Using Wind Turbines in Urban Built-up Areas

Wind turbines generally don’t work well in built up areas, where they may be placed downwind from houses, tall hedgerows or trees.

An area might still be very windy, but this wind is made up of eddies and gusts with a lot of turbulence. Eddies come from various directions and the turbine cannot respond quickly enough to differing wind directions.

However, turbulence has an even more marked effect. A wind turbine doesn’t really work by wind pushing the blade around – most of the energy happens close to the blade tip which works on the basis of lift coming from areas of high and low pressure, similar to the wing of an aircraft. We all know what happens to the wing of an airplane when it hits turbulence. The same thing happens to the blade of a wind turbine, and the output of the turbine is decimated by this effect.

For this reason, a wind turbine must be as high as you can get it, and as far away from obstacles in the direction of prevailing winds. There are very few instances where a turbine can work effectively in a built up area, so unless you happen to be on the western edge of a housing estate, or have a site which is wide open to wind from anywhere between SW and NW, a turbine won’t work for you.

To assess the effects of obstacles, you should obtain a wind rose from the met office for your area, and estimate the percentage of wind you will lose due to obstacles located at different compass points from the turbine base.

David Cameron notoriously put a turbine on the roof of his house, and many people believed that this is a simple solution to our energy needs. It isn’t – rooftop turbines are the snake-oil of the domestic wind energy market. There are interesting efforts to make vertical axis machines that will work, but none of them are convincing as yet…