Vattenfall - The construction

The construction

The 30 turbines in the Kentish Flats project are identical and each wind turbine has a three-bladed rotor (blades and hub) positioned in the front of the nacelle (up-wind). The rotor is connected directly to the gear box in order to transfer the rotational energy to the generator, which transforms the wind energy into clean electricity. The wind turbines are designed for unmanned operation and will be remotely controlled and monitored around the clock throughout the year by a computer-based control system which will be placed at the operation and maintenance facility at Whitstable Harbour.

The energy in the wind

A wind turbine obtains its power input by converting the force of the wind into a torque (turning force) acting on the rotor blades. The amount of energy which the wind transfers to the rotor depends on the density of the air, the rotor area, and the wind speed. The energy of the rotor is converted into electric energy by the generator. The following example illustrates how much power the wind actually contains. The Kentish Flats wind turbine has a blade radius of 45 m which gives a swept area of 6,362 m2. At a wind speed of 8.7 m/s, which is the average wind speed at hub height on the site, a total volume of 6,362 m2 * 8.7 m/s = 55,349 m3/s of air is passing through the rotor every second. At a temperature of 15 o Celsius 1 m3 of air weighs approx 1.225 kg. The total weight of the air passing the rotor of the wind turbines each second is therefore:
6,362 m2 * 8.7 m/s * 1.225 kg/m3 = 71,256 kg/s. That is more than 71 tonnes per second.

1. Blade
2. Hub
3. Spinner
4. Gearbox
5. Generator
6. Controler
7. Yaw bearing