Liquefied natural gas (LNG) is natural gas that has been cooled to a liquid state, at about -260°Fahrenheit, for shipping and storage. The volume of natural gas in its liquid state is about 600 times smaller than its volume in its gaseous state. This process, which was developed in the 19th century, makes it possible to transport natural gas to places pipelines do not reach and to use natural gas as a transportation fuel.
For large-volume ocean transport, LNG is loaded onto double-hulled ships, which are used for both safety and insulating purposes. Once the ship arrives at the receiving port, LNG is off-loaded into well-insulated storage tanks, and later re-gasified for entrance into a pipeline distribution network.
LNG can also be shipped in smaller quantities, usually over shorter ocean distances. There is a growing trade in small-scale LNG shipments, which are most commonly made using the same containers used on trucks and in international trade, specially outfitted with cryogenic tanks. Other small-scale LNG activities include “peak-shaver” liquefaction and storage facilities, which can hold gas compactly for when it is needed in local markets in the U.S. during times of peak demand. LNG is also sometimes imported or exported by truck from this kind of facility.
LNG increases markets for natural gas.
Where natural gas pipelines are not feasible or do not exist, liquefying natural gas is a way to move natural gas from producing regions to markets, such as to and from the United States and countries in Asia or Europe. LNG is shipped in special ocean-going ships (tankers) between export terminals, where natural gas is liquefied, and import terminals, where LNG is returned to its gaseous state (re-gasified). At an import terminal, it can be injected into pipelines for transmission to distribution companies, industrial consumers, and power plants.
Most LNG is transported by large ships/tankers called LNG carriers that are equipped with onboard, super-cooled cryogenic tanks. LNG is also transported in relatively small volumes on ships using International Organization for Standardization (ISO)-compliant containers and on trucks.
LNG can be used as a fuel for ships, trucks, and buses with specially designed fuel tanks. Some power plants store LNG and use it to generate electricity when electricity demand is high and their natural gas demand exceeds pipeline delivery capacity.
TECHNICAL SPECIFICATION OF LNG