The principle is to use the wind to drive the windmill blades to rotate and then to increase the speed of rotation through a speed increaser to generate electricity from the generator. With current windmill technology, a breeze of around three metres per second is sufficient to start generating electricity. Wind power is becoming a worldwide craze because it does not require fuel and does not produce radiation or air pollution. The devices needed to generate electricity from wind power are called wind turbines. The wind turbine can be broadly divided into three parts: the wind turbine (including the rudder), the generator and the tower. (Large wind turbines basically do not have a rudder, only small ones, including domestic models, usually have a rudder)