The Basics of Liquefied Natural Gas LNG
When LNG is received at most terminals, it is transferred to insulated storage tanks that are built to specifically hold LNG. These tanks can be found above or below ground and keep the liquid at a low temperature to minimize the amount of evaporation. If LNG vapors are not released, the pressure and temperature within the tank will continue to rise. LNG is characterized as a , a liquefied gas kept in its liquid state at very low temperatures. The temperature within the tank will remain constant if the pressure is kept constant by allowing the boil off gas to escape from the tank. This is known as . The boil-off gas is collected and used as a fuel source in the facility or on the tanker transporting it. When Natural Gas is needed, the LNG is warmed to a point where it converts back to its gaseous state. This is accomplished using a process involving heat.
Natural gas may be stored in a number of different ways. It is most commonly stored underground under pressure in three types of facilities. The most commonly used in California are depleted reservoirs in Oil and/or gas fields because they are more available. Aquifers and salt cavern formations are also used under certain conditions. The characteristics and economics of each type of storage site will dictate its suitability for use. Two of the most important characteristics of an underground storage Reservoir are its capability to hold natural gas for future use and its . The deliverability rate is determined by the withdrawal capacity of the associated valves and compressors and the total amount of gas in the . In other states, natural gas is also stored as LNG after the natural gas has been liquefied and placed in above-ground storage tanks. (Source: U.S. Department of Energy, Energy Information Administration.)