Editing Wind power (section)

== Wind energy resources ==
[[File:Mean Wind Speed.png|thumb|Global map of wind speed at 100 meters on land and around coasts.<ref name="global_wind_atlas">{{cite web | url=https://globalwindatlas.info | title=Global Wind Atlas | publisher=[[Technical University of Denmark]] (DTU) | access-date=23 November 2021 | archive-date=18 January 2019 | archive-url=https://web.archive.org/web/20190118095006/https://www.globalwindatlas.info/ | url-status=live }}</ref>]]
[[File: Lee Ranch Wind Speed Frequency.svg|thumb|upright=1.6|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.]]
[[File:Global_Map_of_Wind_Power_Density_Potential.png|thumb|Global map of wind power density potential<ref>{{Cite web |title=Global Wind Atlas |url=https://globalwindatlas.info/ |url-status=live |archive-url=https://web.archive.org/web/20190118095006/https://www.globalwindatlas.info/ |archive-date=18 January 2019 |access-date=14 June 2019}}</ref>]]
Wind is air movement in the Earth's [[Atmosphere of Earth|atmosphere]]. In a unit of time, say 1 second, the volume of air that had passed an area <math>A</math> is <math>Av</math>. If the air density is <math>\rho</math>, the flow rate of this volume of air is <math>\tfrac{M}{\Delta t}=\rho Av</math>, and the power transfer, or energy transfer per second is <math>P =\tfrac {1}{2}\tfrac{M}{\Delta t} v^{2}= \tfrac {1}{2}\rho A v^{3}</math>. Wind power is thus ''proportional'' to the ''third power'' of the wind speed; the available power increases eightfold when the wind speed doubles. Change of wind speed by a factor of 2.1544 increases the wind power by one order of magnitude (multiply by 10).

The global wind kinetic energy averaged approximately 1.50 MJ/m<sup>2</sup> over the period from 1979 to 2010, 1.31 MJ/m<sup>2</sup> in the Northern Hemisphere with 1.70 MJ/m<sup>2</sup> in the Southern Hemisphere. The atmosphere acts as a thermal engine, absorbing heat at higher temperatures, releasing heat at lower temperatures. The process is responsible for the production of wind kinetic energy at a rate of 2.46 W/m<sup>2</sup> thus sustaining the circulation of the atmosphere against friction.<ref>{{cite journal|url=http://dash.harvard.edu/bitstream/handle/1/13919173/A%2032-year%20Perspective%20on%20the%20Origin%20of%20Wind%20Energy%20in%20a%20warming%20Climate.pdf?sequence=1|title=A 32-year perspective on the origin of wind energy in a warming climate|journal=Renewable Energy|volume=77|pages=482–92|year=2015|doi=10.1016/j.renene.2014.12.045|last1=Huang|first1=Junling|last2=McElroy|first2=Michael B|bibcode=2015REne...77..482H |s2cid=109273683 |access-date=6 February 2015|archive-date=6 February 2015|archive-url=https://web.archive.org/web/20150206044746/http://dash.harvard.edu/bitstream/handle/1/13919173/A%2032-year%20Perspective%20on%20the%20Origin%20of%20Wind%20Energy%20in%20a%20warming%20Climate.pdf?sequence=1|url-status=live}}</ref>

Through [[wind resource assessment]], it is possible to estimate wind power potential globally, [[Wind power by country|by country]] or region, or for a specific site. The [[Global Wind Atlas]] provided by the [[Technical University of Denmark]] in partnership with the [[World Bank]] provides a global assessment of wind power potential.<ref name="global_wind_atlas" /><ref>[https://www.worldbank.org/en/news/press-release/2017/11/28/mapping-the-worlds-wind-energy-potential Mapping the World's Wind Energy Potential] {{Webarchive|url=https://web.archive.org/web/20180925180559/https://www.worldbank.org/en/news/press-release/2017/11/28/mapping-the-worlds-wind-energy-potential |date=25 September 2018 }} ''[[World Bank]]'', 28 November 2017.</ref><ref>[http://www.vindenergi.dtu.dk/english/news/2017/11/new-global-wind-atlas-to-be-presented-at-windeurope-conference New Global Wind Atlas to be presented at WindEurope Conference] {{Webarchive|url=https://web.archive.org/web/20180925180408/http://www.vindenergi.dtu.dk/english/news/2017/11/new-global-wind-atlas-to-be-presented-at-windeurope-conference |date=25 September 2018 }} ''[[Technical University of Denmark]]'', 21 November 2017.</ref>
Unlike 'static' wind resource atlases which average estimates of wind speed and power density across multiple years, tools such as [[Renewables.ninja]] provide time-varying simulations of wind speed and power output from different wind turbine models at an hourly resolution.<ref>{{cite journal|last1= Staffell |first1= Iain |last2= Pfenninger |first2= Stefan |title=Using bias-corrected reanalysis to simulate current and future wind power output|date=1 November 2016|journal= Energy |volume = 114 |pages = 1224–39 |doi = 10.1016/j.energy.2016.08.068|doi-access = free|bibcode= 2016Ene...114.1224S |hdl= 20.500.11850/120087 |hdl-access= free }}</ref> More detailed, site-specific assessments of wind resource potential can be obtained from specialist commercial providers, and many of the larger wind developers have in-house modeling capabilities.

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?|last=Hurley|first=Brian|publisher=Claverton Group|access-date=8 April 2012|archive-date=15 May 2012|archive-url=https://web.archive.org/web/20120515154047/http://www.claverton-energy.com/how-much-wind-energy-is-there-brian-hurley-wind-site-evaluation-ltd.html|url-status=live}}</ref> 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 prospective wind power sites, a probability distribution function is often fit to the observed wind speed data.<ref>{{cite journal | url= http://www.savenkov.org/publications/Savenkov_on_the_truncated_weibull_distribution_2009.pdf |author=Savenkov, M |year=2009 |title=On the truncated weibull distribution and its usefulness in evaluating potential wind (or wave) energy sites |journal=University Journal of Engineering and Technology |volume=1 |issue=1 |pages=21–25 |url-status=bot: unknown |archive-url=https://web.archive.org/web/20150222120957/http://www.savenkov.org/publications/Savenkov_on_the_truncated_weibull_distribution_2009.pdf |archive-date=22 February 2015}}</ref> 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://xn--drmstrre-64ad.dk/wp-content/wind/miller/windpower%20web/en/tour/wres/weibull.htm | title=Describing Wind Variations: Weibull Distribution | publisher=Danish Wind Industry Association | access-date=8 July 2021 | archive-date=2 August 2021 | archive-url=https://web.archive.org/web/20210802193222/http://xn--drmstrre-64ad.dk/wp-content/wind/miller/windpower%20web/en/tour/wres/weibull.htm | url-status=live }}</ref>