California (plus other states)

Academic research on underground hydrogen storage (UHS) and geologic engineering

Underground natural gas storage and hydrogen pilot projects

Use of inert or less-reactive gases (CO2, N2, CH4, or H2) to maintain minimum reservoir pressure and avoid water invasion during storage cycles.

A process whereby hydrogen gas, produced typically via electrolysis powered by renewable energy, is injected into depleted hydrocarbon reservoirs for interim (seasonal) storage and later withdrawn to meet energy needs.