LOS ANGELES (Reuters) - U.S. Senator Dianne Feinstein introduced a bill on Monday to set aside over one million acres of California desert for wildlife and scenic conservation, closing those areas to renewable energy companies hungry for sunny, wide-open spaces.

Green Business

The measure marks the latest move by the California Democrat to protect ecologically fragile tracts of the Mojave Desert, putting conservation interests at odds with the search for large swaths of land suitable for solar power arrays and wind farms.

California has set some of the nation's most ambitious clean-energy goals, including a target to meet a third of the state's electricity needs from renewable resources by 2020.

But Feinstein has led efforts to prevent renewable energy expansion from spoiling pristine lands prized for their scenic values and regarded by scientists as crucial habitat for such species as bighorn sheep and desert tortoises.

"I strongly believe that conservation, renewable energy development and recreation can and must co-exist in the California desert," Feinstein said in a statement. She also was a chief sponsor of a 1994 law that bolstered protection for more than 7 million acres (2.8 million hectares) of desert.

Two energy projects that ran afoul of her efforts were canceled earlier this year -- a 500-megwatt solar thermal plant under development by BrightSource Inc and a sprawling solar complex planned by Stirling Energy Systems. Both concerns are privately held.

"We wanted to be respectful of what she's doing and it didn't make sense for us to develop that project further," said Stirling spokeswoman Janette Coates.

The Stirling project originally was planned for a panoramic stretch of desert called Sleeping Beauty Valley, included as part of the 941,000-acre (381,000-hectare) Mojave Trails National Monument now proposed by Feinstein's bill.

A second 134,000-acre (54,000-hectare) area near Joshua Tree National Park would be designated as the Sand to Snow National Monument. National monuments are similar to national parks and administered by the National Park Service.

The bill also would set aside 250,000 acres of public land as wilderness -- a more restrictive classification barring roads and permanent buildings -- near the U.S. Army's Fort Irwin training center; expand Death Valley National Park by 41,000 acres ; and add 2,900 acres to Joshua Tree Park.

BrightSource and Stirling are not alone. Various companies have filed more than 130 applications with the U.S. Bureau of Land Management to build solar arrays or wind turbine farms in California's desert.

To help accommodate such demands, the U.S. Interior Department has designated 670,000 acres of land especially for potential solar energy production in six western states.

And the agency recently fast-tracked the permit process for more than 2.4 gigawatts worth of renewable energy projects in California alone, including another Stirling solar venture.

In her bill, Feinstein included provisions to ease the permit process for large wind and solar projects on public and private lands in the California desert.

(Reporting by Laura Isensee, editing by Steve Gorman)