Airthium builds a new kind of energy storage systems, that store electricity as heat - reversibly. 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, at a typical cost of 110$/kWh without installation. Airthium's units can be used to store and deliver solar and wind energy, starting at 30 kW (small office or workshop) and up to GW scale (Utility). Moreover, a diesel/biomass burner can be added to the system, to heat up the molten salt after several days of bad weather (no sun/wind). This allows to provide uninterruptible power, or go off-grid. Airthium plans to sell its combined storage/generation units to industrial/commercial buildings in developing countries, in areas where electricity is expensive or unstable, as a drop-in replacement of their diesel engines that could also store energy efficiently. Please see Airthium's website for more information.