The secretive lab that’s famous for Google Glass and Internet balloons is trying to solve a big problem facing clean energy: how to meet demand when there’s no sunshine or wind. So far, adding batteries to the grid in order to save excess electricity for later uses has proven expensive, though Elon Musk is doing all he can to make it a reality. The X lab has another idea: it hopes to store energy as heat in molten salt. That’s not a new idea (at all). But the folks at X say that its scheme, codenamed Malta and based on theories by Stanford physicist Robert Laughlin, has been designed to run at lower temperatures than competing systems. In turn, that means that it can make do with lower-grade, cheaper materials in its hardware, which should drive down the cost of an installation. The lab is currently experimenting with prototypes and looking to find a partner to build and test a megawatt-scale version that’s connected to the grid. Then we’ll see if the idea’s worth its salt.