A startup that makes compressed air energy storage technology called LightSail Energy, has raised a whopping $37.3 million series D round led by Peter Thiel, and also including existing investors Bill Gates and Khosla Ventures. LightSail Energy, based in Berkeley, Calif., has been in stealth for awhile, but the company makes a next-generation technology that compresses air in a tank and efficiently releases it on command, creating a sort of air-based battery for the power grid.