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A windfarm or wind park is a group of wind turbines in the same location used to produce electricity. A large wind farm may consist of several hundred individual wind turbines and cover an extended area of hundreds of square miles, but the land between the turbines may be used for agricultural or other purposes. A wind farm can also be located offshore. Many of the largest operational onshore wind farms are located in Germany, China and the United States. For example, the largest wind farm in the world, Gansu Wind Farm in China has a capacity of over 6,000 MW of power in 2012〔Watts, Jonathan & Huang, Cecily. (Winds Of Change Blow Through China As Spending On Renewable Energy Soars ), ''The Guardian'', 19 March 2012, revised on 20 March 2012. Retrieved 4 January 2012.〕 with a goal of 20,000 MW by 2020. The Alta Wind Energy Center in California, United States is the largest onshore wind farm outside of China, with a capacity of 1,020 MW.〔(Terra-Gen Press Release ), 17 April 2012〕 As of April 2013, the 630 MW London Array in the UK is the largest offshore wind farm in the world, followed by the 504 MW Greater Gabbard wind farm in the UK. There are many large wind farms under construction and these include Sinus Holding Wind Farm (700 MW), Lincs Wind Farm (270 MW), Lower Snake River Wind Project (343 MW), Macarthur Wind Farm (420 MW). == Design == As a general rule, economic wind generators require windspeed of 16 km/h (10 mph) or greater. An ideal location would have a near constant flow of non-turbulent wind throughout the year, with a minimum likelihood of sudden powerful bursts of wind. An important factor of turbine siting is also access to local demand or transmission capacity. Usually sites are screened on the basis of a wind atlas, and validated with wind measurements. Meteorological wind data alone is usually not sufficient for accurate siting of a large wind power project. Collection of site specific data for wind speed and direction is crucial to determining site potential〔(Wind energy-- the facts: a guide to the technology, economics and future of wind power ) page 32 ''EWEA'' 2009. Retrieved 13 March 2011.〕〔(【引用サイトリンク】title=WINData LLC - Wind energy engineering since 1991 )〕 in order to finance the project.〔(IEC61400-1 site assessment )〕 Local winds are often monitored for a year or more, and detailed wind maps constructed before wind generators are installed. The wind blows faster at higher altitudes because of the reduced influence of drag. The increase in velocity with altitude is most dramatic near the surface and is affected by topography, surface roughness, and upwind obstacles such as trees or buildings. Typically, the increase of wind speeds with increasing height follows a wind profile power law, which predicts that wind speed rises proportionally to the seventh root of altitude. Doubling the altitude of a turbine, then, increases the expected wind speeds by 10%, and the expected power by 34%. Individual turbines are interconnected with a medium voltage (usually 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 transmission system. Construction of a land-based wind farm requires installation of the collector system and substation, and possibly access roads to each turbine site. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wind farm」の詳細全文を読む スポンサード リンク
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