BrightSource Energy, a solar-thermal startup, has put aside its plans for an IPO because the company couldn’t attract enough interest from potential investors. In this feature last year, TR’s editor, David Rotman, explained the difficult economics for solar-thermal and other clean-energy technologies. BrightSource itself was a TR50 company in 2011. And don’t miss this picture of the huge facility BrightSource has been building in the Mojave Desert. The image conveys the scale of the company’s hopes.