A means of maintaining a reserve of natural gas to allow supply to match demand, either on a daily, level or a seasonal level. Stored gas helps protect downstream markets, to balance the system and to prevent supply interruptions.

Natural Gas Storage works on 3 different levels, with each level fulfilling a different role and usually requiring a different type of storage although some storage reservoirs can be used for all three purposes:

Daily or hourly storage: mostly for linepack purposes. This is very short time storage to meet daily peak consumption needs. Usually the storage is filled at night and used during day hours.

Monthly or seasonable storage: storage to meet periodical differences in demand with storage being filled during low consumption months and used during higher demand seasons

National or strategic storage: for large quantities of gas that can replace a natural gas supplier in time of need.

Storage is required in order to meet high seasonable demand for natural gas (i.e. during cold winter months in Europe and the US). Since the system works most efficiently with a constant flow throughout the year, gas is put into storage during lower summer demand periods to be used during peak times. Storage is also used for balancing purposes and/or in times of supply disruption. Heating demand for natural gas during winter in Europe and the US puts upward pressure on natural gas prices. The commercial use of gas storage played a critical role in mitigating the effects of the Ukraine-Russia row in January 2009. During normal first quarters of the year, storage is normally consumed at a rate of 2.5% a week. But in the second two weeks of January, when the gas dispute saw no gas flow from Russia to Europe via the Ukraine, the rate was 15%. However, it should also be recognized that storage will always have a finite duration of stock and deliverability per day. Experts believe that existing and new commercial storage is critical to guaranteeing security of supply, working alongside additional gas supply routes and LNG regasification facilities to secure energy supply. Currently, planned commercial storage projects in Europe total 60 bcm of new capacity by 2015.