Wind power

Airflows can be used to run wind turbines. Modern wind turbines range from around 600kW to up to 5 MW of rated power, although turbines with rated output of 1.5-3 MW have become the most common for commercial use. The power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically. Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms.

Wind power is the fastest growing of the renewable energy technologies, though it currently provides less than 0.5% of global energy. Over the past decade, global installed maximum capacity increased from 2,500 MW in 1992 to just over 40,000 MW at the end of 2003, at an annual growth rate of near 30%. Due to the intermittency of wind resources, most deployed turbines in the EU produce electricity an average of 25% of the hours in a year (a capacity factor of 25%), but under favourable wind regimes some reach 35% or higher. Capacity factors are a function of seasonal wind fluctuations and may be higher in winter. It would mean that a typical 5 MW turbine in the EU would have an average output of 1.7 MW.

Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand. This could require large amounts of land to be utilized for wind turbines, particularly in areas of higher wind resources. Offshore resources experience mean wind speeds of ~90% greater than that of land, so offshore resources could contribute substantially more energy. This number could also increase with higher altitude ground-based or airborne wind turbines.

Wind strengths near the Earth's surface vary and thus cannot guarantee continuous power unless combined with other energy sources or storage systems. Some estimates suggest that 1,000 MW of conventional wind generation capacity can be relied on for just 333 MW of continuous power. While this might change as technology evolves, advocates have suggested incorporating wind power with other power sources, or the use of energy storage techniques, with this in mind. It is best used in the context of a system that has significant reserve capacity such as hydro, or reserve load, such as a desalination plant, to mitigate the economic effects of resource variability.

Wind power is renewable and produces no greenhouse gases during operation, such as carbon dioxide and methane.