Airthium builds a new kind of energy storage system that stores electricity as heat - reversibly - and in the form of ammonia. The system relies on a high-temperature heat pump/heat engine to heat molten salt to 540°C (1000°F) and then convert the heat back into electricity, with a 70% roundtrip efficiency. Airthium's units can be used to store and deliver solar and wind energy, starting at 100 kW and up to GW scale (Utility). Moreover, an ammonia generation unit and an external ammonia burner can be added to the system to provide uninterruptible power or go off-grid, even after several days of bad weather (no sun/wind).