The energy of motion is known as "kinetic energy". Wind turbines work by turning the kinetic energy in the wind into electricity.
The nacelle is located at the top of the tower and houses the mechanical machinery such as the generator and gearbox.
The rotor transforms the energy from the wind into rotational energy. Most modern wind turbine rotors consist of three turbine blades attached to a hub, although two bladed and one bladed turbines can also be found. Modern commercial wind turbine blades range from 30 to 70 metres in length and are generally made of glass-fibre reinforced polyester or wood-epoxy. A modern commercial wind turbine rotor is likely to have a rotational speed of between 15 to 30 rpm.
Low-speed shaft
The rotor turns the low-speed shaft rotates at between 15 to 30 rpm.
The gearbox increases the rotational speed of the low speed shaft (15 to 30 rpm) and delivers it to the high speed shaft (1000 – 3000 rpm) which drives the generator. Some modern wind turbines have a ‘direct drive’ generator instead of a gearbox.
High-speed shaft
Drives the generator and rotates at between 1000 and 3000 rpm.
The generator uses magnetic fields to convert the resultant rotational energy into electrical energy.
The anemometer and wind vane are both located on the back of the nacelle and monitor wind direction and wind speed. The information gathered is used by the wind turbine control systems to ensure that the wind turbine is facing into the wind and generating the maximum amount of energy. The wind speed data is also used to monitor performance and let the operating system know when to start and shut down the turbine. A modern wind turbine starts generating energy at wind speeds of about 4 to 5 m/s (9 to 11 mph) and shuts down at about 25 m/s (56 mph).
The yaw mechanism turns the nacelle and rotor towards the prevailing wind
Tower: Most modern turbines are made out of tubular steel although lattice towers are still used in some countries. Towers for modern commercial turbines range in height from 60 metres to 100 metres.
The transformer converts voltage to that required for the electricity network. The transformer can be within the tower or located outside at the base of the tower.
For further information on how a wind turbine works you can view the relevant sections from the British Wind Energy Association (BWEA), the Danish Wind Industry Association or the US Department of Energy. Alternatively you can view the Companion Guide to Planning Policy Statement 22 (page 155 to 165) produced by the Office of the Deputy Prime Minister.