Wind is the movement of air from high-pressure areas to low-pressure areas. As the sun unevenly heats the surface of the Earth, hot air rises, and cold air sinks to fill in the space. This results in the difference in atmospheric pressure that generates wind. Accordingly, as long as the sun shines, the wind blows.

Wind has been a source of power for mankind before electricity became widely available. In ancient times, mariners raised sails to harness the wind, and farmers used windmills to grind grain and pump water. Today, more and more towering wind turbines are erected on land and at sea, spinning with the wind to generate electricity.

A wind turbine is comprised of the hub, wind vane, blades, nacelle, tower, and foundation. A wind turbine tower can be 60 stories high, and the diameter of a swept area can reach 160 meters long.

Wind turbines work on a simple principle. The wind spins three blades which in turn drive the generator to convert the kinetic energy of the wind into electrical energy; the wind vane directs the turbine to always face the windward side to capture the maximum wind power. Both onshore and offshore wind farms consist of many independent wind turbines which generate power that is first transmitted to the grid and eventually distributed to end-users.