Theoretical analysis of an airborne wind energy conversion system with a ground generator and fast motion transfer

• An airborne wind energy conversion system with fast motion transfer is described.
• The fast motion transfer is achieved by using a motion transfer belt, separate from tether.
• System parameters are calculated accounting for tether drag and weights.
• Economic effect is estimated using comparison with conventional wind turbines.

A novel airborne wind energy conversion concept is presented, in which the wind power, which is harvested by the crosswind motion of a tethered wing, is transferred to a ground-based generator by a belt with a high speed close to the speed of the wing. The belt trails behind the wing. The high speed of the motion transferring belt results in a low belt tension, a high rotational speed and a low torque on the shaft connected to the rotor. The theoretical analysis and numeric calculations, which consider the drag of the tether and the weight of both the tether and the wing, demonstrate the practical feasibility of the concept. Two practical constructions are described, one with a single wing and one with two wings in counter phase. The economic analysis shows that the proposed system is 10 times less expensive than a conventional wind turbine with a comparable average power output.