energy&nbsp;– 20 GW of new capacity in 2007 |publisher=Gwec.net |accessdate=29 August 2010}}</ref>
 
<ref name=re>{{cite web|url=http://www.renewableenergyworld.com/rea/news/article/2009/03/btm-forecasts-340-gw-of-wind-by-2013?src=rss |title=BTM Forecasts 340-GW of Wind Energy by 2013 |publisher=Renewableenergyworld.com |date=27 March 2009 |accessdate=29 August 2010}}</ref>
 
<ref name=bt>BTM Consult (2009) [http://www.btm.dk/documents/pressrelease.pdf International Wind Energy Development World Market Update 2009]</ref>
 
<ref name=Danish-loss-of-value-scheme>{{cite web|url=http://www.ens.dk/sites/ens.dk/files/supply/renewable-energy/wind-power/Vindturbines%20in%20DK%20eng.pdf |title=Wind Turbines in Denmark|publisher=section 6.8, p. 22, Danish Energy Agency |format=PDF |date=November 2009|isbn=978-87-7844-821-7}}</ref>
 
<ref name="btm2010o">Madsen & Krogsgaard (22 November 2010) [http://btm.dk/news/offshore+wind+power+2010/?s=9&p=&n=39 Offshore Wind Power 2010] ''[[BTM Consult]]''.</ref>
 
<ref name=Demeo2005>
 
{{cite journal
| last1 = Demeo | first1 = E.A.
| last2 = Grant | first2 = W.
| last3 = Milligan | first3 = M.R.
| last4 = Schuerger | first4 = M.J.
| year = 2005
| title = Wind plant integration
| journal = Power and Energy Magazine, IEEE
| volume = 3
| issue = 6
| pages = 38–46
| doi = 10.1109/MPAE.2005.1524619
}}</ref>
 
<ref name=Zavadil2005>{{cite journal
| last1 = Zavadil | first1 = R.
| last2 = Miller | first2 = N.
| last3 = Ellis | first3 = A.
| last4 = Muljadi | first4 = E.
| year = 2005
| title = Making connections
| journal = Power and Energy Magazine, IEEE
| volume = 3
| issue = 6
| pages = 26–37
| doi = 10.1109/MPAE.2005.1524618
}}</ref>
 
<ref name="is windpower reliable">{{cite web|url=http://www.claverton-energy.com/is-wind-power-reliable-an-authoritative-article-from-david-millborrow-who-is-technically-experienced-and-numerate-unlike-many-other-commentators.html |title=Claverton-Energy.com |publisher=Claverton-Energy.com |accessdate=29 August 2010}}</ref>
 
<ref name="Mitchell 2006">Mitchell 2006.</ref>
 
<ref name="geothermal_incentive">
{{cite web
|url=http://www.capitalelec.com/Energy_Efficiency/ground_source/index.html
|title=Geothermal Heat Pumps
|publisher=[[Capital Electric Cooperative]]
|accessdate=5 October 2008
}}
</ref>
 
<ref name=windsun>Wood, Shelby (21 January 2008) [http://blog.oregonlive.com/pdxgreen/2008/01/wind_sun_join_forces_at_washin.html Wind + sun join forces at Washington power plant]. The Oregonian.</ref>
 
<ref name="cleveland_water_crib">
{{cite web
| url=http://www.development.cuyahogacounty.us/pdf_development/en-US/ExeSum_WindResrc_CleveWtrCribMntr_Reprt.pdf
| title=Lake Erie Wind Resource Report, Cleveland Water Crib Monitoring Site, Two-Year Report Executive Summary
| format=PDF
| publisher=Green Energy Ohio
| date=10 January 2008
| accessdate=27 November 2008
}} This study measured up to four times as much average wind power during winter as in summer for the test site.</ref>
 
<ref name="combined_power_plant">
{{cite web
| url=http://www.solarserver.de/solarmagazin/anlagejanuar2008_e.html
| title=The Combined Power Plant: the first stage in providing 100% power from renewable energy
|date=January 2008
| accessdate=10 October 2008
| publisher=SolarServer
}}</ref>
 
<ref name="Denmark">
{{cite web
| url= http://www.icevirtuallibrary.com/content/article/10.1680/cien.2005.158.2.66
| title= Why wind power works for Denmark
|date = May 2005 |publisher= [[Civil Engineering]]
|quote=
| accessdate=15 January 2008 }}
</ref>
 
<ref name="Czisch-Giebel">[http://www.risoe.dk/rispubl/reports/ris-r-1608_186-195.pdf Realisable Scenarios for a Future Electricity Supply based 100% on Renewable Energies] Gregor Czisch, University of Kassel, Germany and Gregor Giebel, Risø National Laboratory, Technical University of Denmark</ref>
 
<ref name="connecting_wind_farms">
{{cite web
| url=http://www.eurekalert.org/pub_releases/2007-11/ams-tpo112107.php
| title=The power of multiples: Connecting wind farms can make a more reliable and cheaper power source
| date=21 November 2007
}}</ref>
 
