I think that horizontal blades can catch just as much wind as vertical ones, so the same mechanical energy.
I also see some advantages: the drop shadow is only a line, the noise will be a bit less because no blades come close, rotor should never be turned to the wind, birds will not fly through it and the top of the blades will not so high are not so far visible.
Answer
There are several types of windmills with horizontal blades. These fall under the heading Vertical Axis Wind Turbines (VAWT), or Vertical Axis Wind Turbines.
A simple example is the Savonius type. This winmill can easily be made with two half oil drums. This windmill is often used in developing countries to pump water. They are cheap and reliable, and rotate in any wind direction so aiming mechanisms are not required. Because the rotation is caused by the difference in resistance, the efficiency is not very great compared to other forms of wind turbines.
This brings us suddenly to the great advantage of the ‘classic’ turbine (the often seen windmill with 3 blades): it has the highest efficiency, and is therefore preferred.
Answered by
dr. ir. Nico Smets
Engineering Sciences
Avenue de la Plein 2 1050 Ixelles
http://www.vub.ac.be/
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