Engineers have been trying to build efficient wind turbines to generate electricity for decades. A new approach by The Wind Turbine Co., Bellevue, Wash., could be the key to bringing the cost of wind-generated electricity down to $0.035/ kW-hr. One way they plan to do this is by using a hinged-rotor system that reduces out-of-plane bending moments by orders of magnitude compared to wind turbine designs with rigidly attached rotor blades. A blade-pitch control adjusts pitch continuously in response to blade flapping, further reducing the loads caused by changing winds. Reducing these loads lets the company erect less robust towers to support the blades and generators. The downwind design, that is, with the nacelles and blades mounted on the downwind side of the tower, gives the company the option of mounting their turbines on guy-cable supported towers. Guy-supported towers cost 60% as much as freestanding towers of identical height.

The company's WTC 750 model, its first commercial model, will have a two-blade, 60-meter-diameter rotor and generate 750 kW. It works when winds are between 5 and 24 m/sec (roughly 10 to 50 mph) and uses a single-speed induction gearbox.