Rebecca Watson helped shape the BLM's first solar energy policy in 2004 as the assistant secretary for land and minerals management in the U.S. Department of the Interior. There were no applications from companies interested in developing large solar projects on federal land then, but Watson said the agency "wanted to get ahead of the curve."

Now, there are 125 applications pending for rights of way on federal land for solar projects.

"So, there's a real interest in renewable energy by utility companies," said Watson, who as an attorney in Denver represents some of those companies.

That interest exists among international companies as well as small startups, she added.

Interior Secretary Dirk Kempthorne said in a written statement Thursday that renewable energy will help the country meet its energy needs.

"Expanded solar energy development is part of the solution, placing more control over energy supply in the hands of America," Kempthorne said.

The BLM will consider various alternatives in an environmental impact statement, which would amend the agency's land-use plans in the six states. A similar analysis was done in 2005 for wind energy on federal land in 11 states.

Lands that will be excluded from the solar energy review include national monuments; areas designated as wilderness or under study for the designation; wild and scenic rivers; and national historic sites.

Additional environmental analysis would be done for individual projects.

Phil Hanceford of The Wilderness Society said he welcomes the BLM review.

"We do realize that solar energy development has great potential in the Southwest in general, and not just on federal land," Hanceford said.

Some of the best spots for solar energy development in the West are near large cities, such as Las Vegas, he added.

Hanceford said he agreed with BLM's approach of determining the best areas for solar energy and where plants shouldn't be built before development starts.