Another solar power plant play for Khosla, Idealab

A passel of high-profile high-tech investors  — including Khosla Ventures, Paul Allen’s Vulcan Capital and Bill Gross’ Idealab — are backing yet another new player in the increasingly hot market for large-scale solar power, pumping $50 million into Infinia, a Kennewick, Wash., company manufacturing a Stirling solar dish.

The Stirling dish has a storied — if unfulfilled - history in the annals of solar energy. It marries a Stirling heat engine, 17th-century invention, with a mirrored dish that looks like a super-sized version of a home satellite receiver. The solar dish focuses the sun’s rays on the Stirling engine, heating a gas inside that drives pistons to generate electricity. Stirling dishes are much more efficient at converting sunlight into electricity than solar thermal technologies that use mirrors to heat liquid-filled tubes to create steam to drive electricity-generating turbines. But while solar thermal plants exist today, the Stirling solar dish has never been deployed on a large scale since work on the technology began in earnest following the oil shocks of the 1970s.

Stirling Energy Systems of Phoenix in 2005 signed contracts with utilities Southern California Edison (EIX) and San Diego Gas & Electric (SRE) to build up to build tens of thousands of Stirling dishes to produce up to 1.75 gigawatts of greenhouse gas-free electricity. Though the company operates a six dishes in a prototype power plant at Sandia National Laboratories New Mexico, it is still working to get production costs down and rivals have questioned whether Stirling Energy Systems will be able to fulfill its deals. (See Green Wombat’s 2007 Business 2.0 magazine article on Stirling Energy Systems here. )

But Infinia CEO J.D. Sitton tells Green Wombat that his company has perfected the Stirling dish to make it competitive with large-scale solar thermal as well as new photovoltaic technologies like thin-film solar. Infinia aims to deploy its Stirling dishes in smaller configurations so that solar power plants can be located near cities and at other sites that don’t require vast stretches of desert land where solar thermal plants are typically built. Each 21-foot-high, 15-foot-wide solar dish can generate 3-kilowatts (compared to 25 kilowatts for Stirling Energy Systems’ dish).

Infinia won’t itself become a solar developer but will provide its dishes to for power plants that range in size from 1 megawatt to 150 megawatts or more. In contrast, most solar thermal power plants now being planned are in the 400-500 megawatt range.

“We fly in the face of what has been the conventional wisdom in the solar thermal field that to be competitive you have to have a very large system,” says Sitton. “We can be deployed within city limits and be connected to existing transmission systems. No additional transmission capacity is required.”

“Our approach is that the winning solutions will be those that generate for most kilowatts for the least cost,” he adds. “This is a game about capital efficiency.”

That, of course, has been the mantra of leading green tech investor Vinod Khosla, who has disparaged photovolatic solar systems as too expensive to displace fossil-fuel generated power. Khosla also is backing Palo Alto solar thermal startup Ausra, which last year signed a deal to supply solar electricity to California’s largest utility, PG&E (PCG). Serial entrepreneur Bill Gross’ Idealab is funding solar thermal startup eSolar, which also is being backed by Google (GOOG).

Infinia contends the design of its Stirling dish system makes it competitive with solar thermal technologies. First, the Stirling engine uses helium rather than hydrogen, which typically must be periodically replenished. “We have no lubrication inside the machine and it needs no maintenance,” Sitton says. “We use helium in a hermetically sealed system.”

Second, he says the Infinia dish is made of six panels of glass rather than the 76 panels on the Stirling Energy Systems dish. “That gives us lower production costs and lower capital costs,” says Sitton. “We brought in large-scale manufacturer from the beginning. It’s not like we built a prototype and now have to reduce the cost to produce it.”

The first prototype went online last October and Sitton says Infinia is building a second at Sandia. Field tests will be conducted later this year in California and Nevada. He says Infinia is currently negotiating with solar developers and full-scale production is set to begin in November. Infinia has been in business since the 1980s, building Stirling engines for other applications. But the green tech boom and demands from utilities for renewable energy led the company to focus on solar.

Whether Infinia beats Stirling Energy Systems to market remains to be seen but look for the deals it signs with solar developers for a good indication of just how viable its technology is likely to be.