Wind power

Wind power

A wind turbine.
Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electricity, wind mills for mechanical power, wind pumps for pumping water or drainage, or sails to propel ships.
At the end of 2009, worldwide nameplate capacity of wind-powered generators was 159.2 gigawatts (GW).[1] Energy production was 340 TWh, whichis about 2% of worldwide electricity usage;[1][2] and is growing rapidly, having doubled in the past three years. Several countries have achieved relatively high levels of wind power penetration (with large governmental subsidies), such as 20% of stationary electricity production in Denmark, 14% in Portugal and Spain, 11% in Republic of Ireland, and 8% in Germany in 2009.[3] As of May 2009, 80countries around the world are using wind power on a commercial basis.[2]
Large-scale wind farms are connected to the electric power transmission network; smaller facilities are used to provide electricity to isolated locations. Utility companies increasingly buy back surplus electricity produced by small domestic turbines. Wind energy, as an alternative to fossil fuels, is plentiful, renewable,widely distributed, clean, and produces no greenhouse gas emissions during operation. However, the construction of wind farms is not universally welcomed because of their visual impact and other effects on the environment.
Wind power is non-dispatchable, meaning that for economic operation, all of the available output must be taken when it is available. Other resources, such as hydropower, and loadmanagement techniques must be used to match supply with demand. The intermittency of wind seldom creates problems when using wind power to supply a low proportion of total demand, but costs rise as does the proportion.[4][5]
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History

Medieval depictionof a windmill

Windmills are typically installed in favourable windy locations. In the image, wind power generators in Spain near an Osborne bull
Humans have been using wind power for at least 5,500 years to propel sailboats and sailing ships, and architects have used wind-driven natural ventilation in buildings since similarly ancient times. Windmills have been used for irrigation pumping andfor milling grain since the 7th century AD in what is now Afghanistan, Iran and Pakistan.
In the United States, 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. Windpumps contributed to the expansion of rail transport systems throughout the world, by pumping water from water wellsfor the steam locomotives.[6] The multi-bladed wind turbine atop a lattice tower made of wood or steel was, for many years, a fixture of the landscape throughout rural America. When fitted with generators and battery banks, small wind machines provided electricity to isolated farms.
In July 1887, a Scottish academic, Professor James Blyth, undertook wind power experiments that culminated in a UKpatent in 1891.[7] In the United States, Charles F. Brush produced electricity using a wind powered machine, starting in the winter of 1887-1888, 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 then used to produce hydrogen.[7] These were the first of what was to becomethe modern form of wind turbine.
Small wind turbines for lighting of isolated rural buildings were widespread in the first part of the 20th century. Larger units intended for connection to a distribution network were tried at several locations including Balaklava USSR in 1931 and in a 1.25 megawatt (MW) experimental unit in Vermont in 1941.
The modern wind power industry began in 1979 with the...