One of the features of a vertical axis turbine is that it does not need to orientate itself into the wind like a horizontal turbine. This feature of the horizontal turbine is know as yaw. Vertical turbines are therefore potentially simpler in design with less moving parts, less to go wrong and less to wear out.

Vertical axis turbines come in two different types. There are lift turbines and drag turbines. Both have their advantages and disadvantages.

George Darrius invented the lift turbine which is sometimes also called a Darrius turbine. The rotating blades are shaped like an airplanes wing which is designed to create lift to get the plane airborne. In the same way the wind blowing across the aerofoil blade causes the blade to rotate faster. This contrasts with the drag turbine blade which is just dragged around and around by the wind. This means that the rotor blades in a 2 KW turbine can be smaller in a lift turbine and yet generate the same power as a larger drag turbine. However, there is just one small but very significant problem. The faster the blades go the noisier they get.

The drag turbine as we have discussed is not as efficient as the lift turbine, but it does have a number of advantages. It is self starting. This means that the design can be simpler. It also runs more slowly. This means it is less noisy. Overall drag turbines have been available for longer than the lift turbine and have a good track record of operation in the real world.

Wind power has been the poor relation of alternative power generation for the domestic market, which has tended to focus on solar power. The irony is that wind power can be more cost effective than solar providing the conditions are right. In order to consider wind power you will need an average speed of at least 5 meters per second or 11 miles per hour. The other important factor is turbulence. As the wind strikes building and trees turbulence is created. For efficient operation turbines need a nice clean wind.