Storage 80 - 120 MW, 5 hours non-heating and heating
In a pair of caverns having a geometrical volume of 800 000 and 1 600 000 m3 1 100 MWh can be stored. Using air as gas a power of 80 MW can be obtained during discharge. If heat is added to the gas this can be augmented to 120 MW for a period of 5 hours. The effiency is app. 70 %.
This example is for a storage being used to stabilize the national grid. Of course it can be used for longer periods and smaller power.
The pressure and temperature changes in the caverns are small so that they would meet the regulations in order to consider rock mechanical constraints. The example is calculated for air. Unheated natural gas would give a smaller power at the same gas flow rate of 1.6 milliion sm3/h. Heated natural gas would expose the same power as air. The reason for this behavior are different molecular weight and heat capacity of the gases.
Storage in small surface units
The CAES energy storage is not limited to to salt caverns, but can be built in smaller units using e.g. burried pipes as storage volume or concrete vessels.
or in very small units in home size scale.