Windmills are sprouting across the United States, as Americans search for non-polluting alternative energy sources. The West Coast state of California is the U.S. leader in wind power.

Wind turbines dot hillsides in several parts of the state, including Tehachapi, in the desert northeast of Los Angeles.

Lee Brace of G.E. Energy stands beneath a slow-spinning propeller, attached to a wind turbine that his company is testing. "The larger the blade, it seems the slower they move. You're looking at 58 meters blades, and three of them on top of the tower there, about 240 feet up in the air."

The tower is 75 meters tall, and atop it is a one-point-five megawatt turbine, which provides enough power for 500 houses.

More than 4,000 wind turbines dot these desert hillsides. Some date from the 1980s and are just a fraction of the size and output of this model.

Down the road, Oak Creek Energy Systems operates 200 turbines, including another massive one-point-five megawatt test model. Michael Burns sits in front of a bank of computer monitors, which use color codes to track the temperature and status of the windmills. "The green ones are on line. If it's white, it means the turbine is off. Everything is all right on it but there isn't enough wind. And like a click on the turbine and find out the status survey California gives birth to the wind industry in the United States, but 16 other states, from North Dakota to Kansas, have greater potential, according to the American Wind Energy Association. Texas now ranks number two in wind production for the country.

But the association says the source remains largely untapped, providing less than one percent of U.S. electrical generation. Denmark, by contrast, gets 20 percent of its power from the wind. Linda White of the Kern Wind Energy Association, based in Tehachapi, says alternative energy sources can supplement dwindling supplies of coal, oil and natural gas, which provide most U.S. electrical generation. "As long as the wind is there, the water is there or the sun is there, we will have those renewable resources. And I think if we were to have much more of a mix or put more sustainable or alternative energy sources within our current mix, it will extend the life of those finite fuels," she said.

Government incentives in places like California are promoting the use of renewable energy sources. Ed Duggan of Oak Creek Energy Systems says, with better planning, utility companies can make more efficient use of available energy. "Maybe on a windy day, you hold the water behind the dam and save that energy for the days that the wind doesn't blow. Or maybe you keep your gas-fired peaking generator turned off on a windy day, but you run it on a day while it's a hot day when all the air conditioners are on in Los Angeles."

The industry still has work to convince Americans of the virtues of wind power. Some residents complain the large towers are unsightly, and environmentalists have criticized the windmills as dangerous to birds. This is more of a problem at another site in Northern California, which is on a migration route. In response to complaints, owners have agreed to a temporary shutdown of some of that area's wind turbines during this year's winter migration.

Michael Sullivan, VOA news, Los Angeles.