Wind power is the conversion of wind
energy into a useful form of energy, such as using wind turbines to
make electricity (wind power plant), wind mills for mechanical power,
wind pumps for pumping water or drainage, or sails to propel ships.
At the end of 2009, worldwide
nameplate capacity of wind-powered generators (wind power
plant) was 159.2 gigawatts (GW). Energy production from wind power
plant was 340 TWh, which is about 2% of worldwide electricity usage;
and is growing rapidly, having doubled in the past three years. Several
countries have achieved relatively high levels of wind power penetration (with
large governmental subsidies), such as 19% of stationary electricity production
in Denmark, 13% in Spain and Portugal, and 7% in Germany and the Republic of
Ireland in 2008. As of May 2009, eighty countries around the world are
using wind power on a commercial basis.
Large-scale wind
farms are connected to the electric power transmission network;
smaller facilities are used to provide electricity to isolated locations.
Utility companies increasingly buy back surplus electricity produced by small
domestic turbines. Wind energy as a power source is attractive as an
alternative to fossil fuels, because it is plentiful, renewable energy,
widely distributed, clean, and produces no greenhouse gas emissions. However,
the construction of wind farms is not universally welcomed because of their
visual impact and other effects on the environment.
Wind power is non-dispatchable, meaning that
for economic operation, all of the available output must be taken when it is
available. Other resources, such as hydropower, and standard load management
techniques must be used to match supply with demand. The intermittency of wind
seldom creates problems when using wind power to supply a low proportion of
total demand, but costs rise as does the proportion.