Wind Turbines

Windmills were used for 100s of years in Norfolk to power mills and pumps. Modern windmills, called turbines, use knowledge from aircraft engine design to produce electricity.

Turbines come in all sizes, from ones to fit on the roof, to 5 MW freestanding ones, some examples in the table below.

Domestic scale, connected to household meter. planning easier, made in UK

Large turbines – connected through grid, full planning restrictions, made overseas
Type of turbinesOutputHub heightDiameterHeightCost
Proven 73.2kW6.5m – 11m3.5m8.25-12.75m£12,096
Proven 116kW9m -15m5.5m11.75 – 17.75m£19.647
Proven 3515kW15m9m19.5m£44,886
Segen Gaia133116kW18m6.2m24.5m£45-50,000
Enercon 822MW78m82m119m€2.6 - 2.9 million
Vestas 903MW80m90m125m£1 million +
Repower5MW120m126m193m£1 million +

(Enercon turbines are the most expensive, but are quiet and very reliable.)

Large Turbines in Norfolk:

PlaceOutputTower HeightBlade DiameterTotal HeightDate installed
Swaffham1 - 1.5MW67m66m100m1999
Martham1.5 MW65m70m100m2000
Swaffham 21.8 MW85m70m120m2003
Ness point2.75MW80m92m126m2005
Hemsby2.5 MW60m90m105mproposed
Kessingland3.0 MW80m90m125magreed
Recent advances have increased productivity. Some of this has been an increase in size. But note there is not much difference between the total height of 1.5MW Enercon turbine at Swaffham and the 2.5MW turbine proposed at Hemsby, nor between 2MW Enercon 82, and 3MW Vestas 90.

Increased size maximises output and profits

A higher tower means better wind speeds, less turbulence from the ground.

Larger blades produce a logarithmic increase in electricity.

The disadvantages of size - More visual intrusion; possibly more expensive grid connection; difficulties in transporting the turbine to the site; can lead to larger initial costs.

There have been many other engineering developments to reduce weight and noise, increase reliability and develop turbines to operate in lower wind speeds.

*Output - The MW rating means the turbines can produce that electricity in an hour, when operating at full capacity. On a good site this will be about 30% - 25% of the time.

A 1MW turbine will produce enough electricity to supply about 900 people.

1 kilowatt (kW) = 1000 watts; 1 megawatt (MW) = 1000kWs; 1gigawatt (GW) = 1000MWs

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