long-duration-energy-storage

Fourth Power is a grid-scale thermal energy storage company building a "thermal battery" that stores electricity as heat. Surplus wind and solar power is used to heat blocks of graphite to roughly 2,400 degrees Celsius; molten tin, circulated by an all-ceramic pump, moves that heat in and out of storage, and thermophotovoltaic (TPV) cells convert…

Form Energy is a long-duration energy storage company headquartered in Somerville, Massachusetts and Weirton, West Virginia. Its flagship product is an iron-air battery designed to store electricity for up to 100 hours, intended to enable utilities and grid operators to firm renewable generation across multi-day weather events, replace aging…

Sizable Energy is a Milan, Italy based clean-energy company developing offshore pumped hydro energy storage. Its patented system pairs subsea and floating reservoirs connected by pipes with reversible pump-turbines that move saturated sea-salt brine between them to deliver long-duration, grid-scale energy storage.

EnerVenue is a Fremont, California-based energy infrastructure company building long-duration stationary energy storage using a metal-hydrogen (nickel-hydrogen) battery chemistry derived from NASA-heritage technology that has powered the Hubble Space Telescope and the International Space Station since the 1980s.