Perhaps you've heard the saying, "We're not running out of oil. We're running out of easy oil." One place where oil is hard (and heavy) is below the Californian ground, where extractors must blast the sludgy petroleum with steam to get it flowing. Most such operations use natural gas to make the steam, but one startup has turned to an unusual partner for oil mining—solar energy—to try to make the business more efficient. How? Greenhouses full of mirrors. GlassPoint, a company based in Fremont, California, wants to use solar thermal energy to cook up some steam. Unlike photovoltaic solar, which converts the sun's radiation directly into electricity, solar thermal projects trap and focus the sun's heat. Those projects typically involve using the heat to turn turbines and create electricity, but this design is simpler.