Hydrogen CAES follows the same core cycle as conventional CAES: surplus energy compresses air into a salt cavern, and stored air is later released through a standard gas turbine to regenerate power. It is a reconfiguration of the McIntosh, Alabama CAES plant design (operating since 1991) and a conventional combined-cycle plant, using a different arrangement of existing, off-the-shelf equipment rather than bespoke components.

The key difference is the reheat stage. On discharge, air released from the cavern passes through a combustor and is reheated by burning gas, hydrogen, or a blend, before driving the expansion turbine. This reheat step means less compressed air, and therefore less cavern volume, are needed to generate a given amount of power, which is what drives the cost reduction. In addition, the gas turbine can be run in simple-cycle mode once the cavern is depleted. This process achieves efficiencies similar to those of a conventional combined-cycle plant.

Because the combustor can run on any gas-to-hydrogen ratio, the plant does not need replacing or major retrofitting as the gas network decarbonises.