<ref name=Archer2007>{{cite journal
| doi = 10.1175/2007JAMC1538.1
| title = Supplying Baseload Power and Reducing Transmission Requirements by Interconnecting Wind Farms
| author = Archer, C. L.; Jacobson, M. Z.
| year = 2007
| journal = Journal of Applied Meteorology and Climatology
| volume = 46
| issue = 11
| pages = 1701–1717
| url = http://www.stanford.edu/group/efmh/winds/aj07_jamc.pdf
| publisher = [[American Meteorological Society]]
|bibcode = 2007JApMC..46.1701A }}</ref>
 
<ref name="BWEA">{{cite web|url=http://www.bwea.com/pdf/briefings/target-2005-small.pdf |title=BWEA report on onshore wind costs|archiveurl=http://web.archive.org/web/20120311101709/http://www.bwea.com/pdf/briefings/target-2005-small.pdf|archivedate=11 March 2012}}</ref>
 
<ref name="Patel">"Wind and Solar Power Systems&nbsp;— Design, analysis and Operation" (2nd ed., 2006), Mukund R. Patel, p. 303</ref>
 
<ref name="Jamieson">"Innovation in Wind Turbine Design" (2011), Peter Jamieson, p. 131</ref><ref name="livestock_ignore">
{{cite web
| url= http://www.uintacountyherald.com/V2_news_articles.php?heading=0&page=72&story_id=1299
| title =Capturing the wind
| first =Erin
| last =Buller
| date =11 July 2008
| publisher =Uinta County Herald
| accessdate =4 December 2008
}}"The animals don't care at all. We find cows and antelope napping in the shade of the turbines."&nbsp;– Mike Cadieux, site manager, Wyoming Wind Farm</ref>
 
<ref name=mar>{{cite web|url=http://solarwind.net.au/Documents/WindPowersStrength.pdf |title=Why Australia needs wind power |format=PDF |accessdate=7 January 2012}}</ref>
 
<ref name="Eilperin">
{{cite news
| url = http://www.washingtonpost.com/wp-dyn/content/article/2009/04/15/AR2009041503622_2.html?hpid=topnews&sid=ST2009041602328
| title = Renewable Energy's Environmental Paradox
| last = Eilperin | first= Juliet |coauthors= Steven Mufson
| date = 16 April 2009
|work=The Washington Post | accessdate=17 April 2009 }}
</ref>
 
<ref name="rspb">{{cite web
| url = http://www.rspb.org.uk/ourwork/policy/windfarms/index.asp
| title = Wind farms
| publisher = [[Royal Society for the Protection of Birds]]
| accessdate =7 September 2008
| date = 14 September 2005 }}</ref>
 
<ref name="blanketpeat">{{cite journal|last=Lindsay|first=Richard|date=October 2004|title=WIND FARMS AND BLANKET PEAT The Bog Slide of 16 October 2003 at Derrybrien, Co. Galway, Ireland|publisher=The Derrybrien Development Cooperatve Ltd|url=http://www.uel.ac.uk/erg/documents/Derrybrien.pdf|accessdate=20 May 2009}}</ref>
 
<ref name="An_Urban_Experiment_in_Renewable_Energy">
{{cite web
|url=http://www.greenbeanchicago.com/urban-experiment-renewable-energy/
|title=An Urban Experiment in Renewable Energy
|first=William
|last=Olson
|date=15 February 2010
|archiveurl=http://web.archive.org/web/20120514014914/http://www.greenbeanchicago.com/urban-experiment-renewable-energy/
|archivedate=14 May 2012
|accessdate=8 March 2010
}}</ref>
 
<ref name=guardianQA>Aldred, Jessica (10 December 2007) [http://www.guardian.co.uk/environment/2007/dec/10/windpower.renewableenergy Q&A: Wind Power], The Guardian.</ref>
 
<ref name="guardian.co.uk">Gourlay, Simon (12 August 2008) [http://www.guardian.co.uk/commentisfree/2008/aug/12/windpower.alternativeenergy Wind Farms Are Not Only Beautiful, They're Absolutely Necessary], The Guardian.</ref>
 
<!-- The following references appeared in the reflist but were not used in the prior text. Please return them to the reflist once they have been correctly cited in the main article.
<ref name=PerceptionOfNoise>{{cite journal|last=Pederson|first=Eja|date=December 2004|title=Perception and annoyance due to wind turbine noise—a dose–response relationship|publisher=Acoustic Society of America}}</ref>
<ref name=ie>[[International Energy Agency]] (2009) [http://www.ieawind.org/AnnualReports_PDF/2008/2008%20AR_small.pdf IEA Wind Energy: Annual Report 2008] p. 235.</ref>
<ref name="global_council">[http://gwec.net/wp-content/uploads/2012/06/GWEC_-_Global_Wind_Statistics_2011.pdf Global Wind Statistics] 2 July 2012</ref>
-->
}}
 
== External links ==
{{Commons category}}
* [http://www.wwindea.org/home/index.php/ World Wind Energy Association (WWEA)]
 
{{Good article}}
{{Wind power}}
{{Wind power by country}}
{{Electricity generation|state=collapsed}}
{{Application of wind energy}}
{{Renewable energy by country}}
{{Natural resources}}
 
[[Category:Wind power| ]]
[[Category:Renewable energy]]

Latest revision as of 07:02, 30 December 2014

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