LOS ANGELES -- In a blustery stretch of desert two hours east of here, where many of the world's first power-producing windmills were built, a plan for more turbines has triggered a backlash that echoes a national debate over the merits of wind energy.

A proposal to build 50 windmills next to Santa Rosa and San Jacinto Mountains National Monument has aroused passions in a region already dotted with 3,000 windmills, with opponents charging that the wind energy industry has neither delivered the promised power nor spared the environment. The industry, born in California, has projects in 40 states and $8 billion in investments over the last two years, according to the American Wind Energy Association.

Supporters say wind power has come of age and will help slow global warming, while critics contend that it has delivered only a quarter of its promised energy, proved lethal to wildlife and, in the view of many residents, blighted the landscape.

Around the country, Internet blogs and anti-wind energy Web sites hum with angry postings about projects on picturesque ridgelines, seascapes and farmlands from New England to Texas.

Politicians and celebrities have weighed in. Sen. Edward M. Kennedy, D-Mass., and his Nantucket Island neighbors so far have successfully fought installation of offshore turbines. Their opposition, in turn, has prompted criticism that rich liberals are all for alternative power providing it doesn't mar their views.

In his San Gorgonio Pass neighborhood, homeowner Les Starks has led the local opposition.

"They're going to take a national monument ... and turn it into an industrial slum," Starks shouted, his voice nearly drowned by blustery gusts. "They want to bulldoze that mesa, put in these enormous wind turbines ... and make lots and lots of money."

San Gorgonio Pass is one of the windiest spots in North America, according to federal researchers. The 3,000 existing turbines produce enough energy to power almost 25,000 homes for a year, said California Energy Commission spokeswoman Amy Morgan.

Although politicians and environmentalists concede that there are drawbacks to wind energy, most argue that the fallout from the turbines is minor compared with the global harm threatened by burning fossil fuels.

Critics, however, argue that wind projects subsidized with public money deliver a fraction of the promised power. For example, in 2003, San Gorgonio wind farms boasted of 413 megawatts of capacity, but actually produced a quarter of that electricity.

Advocates concede that turbines have produced full power just 10 percent of the time, but said newer machines provide some power 60 percent of the time. Today, wind energy provides less than 1 percent of the nation's power.

Converting 5 percent to wind "would require ... almost 10 million acres, most of it rural and wild, turned over to 400-foot-high machines and their motion, noise and lights," wrote Lloyd Crawford of National Wind Watch, an online coalition of anti-wind power opponents. "That's not a green solution, but a huge disaster."

In California, turbines as big as minivans have caught fire in midair and crashed 200 feet to the Earth. Broken propeller blades don't budge, no matter how brisk the breeze. Thousands of hawks, eagles and songbirds have been killed by turbines. Favorite picnic sites and scenic back roads were closed to the public after government land was leased for private windmills.

Near San Gorgonio Pass, residents complain of a ceaseless high-pitched whine from windmills and, at night, bright, revolving lights.

"It's like having a disco going ... all night long," said Joyce Manley, a retired Los Angeles schoolteacher who lives within half a mile of hundreds of windmills.

Randall Swisher, head of the American Wind Energy Association, said "the California experience is different than any other state in regard to being home to first-generation technology which didn't work all that well -- some of the first-generation turbines didn't work at all."

Swisher said newer, larger turbines replacing flawed smaller ones are the solution. But they still don't produce 100 percent capacity because the wind doesn't always blow. And he said there is no stopping the fact that wind energy has come of age, with widespread public support.

"This is not a marginal, boutique industry any longer," he said. "It's a serious contributor to the nation's electric power needs."