Gran Canaria: Wind farm

A wind farm is a group of wind turbines 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 United States and China. For example, the Gansu Wind Farm in China has over 5,000 MW installed 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 1020 MW of power. As of Apr. 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), Anholt Offshore Wind Farm (400 MW), BARD Offshore 1 (400 MW), Clyde Wind Farm (350 MW), Lincs Wind Farm (270 MW), London Array (1000 MW), Lower Snake River Wind Project (343 MW), Macarthur Wind Farm (420 MW), Shepherds Flat Wind Farm (845 MW), and Sheringham Shoal (317 MW).

A wind turbine is a device that converts kinetic energy from the wind, also called wind energy, into mechanical energy; a process known as wind power. If the mechanical energy is used to produce electricity, the device may be called a wind turbine or wind power plant. If the mechanical energy is used to drive machinery, such as for grinding grain or pumping water, the device is called a windmill or wind pump. Similarly, it may be referred to as a wind charger when used for charging batteries.

The result of over a millennium of windmill development and modern engineering, today's wind turbines are manufactured in a wide range of vertical and horizontal axis types. The smallest turbines are used for applications such as battery charging or auxiliary power on boats; while large grid-connected arrays of turbines are becoming an increasingly important source of wind power-produced commercial electricity.

Wind power is the conversion of wind energy into a useful form of energy, such as using wind turbines to make electrical power, windmills for mechanical power, wind pumps for water pumping or drainage, or sails to propel ships.

Large wind farms consist of hundreds of individual wind turbines which are connected to the electric power transmission network. Offshore wind is steadier and stronger than on land, and offshore farms have less visual impact, but construction and maintenance costs are considerably higher. Small onshore wind farms provide electricity to isolated locations. Utility companies increasingly buy surplus electricity produced by small domestic wind turbines.

Wind power, as an alternative to fossil fuels, is plentiful, renewable, widely distributed, clean, produces no greenhouse gas emissions during operation and uses little land. The effects on the environment are generally less problematic than those from other power sources. As of 2011, Denmark is generating more than a quarter of its electricity from wind and 83 countries around the world are using wind power on a commercial basis. In 2010 wind energy production was over 2.5% of total worldwide electricity usage, and growing rapidly at more than 25% per annum. The monetary cost per unit of energy produced is similar to the cost for new coal and natural gas installations.

An intermittent energy source is any source of energy that is not continuously available due to some factor outside direct control. The intermittent source may be quite predictable, for example, tidal power, but cannot be dispatched to meet the demand of a power system. Effective use of intermittent sources in an electric power grid usually relies on using the intermittent sources to displace fuel that would otherwise be consumed by non-renewable power stations, or by storing energy in the form of renewable pumped storage, compressed air or ice, for use when needed, or as electrode heating for district heating schemes.

The storage of energy to fill the shortfall intermittency or for emergencies is part of a reliable energy supply. The capacity of a reliable renewable energy supply, can additionally be fulfilled by the use of latency measures and backup or extra infrastructure and technology, using mixed renewables to produce electricity above the intermittent average, which may be utilised to meet regular and unanticipated supply demands.

The penetration of intermittent renewables in most power grids is low, but wind generates circa 16% (EWEA - 2011 European Statistics, February 2012) of electric energy in Spain and Portugal, 9% in Ireland, and 7% in Germany. Wind provides nearly 20% of the electricity generated in Denmark; to operate with this level of penetration, Denmark exports surpluses and imports during shortfalls to and from the EU grid, particularly Norwegian Hydro, to balance supply with demand. It also uses^{[citation needed]} large numbers of combined heat and power (CHP) stations which can rapidly adjust output. The large thermal stores in these systems are also utilised to store surplus wind energy,^{[citation needed]} since thermal storage is the cheapest form of energy storage.