Wind farm
A wind farm or wind park, also called a wind power station or wind power plant,[1] is a group of wind turbines in the same location used to produce electricity. Wind farms vary in size from a small number of turbines to several hundred wind turbines covering an extensive area. Wind farms can be either onshore or offshore.
Many of the largest operational onshore wind farms are located in China, India, and the United States. For example, the largest wind farm in the world, Gansu Wind Farm in China had a capacity of over 6,000 MW by 2012,[2] with a goal of 20,000 MW[3] by 2020.[4] As of December 2020, the 1218 MW Hornsea Wind Farm in the UK is the largest offshore wind farm in the world.[5] Individual wind turbine designs continue to increase in power, resulting in fewer turbines being needed for the same total output.
Because they require no fuel, wind farms have less impact on the environment than many other forms of power generation and are often referred to as a good source of green energy. Wind farms have, however, been criticised for their visual impact and impact on the landscape. Typically they need to be spread over more land than other power stations and need to be built in wild and rural areas, which can lead to "industrialization of the countryside", habitat loss, and a drop in tourism. Some critics claim that wind farms have adverse health effects, but most researchers consider these claims to be pseudoscience (see wind turbine syndrome). Wind farms can interfere with radar, although in most cases, according to the US Department of Energy, "siting and other mitigations have resolved conflicts and allowed wind projects to co-exist effectively with radar".[6]
Design[edit]
Turbine spacing[edit]
A major factor in wind-farm design is the spacing between the turbines, both laterally and axially (with respect to the prevailing winds). The closer the turbines are together, the more the upwind turbines block wind from their rear neighbors (wake effect). However, spacing turbines far apart increases the costs of roads and power cables, and raises the amount of land needed to install a specific capacity of turbines. As a result of these factors, turbine spacing varies by site. Generally speaking, manufacturers require a minimum of 3.5 times the turbine's rotor diameter of clear space between each adjacent turbine's respective spatial envelope.
Closer spacing is possible depending on the turbine model, the conditions at the site, and how the site will be operated. Airflows slow as they approach an obstacle, known as the 'blockage effect', reducing available wind power by 2% for the turbines in front of other turbines.[17][18]
Experimental and proposed wind farms[edit]
Experimental wind farms consisting of a single wind turbine for testing purposes have been built. One such installation is Østerild Wind Turbine Test Field.
Airborne wind farms have been envisaged. Such wind farms are a group of airborne wind energy systems located close to each other connected to the grid at the same point.[64]
Wind farms consisting of diverse wind turbines have been proposed in order to efficiently use wider ranges of wind speeds. Such wind farms are proposed to be projected under two criteria: maximization of the energy produced by the farm and minimization of its costs.[65]
Impact on agriculture[edit]
A 2010 study found that in the immediate vicinity of wind farms, the climate is cooler during the day and slightly warmer during the night than the surrounding areas due to the turbulence generated by the blades.[180]
In another study, an analysis carried out on corn and soybean crops in the central areas of the United States noted that the microclimate generated by wind turbines improves crops as it prevents the late spring and early autumn frosts, and also reduces the action of pathogenic fungi that grow on the leaves. Even at the height of summer heat, the lowering of 2.5–3 degrees above the crops due to turbulence caused by the blades can make a difference for the cultivation of corn.[181]