Wind power is the conversion of wind energy into a useful form of energy such as using wind turbines to make electricity windmills for mechanical power windpumps for water pumping or drainage or sails to propel ships. At the end of 2010 worldwide nameplate capacity of wind-powered generators was 197 gigawatts (GW). Energy production was 430 TWh which is about 2.5% of worldwide electricity usage; and has doubled in the past three years.