Young Curly Blonde Girl Wearing A Headband In The Wind Farm With Wind Turbines

When a turbine is mounted on a rooftop, the building generally redirects wind over the roof and this can double the wind speed at the turbine. If the height of the rooftop mounted turbine tower is approximately 50% of the building height, this is near the optimum for maximum wind energy and minimum wind turbulence. It should be borne in mind that wind speeds within the built environment are generally much lower than at exposed rural sites.
Another type of vertical axis is the Parallel turbine similar to the crossflow fan or centrifugal fan it uses the ground effect. Vertical axis turbines of this type have been tried for many years: a large unit producing up to 10 kW was built by Israeli wind pioneer Bruce Brill in 1980s: the device is mentioned in Dr. Moshe Dan Hirsch's 1990 report, which decided the Israeli energy department investments and support in the next 20 years. The Magenn WindKite blimp uses this configuration as well, chosen because of the ease of running.
Subtypes of the vertical axis design include: