American Superconductor Corp. (AMSC, Devens, Mass.) announced on Feb. 10 that it has entered into a 12-month Cooperative Research and Development Agreement (CRADA) with the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL, Golden, Colo.) and its National Wind Technology Center (NWTC) to validate the economics of a full 10-MW class “direct-drive” superconductor wind turbine. AMSC Windtec, a wholly owned subsidiary of AMSC, will analyze the cost of a superconductor wind turbine, which will include a direct-drive superconductor generator and all other components, including composite rotor blades and the rotor hub, the turbine nacelle and the tower as well as power electronics and controls. The NWTC will benchmark and evaluate the wind turbine’s economic impact, both in terms of its initial cost and its overall cost of energy.

Direct-drive wind generator systems use high-temperature superconducting (HTS) wire instead of copper wire for the generator’s rotor and are expected to be much smaller, lighter, more efficient and more reliable than conventional turbines. AMSC estimates that its superconductor system will weigh ~120 metric tonnes (~264,550 lb), compared with ~300 metric tonnes (~661,390 lb) for conventional direct-drive generators with the same power rating. In addition, direct-drive generators eliminate the need for massive gearboxes, the components with the highest maintenance costs in conventional wind turbines. The company claims the technology will open up the opportunity for the development of wind farms in more areas, both on land and offshore. Additionally, technology has been proven for superconductor ship-propulsion motors and generators under contracts with the U.S. Navy, says AMSC.