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Wind farm

Wind farm

Overview
A wind farm is a group of wind turbine
Wind turbine
A wind turbine is a device that converts kinetic energy from the wind into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or...

s in the same location used to produce electric power. 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 may also be located offshore.

Many of the largest operational onshore wind farms are located in the USA.
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Encyclopedia
A wind farm is a group of wind turbine
Wind turbine
A wind turbine is a device that converts kinetic energy from the wind into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or...

s in the same location used to produce electric power. 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 may also be located offshore.

Many of the largest operational onshore wind farms are located in the USA. As of November 2010, the Roscoe Wind Farm
Roscoe Wind Farm
The Roscoe Wind Farm in Roscoe, Texas, owned and operated by E.ON Climate & Renewables is the world's largest capacity wind farm with 627 wind turbines and a total installed capacity of 781.5 MW, which surpasses the nearby 735.5 MW Horse Hollow Wind Energy Center.Roscoe was constructed in four phases...

 is the largest onshore wind farm in the world, producing 781.5 MW of power, followed by the Horse Hollow Wind Energy Center
Horse Hollow Wind Energy Center
Horse Hollow Wind Energy Center is a large wind farm with 735.5 megawatt capacity. It consists of 291 GE 1.5 MW wind turbines and 130 Siemens 2.3 MW wind turbines spread over nearly 47,000 acres of land in Taylor and Nolan County, Texas....

 (735.5 MW). As of November 2010, the Thanet Offshore Wind Project
Thanet Offshore Wind Project
The Thanet Wind Farm is an offshore wind farm off the coast of Thanet district in Kent, England. As of September 2010, it is the world's biggest offshore windfarm. It has a nameplate capacity of 300 MW and it cost £780-900 million...

 in United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 is the largest offshore wind farm in the world at 300 MW, followed by Horns Rev II
Horns Rev 2
Horns Rev 2 is an offshore wind farm located on Horns Rev in a shallow area in the eastern North Sea, about off the westernmost point of Denmark, Blåvands Huk...

 (209 MW) in Denmark.

There are many large wind farms under construction and these include BARD Offshore 1
BARD Offshore 1
BARD Offshore 1 is a 400 megawatt North Sea offshore wind farm that is presently under construction and is expected to be fully operational by 2012. It will be an 80-turbine wind farm, located northwest of the isle Borkum, in Germany, in water which is deep.Laying of cables to connect the...

 (400 MW), Clyde Wind Farm
Clyde Wind Farm
The Clyde Wind Farm is a 548 megawatt wind farm under construction near Abington in South Lanarkshire, Scotland. When completed, it will be Europe's largest onshore wind farm...

 (548 MW), Greater Gabbard wind farm (500 MW), Lincs Wind Farm
Lincs Wind Farm
The Lincs Wind Farm is a wind farm currently under construction off Skegness on the east coast of England. Construction of the 270 megawatt project began in 2010 using 75 3.6 MW Siemens Wind Power‎ wind turbines. The project, due to be operational in 2012, will cost £725 million ...

 (270 MW), London Array
London Array
The London Array is an offshore wind farm under construction in the outer Thames Estuary in the United Kingdom. With 1,000 megawatt capacity, it is expected to become the world's largest offshore wind farm. The site is off the North Foreland on the Kent coast in the area of Long Sand and...

 (1000 MW), Lower Snake River Wind Project
Lower Snake River Wind Project
The Lower Snake River Wind Project is under construction in Washington’s Garfield and Columbia counties. The wind farm is being developed in phases with the first phase consisting of 149 Siemens wind turbines rated at 2.3 MW each for a maximum generating capacity of 343 MW...

 (343 MW), Macarthur Wind Farm
Macarthur Wind Farm
The Macarthur Wind Farm is a wind farm under construction in Victoria, Australia, being built by a joint venture formed by AGL Energy and Meridian Energy. The project is located in Macarthur, Victoria on a 5,500 ha site and it has been permitted to generate up to 420 MW. The wind farm will...

 (420 MW), Shepherds Flat Wind Farm
Shepherds Flat Wind Farm
The Shepherds Flat Wind Farm is an 845 megawatt wind farm under construction in Oregon, United States. The project is located in Eastern Oregon in both Morrow and Gilliam counties, near Arlington. Approved in 2008 by state regulators, groundbreaking came in 2009...

