Wind is a vast potential source of renewable energy. Winds are generated by complex mechanisms involving the rotation of the Earth, the heat capacity of the Sun, the cooling effect of the oceans and polar ice caps, temperature gradients between land and sea, and the physical effects of mountains and other obstacles.
Wind energy is generated by converting wind currents into other forms of energy using wind turbines. Turbines extract energy from the passing air by converting kinetic energy from rotational movement via a rotor. The effectiveness of this conversion at any given site is commonly measured by its energy density or, alternatively, as a capacity factor. Wind energy is primarily used for electricity generation, both onsite and for transport to the grid. Wind energy is also used to pump bore water, particularly in rural areas.
The wind energy industry is the fastest growing renewable energy source in many countries and is expected to continue to grow rapidly over the period to 2030. Production of wind energy is largely concentrated in Europe and the United States. However, there has also been rapid growth in the wind energy industries in China and India.