Ongoing research at MIT shows a promising technology that could provide a long-sought way of leveling the load of renewable energy sources at far lower costs and with greater longevity than previous methods. The system uses high-temperature batteries whose liquid components, naturally settle into distinct layers because of their different densities. The three molten materials form the positive and negative poles of the battery, as well as a layer of electrolyte in between. All three layers are composed of materials that are abundant and inexpensive, which would make them more attractive to utility companies looking to save costs. The inspiration for the concept came from the electrochemistry of aluminum smelting, which is conducted in electrochemical cells that operate at similarly high temperatures.