When natural gas is cooled at normal pressure to about -260 ° F, it condenses into a liquid form known as Liquefied Natural Gas (LNG). LNG takes up about one six hundredth the volume of gaseous natural gas making it very efficient to transport. When it is necessary to transport natural gas energy to stranded or mountainous destinations, shipping it as LNG is much more practical. The absence of a pipeline infrastructure to these areas make direct connection of small gas utilities to the pipeline grid impractical.
Liquefied Natural Gas when vaporized to gaseous form, will burn in concentrations of between only 5 and 15 percent mixed with air. Another advantage is that LNG, or any vapor associated with it, will not explode in an unconfined environment. In the unofficial event of an LNG spill, the natural gas has little chance of ignoring an explosion. The process of turning natural gas into a liquid form removes from it, oxygen, carbon dioxide, sulfur, and water, resulting in almost pure methane. LNG is a clean fuel and a safe fuel.
Liquefied Natural Gas is usually transported in specialized tankers with insulated walls. The process of auto refrigeration in these tankers is used in which the LNG is kept at its boiling point, so that any heat additions are countered by the energy lost from LNG vapor that is vented out of storage and used to power the vessel. This is another example of the efficiency of LNG.
LNG storage facilities continue to be important in meeting peak demand needs of local utilities and also provide a more economic way to store gas until it is needed. Several niche markets, such as vehicular fuel and using it as an alternative energy to propane for facilities off the pipeline grid, keep LNG in an increasingly high demand whether its domestic or foreign sources. Replacing propane or other fuels in certain isolated industrial sites such as mineral extraction and forest product facilities has proven to be economically effective. Growth depends on expansion of current facilities and new construction. The need for additional supply sources to meet projected US demand generally coincides with numerous developments in LNG trade on a worldwide basis.
Although Liquefied Natural Gas currently accounts for a small percentage of natural gas used in the United States, it is expected that LNG imports will provide a steady, dependable source of natural gas for US consumption. Domestic natural gas exploration companies like Triple Diamond Energy Corporation continue to locate new sources of natural gas as well. Since 2001, companies have announced plans for the construction of LNG import facilities to serve US markets. LNG imported to the United States comes via ocean tanker, and receives the majority of its LNG from Trinidad and Tobago, Qatar, and Algeria. Some other shipments arrive from Nigeria, Oman, Australia, Indonesia, and the United Arab Emirates.