 (845 MW), Sheringham Shoal
Sheringham Shoal Offshore Wind Farm
Sheringham Shoal Offshore Wind Farm is an offshore wind farm under construction in the United Kingdom by Scira, owned by Statoil and Statkraft with 50% each. Scira has leased the area from The Crown Estate for 40 years. The first turbine was connected to the grid in August 2011. The nearest turbine...

 (317 MW), and the Walney Wind Farm
Walney Wind Farm
Walney Wind Farm is an offshore wind farm currently under construction 14km west of Walney Island off the coast of Cumbria, in the Irish Sea, England. It is being developed by Walney Offshore Windfarms Limited, a partnership between Dong Energy and Scottish and Southern Energy. The farm is...

 (367 MW).

Design


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 may be located offshore to take advantage of strong winds blowing over the surface of an ocean or lake.


As a general rule, economic wind generators require windspeed of 10 mph (16 km/h) 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
Electric power transmission
Electric-power transmission is the bulk transfer of electrical energy, from generating power plants to Electrical substations located near demand centers...

 capacity.

Usually sites are screened on the basis of a wind atlas
Wind atlas
A wind atlas contains data on the wind speed and wind direction in a region. These data include maps, but also time series or frequency distributions. A climatological wind atlas covers hourly averages at a standard height over even longer periods...

, and validated with wind measurements. Meteorological
Meteorology
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

 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 in order to finance the project. 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
Wind profile power law
The wind profile power law is a relationship between the wind speeds at one height, and those at another.The power law is often used in wind power assessments where wind speeds at the height of a turbine must be estimated from near surface wind observations , or where wind speed data at various...

, 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
Electrical substation
A substation is a part of an electrical generation, transmission, and distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions...

, this medium-voltage electrical current is increased in voltage with a transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...

 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.

Onshore installations



The world's first wind farm – consisting of 20 wind turbines rated at 30 kilowatts each – was installed on the shoulder of Crotched Mountain in southern New Hampshire
New Hampshire
New Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...

 in December, 1980.

Many of the largest operational onshore wind farms are located in the USA. As of November 2010, the Roscoe Wind Farm
Roscoe Wind Farm
The Roscoe Wind Farm in Roscoe, Texas, owned and operated by E.ON Climate & Renewables is the world's largest capacity wind farm with 627 wind turbines and a total installed capacity of 781.5 MW, which surpasses the nearby 735.5 MW Horse Hollow Wind Energy Center.Roscoe was constructed in four phases...

 is the largest onshore wind farm in the world at 781.5 MW, followed by the Horse Hollow Wind Energy Center
Horse Hollow Wind Energy Center
Horse Hollow Wind Energy Center is a large wind farm with 735.5 megawatt capacity. It consists of 291 GE 1.5 MW wind turbines and 130 Siemens 2.3 MW wind turbines spread over nearly 47,000 acres of land in Taylor and Nolan County, Texas....

 (735.5 MW). The largest wind farms under construction are the 845 MW Shepherds Flat Wind Farm
Shepherds Flat Wind Farm
The Shepherds Flat Wind Farm is an 845 megawatt wind farm under construction in Oregon, United States. The project is located in Eastern Oregon in both Morrow and Gilliam counties, near Arlington. Approved in 2008 by state regulators, groundbreaking came in 2009...

 and the 800 MW Alta Wind Energy Center
Alta Wind Energy Center
The Alta Wind Energy Center is a wind farm located in Tehachapi Pass of the Tehachapi Mountains, in Kern County, California. As of 2011, it is the largest wind farm in California, with a combined installed capacity of 720 MW. The project, which is being developed near Tehachapi Pass Wind Farm...

 in the USA. The largest proposed project is the 20,000 MW Gansu Wind Farm
Gansu Wind Farm
The Gansu Wind Farm is a group of large wind farms under construction in western Gansu province in China , , . The project is one of six national wind power megaprojects approved by the Chinese government. It is expected to grow to 20,000 megawatts by 2020, at an estimated cost of 120 billion...

 in China.

