The newest wind turbine standing at Rocky Flats in Colorado, the U.S. Department of Energy's proving ground for wind power technologies, looks much like any other apparatus for capturing energy from wind: a boxy turbine sits atop a steel tower that sprouts two propeller blades stretching a combined 40 meters-almost half the length of a football field. Wind rushes by, blades rotate, and electricity flows. But there's a key difference. This prototype has flexible, hinged blades; in strong winds, they bend back slightly while spinning. The bending is barely perceptible to a casual observer, but it's a radical departure from how existing wind turbines work-and it just may change the fate of wind power.

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