The amount of gas that can be stored to cover peak demand. The main types of storage (apart from pipeline storage) are:
1) Liquefied natural gas (LNG) – gas cooled until in liquid form at -162° Celsius and stored in insulated metal tanks.
2) Salt cavities (caverns) – many cavities have been created underground by dissolving layers of salt.
3) Aquifers (porous rocks).
4) Depleted gas fields now converted into storage facilities.