Natural gas is a major source of energy, but many towns and cities that need the energy are located far from the gas fields. Transporting gas by pipeline can be costly and impractical, so the IOC’s* cool natural gas to liquid to -160°C (-260°F), shrinking its volume for easier, safer storage and shipment overseas. LNG is a clear, colourless, non-toxic liquid that can be transported and stored more easily than natural gas because its occupies up to 600 times less space. Once the liquefied natural gas arrives at its destination, it is returned to a gas at regasification facilities and then piped to homes and businesses.
While LNG is reasonably costly to produce, advances in technology are reducing the costs associated with the liquifaction and regasification of LNG. Because it is easy to transport, LNG can serve to make economical those stranded natural gas deposits for which the construction of pipelines is uneconomical.
LNG, when vaporized to gaseous form, will only burn in concentrations of between 5 and 15 percent mixed with air. In addition, LNG or any vapor associated with LNG, will not explode in an unconfined environment. Thus, in the unlikely event of an LNG spill, the natural gas has little chance of igniting and explosion. Liquification also has the advantage of removing oxygen, carbon dioxide, sulfur, and water from the natural gas, resulting in LNG that is almost pure methane.
LNG is tipically transported by specialized tanker with insulated walls, and is kept in liquid form by autorefrigeration, a process in which the LNG is kept at its boiling point, so that any heat additions are countered by the energy lost of from LNG vapor that is vented out of storage and used to power the vessel. The use of LNG allows for the production and marketing of natural gas deposits that were previously economically unrecoverable.
*IOC: International oil companies