While renewables are advancing faster than anyone could have imagined in terms of efficiency and price, we still don’t have the storage capabilities needed to transition entirely to clean energy. Lithium batteries are amazing for storing energy in electric cars, but they’re too expensive to be used for the grid. The good news is researchers have found a cheap, effective and durable alternative to the lithium battery that uses molten salt instead. The discovery could soon allow cities to safely and easily ramp up the amount of renewable in its energy mix.