Falling costs mean that the average onshore wind farm will be competitive with natural gas-fired power generation by 2016.
World's largest onshore wind farms
Wind farm Current
capacity
(MW)
Country Notes
Altamont Pass Wind Farm
Altamont Pass Wind Farm
The Altamont Pass Wind Farm is located in the Altamont Pass of the Diablo Range in Central California. It is one of the earliest wind farms in the United States. The wind farm is composed of 4930 relatively small wind turbines of various types, making it at one time the largest farm in the world in...

 
606 USA
Biglow Canyon Wind Farm
Biglow Canyon Wind Farm
Biglow Canyon Wind Farm is an electricity generating wind farm facility in Sherman County, Oregon, United States. It is owned by Portland, Oregon, based Portland General Electric and began operations in 2007. With the completion of phase 3 of the project it has a generating capacity of 450 megawatts...

 
450 USA
Buffalo Gap Wind Farm
Buffalo Gap Wind Farm
The Buffalo Gap Wind Farm is located in Nolan and Taylor Counties, about south west of Abilene, Texas. It was constructed in three phases and has a total wind generation capacity of 524 megawatts ....

 
523.3 USA
Capricorn Ridge Wind Farm
Capricorn Ridge Wind Farm
The Capricorn Ridge Wind Farm is located in Sterling and Coke counties, Texas. It is a 662.5 MW wind farm, with 342 GE 1.5 MW wind turbines and 65 2.3 MW Siemens turbines that are capable of generating enough electricity for more than 220,000 homes...

 
662.5 USA
Dabancheng Wind Farm  500 China
Fowler Ridge Wind Farm
Fowler Ridge Wind Farm
The Fowler Ridge Wind Farm currently consists of two completed phases with the possibility of a third phase some time in the near future. The wind farm is in Benton County, Indiana, near the city of Fowler, IN about northwest of Lafayette and northwest of Indianapolis...

 
599.8 USA
Horse Hollow Wind Energy Center
Horse Hollow Wind Energy Center
Horse Hollow Wind Energy Center is a large wind farm with 735.5 megawatt capacity. It consists of 291 GE 1.5 MW wind turbines and 130 Siemens 2.3 MW wind turbines spread over nearly 47,000 acres of land in Taylor and Nolan County, Texas....

 
735.5 USA
Meadow Lake Wind Farm
Meadow Lake Wind Farm
Meadow Lake Wind Farm is a wind farm near Brookston and Chalmers, Indiana, spreading over portions of White, Jasper, and Benton Counties in Indiana, owned and operated by Horizon Wind Energy...

 
500 USA
Panther Creek Wind Farm
Panther Creek Wind Farm
The Panther Creek Wind Farm in Big Spring, Texas, USA consists of 305 wind turbines and has an installed capacity of 457.5 megawatts, making it one of the ten largest wind farms in the United States. Phases I and II of the wind farm became operational early in 2009, with the completion of the...

 
458 USA AWEA: U.S. Wind Energy Projects - Texas
Roscoe Wind Farm
Roscoe Wind Farm
The Roscoe Wind Farm in Roscoe, Texas, owned and operated by E.ON Climate & Renewables is the world's largest capacity wind farm with 627 wind turbines and a total installed capacity of 781.5 MW, which surpasses the nearby 735.5 MW Horse Hollow Wind Energy Center.Roscoe was constructed in four phases...

 
781.5 USA
San Gorgonio Pass Wind Farm
San Gorgonio Pass Wind Farm
The San Gorgonio Pass Wind Farm is a wind farm located on the eastern slope of the San Gorgonio Pass in Riverside County, just east of White Water, California, United States. Developed beginning in the 1980s, it is one of three major wind farms in California, along with those at Altamont and the...

 
619 USA
Sweetwater Wind Farm
Sweetwater Wind Farm
Sweetwater Wind Farm is one of the largest wind farms in Texas. Construction of the 585 MW wind farm has proceeded in five stages, and some generating capacity is still being built....

 
585.3 USA
Tehachapi Pass Wind Farm
Tehachapi Pass Wind Farm
Wind development in the Tehachapi Pass began in the early 1980s. The area hosts a multitude of wind farms, comprising one of California's largest wind resource areas. The pass is undergoing much repowering activity...

690 USA