The concept of underground gas storage is based on the natural capacity of geological formations such as aquifers, depleted oil and gas reservoirs, and salt caverns to store gases. Underground storage systems can be used to inject and store natural gas (NG) or hydrogen, which can be withdrawn for transport to end-users or for use in industrial processes. Geological formations can additionally be used to securely contain harmful gases, such as carbon dioxide, deep underground, by means of carbon capture and sequestration technologies.