The purpose of natural gas storage is primarily to meet seasonal demand. Gas is injected into storage during periods of low demand and withdrawn from storage during periods of peak demand.
The most important type of gas storage is in underground reservoirs, consisting of depleted gas reservoirs and salt cavern reservoirs. Storing liquefied natural gas (LNG) is also critical in the energy chain.
Depleted reservoirs are used as storage facilities by injecting natural gas back into the porous underground rock that once held the fuel before it was extracted. Salt is impermeable and self-sealing, so it creates exceptionally strong and environmentally sound storage. Salt caverns can extend more than 1,000 feet underground. In fact, their vertical height can be greater than a major skyscraper is tall. LNG is made by refrigerating natural gas to condense it into a liquid. The liquid form is denser than natural gas, so it has much more energy for the amount of space it occupies, making it an efficient storage solution for natural gas.