Three solar-thermal companies have raised money in the past week in a sector that's showing life, despite a choppy investment environment.
On Monday, eSolar said it has raised $130 million from Idealab and Google.org. Its solar-thermal systems, designed for utility-scale power plants, use mirrors to reflect light onto a tower that turns a turbine.
Stirling Energy Systems makes a huge concentrator dish that generates heat to turn a Stirling engine that makes electricity. It's under contract for two power plants in the Mojave Desert that would initially generate 800 megawatts of power.
Solar-thermal technology has been around for decades, and Stirling engines date back to the 19th century. But the high cost of silicon-solar cells has made solar-concentrating systems more attractive in desert areas like the Southwest United States and Spain.