Molten salt is "secret sauce" of new solar energy technology

Just past the city of Barstow, Calif., on Interstate 15, Las Vegas-bound travelers can eye a tower resembling a lighthouse rising out of the desert encircled by more than 1,800 mirrors the size of billboards.

The complex is often mistaken for a science-fiction movie set, but it is actually a power plant that once used molten salt, water and the sun's heat to produce electricity.

Now a storied rocket maker and a renewable-energy company are hoping to take what they learned at the long-closed desert facility to build a much larger plant that could power 100,000 homes — all from a mix of sun, salt and rocket science once believed too futuristic to succeed.

The Santa Monica, Calif.-based energy company SolarReserve has licensed the technology, developed by engineers at Rocketdyne.

"Molten salt is the secret sauce," said SolarReserve President Terry Murphy.

It is one of at least 80 large solar projects on the drawing board in California, but the molten salt technology is considered one of the more unusual and — to some energy analysts — one of the more promising in the latest rush to build clean electricity generation.

"It's actually something we'll likely see in a few years," said Nathaniel Bullard, a solar-energy analyst with New Energy Finance in Alexandria, Va. "It's moving along in a nice way and they have good capital behind it."

Talks with utilities

SolarReserve, which is financing and marketing the project, said it is working on agreements with several utilities to buy electricity generated from the plant. It hopes to have announcements in a few months that could help jump-start construction of the first plant, likely on private land in the Southwest, Murphy said.

The company last fall secured $140 million in venture capital.

The plant could begin operating by 2012 or early 2013. It would use an array of 15,000 heliostats, or large tilting mirrors about 25 feet wide, to direct sunlight to a solar collector atop a 600-foot-tall tower — somewhat like a lighthouse in reverse.

The mirrors would heat up molten salt flowing through the receiver to more than 1,000 degrees Fahrenheit, hot enough to turn water into powerful steam in a device called a heat exchanger. The steam, like that coming out of a nozzle of a boiling tea kettle, would drive a turbine to create electricity.

The molten salt, once cooled, would be pumped back through the solar collector to restart the process.

"The plant has no emissions, and if you have a leak or something, you can just shovel it up and take it home with you to use for your barbecue," Murphy said.

Need lots of water, land

But some environmentalists have criticized solar-thermal plants for requiring vast tracts of land as well as precious water for generating steam and for cooling the turbines.

The array of the mirrored heliostats for the SolarReserve plant would take up about two square miles. Transmission lines also would be needed to transport the power where it's needed. With dozens of solar, wind and geothermal projects planned for California's deserts, some fear this unique habitat will be destroyed.

But SolarReserve officials said its plant would use one-tenth the amount of water required by a conventional plant and that mirrors will be "benign" to the environment.

The technology, with the exception of using salt, is similar to those that Rocketdyne engineers developed for the nation's more notable space programs.

Space technologies

At the sprawling Canoga Park, Calif. facility, the engineers who came up with the SolarReserve technology also developed the power system for the international space station, the rocket engine for the space shuttle and the propulsion system for the Apollo lunar module.

Rocketdyne's aerospace heritage stretches back to the earliest years of rocket development when it was founded shortly after World War II to study German V-2 rocket technology. After becoming part of Rockwell International in the late 1960s, the company was sold to Boeing in 1996.

United Technologies bought the Rocketdyne unit from Boeing for $700 million in 2005 primarily for its expertise in rocket engines. It didn't know about the solar project until after the acquisition.

The solar-thermal technology actually was proved workable more than a decade ago at the Barstow pilot plant. But the complex was shuttered in 1999 when the cost of natural gas fell to one-tenth of what it is today.