infinia-logo.jpgEarlier this week, we wrote about setbacks at some Silicon Valley companies with new solar technology.

They’re built on real science and work in the labs, but they’re grappling with the real-world manufacturing stage.

Infinia, of Kennewick, Wash., is another example of this. It has just raised more cash to help it develop products based on the “Stirling engine,” which creates electricity by processing various types of fuel, and by using heat differentials to drive a piston back and forth. Its work is based on invention of Robert Stirling in 1816, and on almost 20 more years of additional research since Infinia was spun out as a company from the University of Washington.

It has gotten $9.5 million in a new round of funding, and follows $3.5 million it raised two years ago. Backers are Khosla Ventures, Vulcan Capital, Equus Total Return and Idealab, along with existing investor Power Play Energy, it said in a statement yesterday.

The deal also includes the acquisition of Stirling Cycles, a company developing Stirling engine technology, from Idealab for an undisclosed sum, and which has also been working on the Stirling process for years.

Infinia is now applying the engine to solar energy. It says the process is more efficient that existing photovoltaic methods, however it is first expected to be available in 2008. It will concentrate solar energy for commercial and residential customers. Notably, the company says some of the funds will be used for product development; a working prototype will be ready by fall, it says. Stirling Cycles was also working on solar energy.

Besides the solar version, the company is also working on a bio-gas fueled Stirling generator for rural areas of developing countries.

Famed inventor Dean Kamen has also been working on Stirling engines for quite some time.