Stirling Energy Systems\u2019 unsubsidized business filed for Chapter 7 bankruptcy Sept. 29--selling off what\u2019s left of the company\u2019s assets. Its systems, as designed, would have used a parabolic mirrored dish to concentrate heat onto a sealed engine filled with hydrogen. As the gas heats and cools, pressure rises and falls. The pressure change drives a piston producing mechanical power that turns a generator. The company failed to get loan guarantees from the Department of Energy. Stirling was an early developer in California with projects including Solar One, Calico, and Imperial Valley Solar. They were sold to other companies over the last years, with the remaining viable projects located in Arizona.