The capacity of energy storage can be choosen between 1 and 10 GWh, comparable to large Pumped Hydro Storage.

The rock piston should have a diameter of at least 100 meters/ 300 ft. in order to be competitive with other bulk storage solutions. The Levelized Costs of Storage (LCOS) vary between 0,09 and 0,18 $ per kWh. Investment costs vary between 120 and 380 USD per installed kWh.