As someone who works in the wind industry I just want to add some facts into this discussion. VAWTs have been around for years and no one has successfully gotten them to work. Why? Extracting energy from the wind is all about capturing as much wind as possible. That means long blades and a big "swept area". It also means the turbine has to be up in the clear wind where there are no trees, buildings, or other obstructions to cause turbulence. The pictures at their web site showing the turbines in a park or on top of a building are ridiculous if they are serious about generating energy. Also, the towers are very expensive (lots of steel) so it is much more economical to put the largest turbine possible on one tower, not many smaller turbines are many towers.