The fundamental idea of Gravity Storage is based on the hydraulic lifting of a very large rock mass using water pumps. The rock mass acquires potential energy and can release this energy when the water under pressure is discharged back through a turbine where the water generates electricity like in any other hydro power station.
The outstanding advantage of Gravity Storage compared to other storage technologies is its huge storage capacity. It increases with the fourth power of the piston´s radius, r4, which allows capacities up to 10 GWh or even more.
The construction costs however only increase with the square of the radius, r². This means that with a wider radius the construction costs increase substantially more slowly than the storage capacity. Thus, very low costs per kilowatt hour of storage capacity are possible. Scientifically speaking, the price per kilowatt hour of storage capacity decreases with 1/r².
Storage capacity with different sizes
Usable Capacity [GWh]
The efficiency of a Gravity Storage of 80%, is comparable to a pumped hydro storage.
The water used again and again is kept in a basin. The separation of the piston is mainly done with wire saws. The patented seal withstands the prevailing maximum pressure of up to 80 bar.