New invention hailed as the "Holy Grail" of solar energy and "game changer" for the planet A Bill Gates-backed startup just announced a technological breakthrough in solar energy that could finally put fossil fuel to rest. The clean energy company Heliogen has developed a solar oven that reach temperatures a quarter as hot as the surface of the sun. That means solar energy just became powerful enough to fuel industrial processes it couldn't touch before. Until now, the extreme heat required to make cement, steel, glass and other industrial materials could not be generated efficiently by solar. But now, the scientists at Heliogen have figured out how to create a 1000-degree-celcius solar oven with a field of mirrors all aimed at a single point.