I came accross this site
http://www.windwandler.de/eng/product_eng.html
Some of the claims made by this site...
Herr Josef claims that they are 53% efficient, as opposed to 46% for conventional bladed turbines, and the theoretical maximum efficiency that can be attained is 59%
The turbines are designed to be quieter when they rotate, which he says, is because they have no blade tips to shed vortices.
Rotation speed at 24m/s wind is 1,400 rpm, but remains the same at 30m/s because surplus high speed air then tends to spill round the rotating turbine. The turbines turn naturally into the wind.
Output at 14m/s is about 1 kW. The disk armature generator is rated at 3.5kW and, unlike bladed turbines, they do not have to be stopped in high winds.
What do you guys think about this design?