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.

Indeed, the success of the prototype at Rocky Flats comes at a crucial moment in the evolution of wind power. Wind-driven generators are still a niche technology-producing less than one percent of U.S. electricity. But last year, 1,700 megawatts' worth of new wind capacity was installed in the United States-enough to power 500,000 houses-nearly doubling the nation's wind power capacity. And more is on the way. Manufacturers have reduced the cost of heavy-duty wind turbines fourfold since 1980, and these gargantuan machines are now reliable and efficient enough to be built offshore. An 80-turbine, $245 million wind farm under construction off the Danish coast will be the world's largest, and developers are beginning to colonize German, Dutch and British waters, too. In North America, speculators envision massive offshore wind farms near British Columbia and Nantucket, MA.