text: High altitude wind power research and development centers freequently are dependent on blade autorotation: SkyMill Energy,Joby Energy,Sky Windpower, BaseLoad Energy, Magenn Power, and Makani Power are making and testing airborne wind energy conversion systems (AWECS) that emply autorotation of blades to drive the shaft of generators to make electricity at altitude and send the electricty to earth via conductice tethers.