Wouter, I have often wondered why they don't use smaller diameter blades, but put more of them up and down the support tower, so they are all operating in their own little wind speed, not covering the huge difference from 20M height to 120M height.

Why not put 5 smaller ones, say 20M diameter each, up a tower, each able to swivel into it's own wind, as not only the speed but also the direction of the wind changes in that 120M altitude. I know they wouldn't produce as much juice as one big one, but they would be MUCH cheaper to build, able to operate at much higher windspeeds, and you wouldn't have all the vibration problems...and you wouldn't have to shut them down when things aren't "perfect" so you actually might end up with MORE juice (electricity) in the long run. <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />