Ever Heard about Wind Farm ?

A wind farm or wind park, also called a wind power station or wind power plant, 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 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 September 2018, the 659 MW Walney 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.

Wind farms tend to have much less impact on the environment than many other power stations. Onshore wind farms are also criticized for their visual impact and impact on the landscape, as typically they need to take up 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. Critics have linked wind farms to adverse health effects (see wind turbine syndrome). Wind farms have also been criticized for interfering with radar, radio and television reception

Design and location

Map of available wind power over the United States. Color codes indicate wind power density class

The location is critical to the success of a wind farm. Conditions contributing to a successful wind farm location include: wind conditions, access to electric transmission, physical access, and local electric prices.

The faster the average wind speed, the more electricity the wind turbine will generate, so faster winds are generally economically better for wind farm developments. The balancing factor is that strong gusts and high turbulence require stronger more expensive turbines, otherwise they risk damage. The average power in the wind is not proportional to the average wind speed, however. For this reason, the ideal wind conditions would be strong but consistent winds with low turbulence coming from a single direction.

Mountain passes are ideal locations for wind farms under these conditions. Mountain passes channel wind blocked by mountains through a tunnel like pass towards areas of lower pressure and flatter land.^[7] Passes used for wind farms like the San Gorgonio Pass and Altamont Pass are known for their abundant wind resource capacity and capability for large-scale wind farms. These types of passes were the first places in the 1980’s to have heavily invested large-scale wind farms after approval for wind energy development by the U.S. Bureau of Land Management. From these wind farms, developers learned a lot about turbulence and crowding effects of large-scale wind projects previously unresearched in the U.S. due to the lack of operational wind farms large enough to conduct these types of studies on.^[8]

Usually sites are screened on the basis of a wind atlas, and validated with on-site wind measurements via long term or permanent meterological-tower data using anemometers and wind vanes. 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^[9][10] in order to finance the project.^[11] Local winds are often monitored for a year or more, detailed wind maps are constructed, along with rigorous grid capability studies conducted, before any wind generators are installed.

Part of the Biglow Canyon Wind Farm, Oregon, United States with a turbine under construction

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. However, at higher altitudes, the power in the wind decreases proportional to the decrease in air density. Rendering significantly less efficient power extraction by the wind turbines, requiring for a higher investment for the same generation capacity at lower altitudes.^[12]

How closely to space the turbines together is a major factor in wind farm design. The closer the turbines are together the more the upwind turbines block wind from their neighbors. However spacing turbines far apart increases the costs of roads and 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 3.5 times the rotor diameter of the turbine between turbines as a minimum. Closer spacing is possible depending on the turbine model, the conditions at the site, and how the site will be operated.^{[citation needed]}

Often in heavily saturated energy markets, the first step in site selection  for large-scale wind projects before wind resource data collection is finding areas with adequate Available Transfer Capability (ATC). ATC is the measure of the remaining capacity in a transmission system available for further integration of generation without significant upgrades to transmission lines and substations, which have substantial costs, potentially undermining the viability of a project within that area, regardless of wind resource availability.^[13] Once a list of capable areas is constructed, the list is refined based on long term wind measurements, among other environmental or technical limiting factors such as proximity to load and land procurement.

Many Independent System Operators (ISO’s) in the United States such as the California ISO and Midcontinent ISO use interconnection request queues to allow developers to propose new generation for a specific given area and grid interconnection.^[14] These request queues have both deposit costs at the time of request and ongoing costs for the studies the ISO will make for up to years after the request was submitted to ascertain the viability of the interconnection due to factors such as ATC.^[15] Larger corporations who can afford to bid the most queues will most likely have market power as to which sites with the most resource and opportunity get to be developed upon. After the deadline to request a place in the queue has passed, many firms will withdraw their requests after gauging the competition in order to make back some of the deposit for each request that is determined too risky in comparison to other larger firms’ requests.

Onshore turbine installations in hilly or mountainous regions tend to be on ridges generally three kilometres or more inland from the nearest shoreline. This is done to exploit the topographic acceleration as the wind accelerates over a ridge. The additional wind speeds gained in this way can increase energy produced because more wind goes through the turbines. The exact position of each turbine matters, because a difference of 30m could potentially double output. This careful placement is referred to as 'micro-siting'.

Europe is the leader in offshore wind energy, with the first offshore wind farm (Vindeby) being installed in Denmark in 1991. As of 2010, there are 39 offshore wind farms in waters off Belgium, Denmark, Finland, Germany, Ireland, the Netherlands, Norway, Sweden and the United Kingdom, with a combined operating capacity of 2,396 MW. More than 100 GW (or 100,000 MW) of offshore projects are proposed or under development in Europe. The European Wind Energy Associationhas set a target of 40 GW installed by 2020 and 150 GW by 2030

Offshore wind turbines are less obtrusive than turbines on land, as their apparent size and noise is mitigated by distance. Because water has less surface roughness than land (especially deeper water), the average wind speed is usually considerably higher over open water. Capacity factors (utilisation rates) are considerably higher than for onshore locations.^[53]

The province of Ontario in Canada is pursuing several proposed locations in the Great Lakes, including the suspended^[54] Trillium Power Wind 1 approximately 20 km from shore and over 400 MW in size.^[55] Other Canadian projects include one on the Pacific west coast.^[56]

In 2010, there were no offshore wind farms in the United States, but projects were under development in wind-rich areas of the East Coast, Great Lakes, and Pacific coast;^[31] and in late 2016 the Block Island Wind Farm was commissioned.

Installation and service / maintenance of off-shore wind farms are a specific challenge for technology and economic operation of a wind farm. As of 2015, there are 20 jackup vesselsfor lifting components, but few can lift sizes above 5MW.^[57] Service vessels have to be operated nearly 24/7 (availability higher than 80% of time) to get sufficient amortisation from the wind turbines.^{[citation needed]} Therefore, special fast service vehicles for installation (like Wind Turbine Shuttle) as well as for maintenance (including heave compensation and heave compensated working platforms to allow the service staff to enter the wind turbine also at difficult weather conditions) are required. So-called inertial and optical based Ship Stabilization and Motion Control systems (iSSMC) are used for that.