A big energy company plans to slash the number of wind-powered turbines to about 200 from more than 460 at its sprawling Mesa Wind Farm in the wind-whipped San Gorgonio Pass.

Western Wind Energy Corp. met with Bureau of Land Management officials Tuesday in Palm Springs as part of an effort to seek regulatory approval for a major overhaul that’s expected to take four to five years.

The company will slim down by bringing in bigger, more technologically advanced windmills that operate much more efficiently.

“We’re in the process of doing what’s called a re-powering of the project,” said Mike Boyd, Western Wind’s vice president of development in California. “We plan on gradually converting out the old and bringing in the new.”

Western Wind has yet to determine the exact type of wind turbines it will use, Boyd said.

But the Coquitlam, British Columbia-based company plans considerably larger turbines made of vastly improved materials that are manufactured by firms such as Clipper, GE, Mitsubishi and Vestas.

The new turbines operate more efficiently, helping bring down costs of generating wind power, Boyd said.

Some new turbines feature a 410-foot rotor diameter, compared with 33 feet in the 1970s.

Wind turbines have seen about as much improvement as computers over the past two decades, said Jan Johnson, spokesperson for Portland-based PPM Energy, which also is reducing the number of turbines at a local wind farm that will still generate just as much power.

Western Wind’s replacement process could begin within six months if the company garners regulatory approval.

The company is also scouting about 66 locations statewide for new windmill operations, including some desert areas in Riverside County.

Western Wind’s initiative comes as a host of factors are spurring new investments in wind power nationwide, experts said. They range from the recent extension of federal tax credits to more dollars being paid out by big utilities for green power.

A recent law passed in the California Legislature called for a statewide increase of renewable energy. All utilities are pushing to meet a goal of generating 20 percent of the state’s power needs from renewable sources by 2010.

As other states increasingly look to embrace green power, the result is that wind power generating capacity increased by 27 percent last year and is expected to increase another 26 percent this year, according to the American Wind Energy Association.

Last summer, Western Wind acquired PAMC Management Corp. for $13.4 million. That gave the company the Mesa Wind Farm assets near Palm Springs as well as a purchase contract to supply Southern California Edison with 120 megawatts of electricity a year for 20 years.

Western Wind’s Mesa Wind Farm was built 22 years ago as one of the first wind farms in San Gorgonio Pass. It generates about $5.4 million in revenue from electricity per year, company officials said.

Western Wind leases about 440 acres at the site from the Bureau of Land Management.