The sweep-twist adaptive rotor (Star) is the first blade of its kind produced in utility-grade size. The gently curved tip, or sweep, is intended for regions like the Midwest where wind speeds average about 13 mph at 10-m high. Sweep lets the blade respond to gusts in a manner that lowers fatigue loads on the blade. Low-wind-speed sites are abundant in the U.S. the low-speed turbines could increase the land area that can be economically developed for wind energy twentyfold.
The 27.1-m blade, made of fiberglass and epoxy resin, is almost 3 m longer than the ones it will replace.