Surveying site suitability

A suitable site needs enough wind.

As a rough guide wind power generation becomes viable at an average wind speed of 5 m/s . ( 1 metre /sec = 2.24 miles/hour) . Wind speed increases with height above ground. Calculated values for average wind speed at various heights are available for the whole of the UK. The map below shows the average wind speed in the south west at a height of 10m. The red colour indicates average wind speed of 5 m/s and above. Data was obtained from the DTI wind speed database.

devonmap

The wind speed database gives the average annual wind speed over an area 1km square and can therefore only be a rough guide to the actual value at any particular location, nevertheless it is a good starting point. Looking at the typical weather conditions you experience at the site will also give a good indication of the wind resource. The Beaufort wind scale is very helpful here

beaufort

A site with an average wind speed of 5m/s will experience a wide variety of wind speeds from dead calm to gale force. The range 3 to 6 on the Beaufort Scale will see most wind turbines start producing electric power at the lower end and limit output power and speed of rotation at the higher end. A doubling of wind speed leads to an eightfold increase in power.