What is Wind turbine?
[[File:Windmills D1-D4 (Thornton Bank).jpg|thumb|200px|Wind farm in the [[North Sea]] off [[Belgium]]]] A '''wind turbine''' is a [[rotate|rotating]] [[machine]] that transfers [[kinetic energy]] from the [[wind]] into [[mechanical energy]]. If the [[mechanical energy]] is used directly by machinery, such as for pumping water, cutting lumber or grinding stones, the machine is called a [[windmill]]. If the mechanical energy is instead converted to [[electric power|electricity]], the machine may be called a '''wind turbine generator (WTG), wind power unit (WPU)''', '''wind energy converter (WEC)''', or '''aerogenerator'''. == Turning the generator == The wind turbine's blades are turned by the wind. This turns a shaft turning slowly, at about 10-20 [[rpm]]<ref>Cleantech http://blog.cleantech.com/cleantech-investments/wind-turbines-–-what’s-under-the-hood/ {{Webarchive|url=https://web.archive.org/web/20160501153855/http://blog.cleantech.com/cleantech-investments/wind-turbines-%e2%80%93-what%e2%80%99s-under-the-hood/ |date=2016-05-01 }}</ref> with a high [[torque]]. The shaft goes into a reduction [[gear]]box with a ratio of about 1:50, although some wind turbine gearboxes can have a ratio of 1:100 or more. Some wind turbines may have no reduction gearbox at all, and have a ratio of 1:1.<ref>{{Cite news|url=https://www.popsci.com/technology/article/2010-03/next-gen-wind-turbine|title=How It Works: The Next-Gen Wind Turbine|work=Popular Science|access-date=2018-04-27|language=en}}</ref> The gearbox turns the generator more quickly, at around 1000 rpm, at a low [[torque]]. The [[generator]] creates electricity. This electricity is combined with any other wind turbines that may be in the same [[wind farm]]. This combined electricity may be used locally, or adjusted to match the electricity in the [[power grid]] and sent to the power grid. == Environmental Impact == Although wind turbines are a [[renewable resource|renewable]] source of energy and don't pollute the environment as a result of generating power, they hav