Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, windmills for mechanical power, windpumps for water pumping or drainage, or sails to propel ships.
The total amount of economically extractable power available from the wind is considerably more than present human power use from all sources.[3] At the end of 2010, worldwide nameplate capacity of wind-powered generators was 197 gigawatts (GW).[4] Wind power now has the capacity to generate 430 TWh annually, which is about 2.5% of worldwide electricity usage.[4][5] Over the past five years the average annual growth in new installations has been 27.6 percent. Wind power market penetration is expected to reach 3.35 percent by 2013 and 8 percent by 2018.[6][7] Several countries have already achieved relatively high levels of wind power penetration, such as 21% of stationary electricity production in Denmark,[4] 18% in Portugal,[4] 16% in Spain,[4] 14% in Ireland[8] and 9% in Germany in 2010.[4][9] As of 2011, 83 countries around the world are using wind power on a commercial basis.[9]
A large wind farm may consist of several hundred individual wind turbines which are connected to the electric power transmission network. Offshore wind power can harness the better wind speeds that are available offshore compared to on land, so offshore wind power’s contribution in terms of electricity supplied is higher.[10] Small onshore wind facilities are used to provide electricity to isolated locations and utility companies increasingly buy back surplus electricity produced by small domestic wind turbines. Although a variable source of power, the intermittency of wind seldom creates problems when using wind power to supply up to 20% of total electricity demand, but as the proportion rises, increased costs, a need to use storage such as pumped-storage hydroelectricity, upgrade the grid, or a lowered ability to supplant conventional production may occur.[11][12][13] Power management techniques such as excess capacity, storage, dispatchable backing supply (usually natural gas), exporting and importing power to neighboring areas or reducing demand when wind production is low, can mitigate these problems.
Wind power, as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean, produces no greenhouse gas emissions during operation, and uses little land. In operation, the overall cost per unit of energy produced is similar to the cost for new coal and natural gas installations.[14] The construction of wind farms is not universally welcomed, but any effects on the environment from wind power are generally much less problematic than those of any other power source.[15]
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