Because it can be stored indefinitely, natural gas is the most readily available of the fossil fuels. The exploration, production, and transportation of natural gas takes time. Often, when natural gas reaches its destination, it is not always needed immediately, so it is stored underground in large storage reservoirs strategically located all over the United States. These storage services can be near market centers that do not have a ready supply of locally produced natural gas. In addition to storage underground, natural gas can also be stored in liquid form known as liquefied natural gas or LNG. The advantage of LNG over gaseous natural gas is that it takes up much less space to store and ship.
Stored natural gas can act as insurance if any unexpected accidents, natural disasters, or unexpected consumer demand surges happen. Usually, natural gas has been a seasonal fuel with highest demand during the winter for heat. However, because of advantages natural gas has over other energy sources, its demand has increased to be used for more than just the winter months. Also, stored natural gas ensures that any excess supply delivered during the summer months is available to meet the increased demand of the winter months.
Shortly after World War II, the natural gas industry noted that seasonal demand increases could not be met by pipeline transfer alone. Reaching the growing demand in the growing consumer regions using the pipelines in existence then was not possible. The size and quantity of pipelines would have to increase dramatically. Making available Underground gas storage facilities was the answer. These facilities now play an important part in maintaining the supply needed to meet the energy fuel demands of consumers today. To ensure that adequate supplies of natural gas are available for seasonal and any unexpected demand shifts, underground storage is used to serve as a buffer between transportation and supply.
There are three types of underground storage: exhausted reservoirs, aquifers, and salt caverns. Companies like Triple Diamond Energy Corporation work to maintain all of these types of storage so the demand for power from natural gas can be satisfied. In depleted reservoirs, essentially, natural gas is injected into the formation vessel underground, building up pressure as more natural gas is added, becoming, in a sense, a sort of pressurized natural gas container. The higher the pressure, the more readily gas may be removed. If the pressure drops to below that of the wellhead, there is no pressure left in order to push the natural gas out of the storage facility. A certain amount of gas may never be extracted known as physically unrecoverable, and this is forever fixed in the formation underground.
Depleted gas reservoirs are the most common kind of natural gas storage. They are the most reasonable and easiest to develop, operate and maintain. They have already been tapped of their recoverable natural gas and just need to be filled again. From a practical stand point, using an already developed reservoir allows the use of the equipment left behind from when the field was last productive.
The least desirable and most expensive type of natural gas storage is aquifers. They are underground porous, permeable rock formations that act as natural water reservoirs and are usually used in areas without depleted reservoirs which are a better option. Primarily located along the gulf coast and in the northern states, another form of storage is using salt caverns which are formed out of existing salt deposits. Being much smaller than depleted gas reservoirs and aquifers, salt caverns can't hold enough volume of natural gas to be used as a dependable resource, but work for peak load capacity situations.