After months of debate over whether U.S. public land should be used to harness renewable energy, the Department of the Interior weighed in by approving two large-scale solar energy projects in California.

The projects will be the first solar energy projects in the country to be built on public land. Shortly after yesterday’s historic decision, the U.S. Department of the Interior released a statement in which its head, Secretary Ken Salazar, spoke about the benefits of the new solar installations:

“These projects advance the President’s agenda for stimulating investment in cutting-edge technology, creating jobs for American workers, and promoting clean energy for American homes, businesses and industry.”

The timing and location of the approvals is no coincidence, as California regulators have been racing against the clock in order to gain approval for nearly ten solar projects throughout the state before year’s end, when a helpful federal grant option is due to expire.

This year, the Bureau of Land Management (BLM) is likely to OK several more plants for construction on public land. In the end, it’s all part of a plan to more than double solar energy capacity in the United States by 2011; the two most recent approvals will play a helpful role in nearing that goal.

San Bernardino County,  highlighted above in red, will host one of the nation’s solar projects built on public land.

One of the newly approved projects will be a 709-megawatt (MW) solar thermal plant built by Tessera Solar in California’s Imperial Valley. Tessera took a a major step about a month ago when it gained approval for the project from the California Energy Commission (CEC). San Diego Gas & Electric, one of the state’s three major investor-owned utility companies (IOU’s), has already signed a power purchasing agreement (PPA) to buy the energy produced by Tessera’s plant.

The second plant will be a smaller 45-MW solar plant built by Chevron Energy Solutions on unincorporated land in southern California’s San Bernardino County. Because of the unincorporated status, Chevron did not have to gain approval from the  CEC like Tessera did.

Both Chevron and Tessera will be subject to the BLM’s “megawatt capacity fee”, which Uncle Sam charges companies that build on public land.