Since wind speed increases with elevation above ground, wind turbines are installed on towers that are often as tall as a 20-storey building.
Wind power is generated by the force wind exerts on the blades of a turbine, causing the turbine's shaft to rotate at a speed of 10 to 20 revolutions per minute (rpm). The rotor shaft is connected to a generator that converts mechanical energy into electrical energy.
The amount of energy generated by a wind turbine depends on:
- wind speed (main factor)
- the area swept by the blades
- air density
Wind turbines require:
- a minimum wind speed (generally 12-14 km/h) to begin turning and generate electricity
- strong winds (50-60 km/h) to generate at full capacity
- winds of less than 90 km/h; beyond that speed, the turbines must be stopped to avoid damage