Harnessing high-altitude wind power


FREE-DOWNLOAD BW Roberts, DH Shepard, K Caldeira… – Energy Conversion, …, 2007 –

research TRANSACTIONS ON ENERGY CONVERSION, VOL. 22, NO. 1,

Flying electric generators (FEGs) are proposed toharness kinetic energy in the powerful, persistent high-altitudewinds. Average power density can be as high as 20 kW/m2in anapproximately 1000-km-wide band around latitude 30?in both thehemispheres of the Earth. At 15 000 ft (4600 m) and above, tethered rotorcraft, with four or more rotors mounted on each unit,could give individual rated outputs of up to 40 MW. These aircraftswould be highly controllable and could be ?own in arrays, makingthem a large-scale source of reliable wind power. The aerodynamics, electrics, and control of these craft are described in detail, alongwith a description of the tether mechanics. A 240 kW craft has beendesigned to demonstrate the concept at altitude. It is anticipatedthat large-scale units would make low-cost electricity available forgrid supply, for hydrogen production, or for hydro-storage fromlarge-scale generating facilities.