Windmills farms. Solar panels on building tops. And now comes the latest entry into the alternative energy race: turbines spun with steam generated by superheated molten salt.

SolarReserve, a Santa Monica company founded in late 2007, announced Dec. 22 that it will build two solar plants with its molten salt technology. One project, the Rice Solar Energy Project near Blythe, will produce enough energy to power 68,000 homes. Pacific Gas & Electric Co. agreed to purchase the plant’s output for 25 years.

The same day, SolarReserve announced another 25-year purchase agreement with NV Energy in Las Vegas for the Crescent Dunes Solar Energy Project near Tonopah, Nev. That plant will produce enough energy for 75,000 homes.

These are the first SolarReserve projects approved in the United States. The Spanish government approved a plant there, but construction hasn’t started.

SolarReserve announced it plans to start construction for the Nevada plant in late 2010 once the company obtains financing. And there’s a lot to raise: The two plants will cost more than $1 billion. Chief Executive Kevin Smith said the company is in serious talks to get the money.

“These are large-scale projects, each well in excess of half-a-billion dollars to build,” Smith told the Business Journal.

Both plants will employ a molten salt system developed by Rocketdyne in Canoga Park, a unit of United Technologies Corp. The plants will feature as many as 15,000 billboard-size mirrors that reflect sunlight to a central tower where molten salt will be heated to 1,000 degrees. The salt moves through pipes and transfers its heat to water, producing steam that drives turbines, generating electricity. The salt cools to about 500 degrees as it is pumped back to the tower and reheated.

To date, SolarReserve has raised more than $140 million from seven private equity groups. To fund construction, Smith plans to bring in equity investors and lenders. Because he hopes to secure loan guarantees from the U.S. Department of Energy, Smith expects most of the money will come from commercial banks, which like the low risk associated with government-backed loans.

Jassi Cheema, a solar energy consultant at PA Consulting in downtown Los Angeles, said the funding of these projects will depend on whether backers have faith in the molten salt technology. Even if SolarReserve gets the DOE guarantees, banks will ask plenty of questions about the salt technology.

“Nobody has ever constructed a large-scale plant with this technology,” Cheema said. “Whoever lends will have to look at the technology.”

Solar Reserve’s Tonopah project will start generating revenue in late 2012, with the California project coming on line in 2013. Smith said the company has 20 projects in development worldwide and its business plan calls for building 30 to 40 plants in the next decade.