Palm Springs, UNITED STATES:  A windfarm is seen 30 December 2006 near Palm Springs, California. Increasingly popular as alternative sources of energy, wind turbine generators are a type of windmill that produces electricity by harnessing the wind. Wind turbine generators are much less harmful to the environment than burning fossil fuels, but they do require average wind speeds of at least 21 km/h (13 mph). The largest of these windmills stands 150 feet tall with blades half the legend of a football field. The compartments at the top containing the generator, hub and gearbox weigh 30,000 to 45,000 pounds. A wind turbine's cost can range upwards to USD 300,000 and can produce 300 kilowatts an hour -- the amount of electricity used by a typical household in a month. Almost all of the currently installed wind electric generation capacity is in California. The high-tech megatowers are engineered in cooperation with NASA and nursed by federal and state subsidies. This wind farm on the San Gorgonio Mountain Pass in the San Bernadino Mountains contains more than 4,000 separate windmills and provides enough electricity to power Palm Springs and the entire Coachella Valley. AFP PHOTO/GABRIEL BOUYS  (Photo credit should read GABRIEL BOUYS/AFP/Getty Images)
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