This article is about wind-powered electrical generators. For wind-powered machinery used to grind grain or turbine efficiency calculation pdf water, see Windmill and Windpump.
Offshore wind farm, using 5 MW turbines REpower 5M in the North Sea off the coast of Belgium. A wind turbine is a device that converts the wind’s kinetic energy into electrical energy. 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 for auxiliary power for boats or caravans or to power traffic warning signs.
Slightly larger turbines can be used for making contributions to a domestic power supply while selling unused power back to the utility supplier via the electrical grid. Arrays of large turbines, known as wind farms, are becoming an increasingly important source of intermittent renewable energy and are used by many countries as part of a strategy to reduce their reliance on fossil fuels.
The windwheel of Hero of Alexandria marks one of the first recorded instances of wind powering a machine in history. However, the first known practical wind power plants were built in Sistan, an Eastern province of Iran, from the 7th century. These “Panemone” were vertical axle windmills, which had long vertical drive shafts with rectangular blades. Made of six to twelve sails covered in reed matting or cloth material, these windmills were used to grind grain or draw up water, and were used in the gristmilling and sugarcane industries.