The shortcomings of the older versions of these concepts stem from "pulsatory torque", whichcauses damaging bending of the rotor blades. VAWTs also tend put undue strain on the bearings.
Pros and cons of vertical-axis wind turbines
Traditional vertical-axis wind turbines (VAWTs) generate power using a main rotor shaft that is positioned vertically.
2 September 2010 22:00 GMT
Updated
25 November 2012 13:34 GMT