The High Winds Community Energy Society have built two new high powered turbines on the Harlock Hill site, which was formally home to Baywinds turbines. The turbines are now generating electricity and feeding into the national grid.
The New Turbines at Harlock Hill
The Enercon E70 turbines are German built by Enercon and are (each) rated at 2.3MW. The E70 is a popular machine and is especially useful at sites with high wind speeds. The rotor is three bladed and each fibreglass blade rotates clockwise. The length of the blade is 35.5m, the hub height is 64.0m making the height from ground to tip 99.5m. The rotor turns in the speed range 6.0-21.5 rpm and the rated power is produced at wind speeds of 15m/s (the equivalent of 33mph) and above. At wind speeds above 25m/s the machine will shut down to avoid over stressing the components and will automatically resume once the wind speed drops to 20m/s.
The blade profile is like that of an aircraft wing and the pitch-the angle of attack to the wind- is variable according to the wind speed. The tips of the blades are turned up (like a modern aircraft wing) and reduce the air turbulence at the tip resulting in less noise.
There is a control system to achieve maximum output under all weather conditions. The turbine has yaw control, that is, internal machinery moves the rotor to face the wind direction according to an anemometer on the nacelle.
There is no gear-box: the rotating rotor shaft passes through the centre of an annular generator. This means that there is no noise produced compared with the arrangement with an intermediate gearbox, that there are few rotating components leading to reduced mechanical stress, operating and maintenance costs.
