Liquified Natural Gas (LNG) is natural gas which has been artificially condensed into a liquid form by a combination of pressurisation and cryogenic cooling. Liquefaction greatly increases the density of the hydrocarbon allowing it to be stored and transported more efficiently.

Conditions required to condense natural gas depend on its precise composition and the process being used, but typically involve temperatures between −120 and −170 degrees Celsius and pressures of between 150 and 1000 kPa (20 and 150 PSI).

LNG offers an energy density comparable to petrol and diesel fuels, but its cost of production and the need to store it in expensive cryogenic tanks have prevented its widespread use in commercial applications.

Approximately 4% of the U.S. supply of natural gas is imported in the form of LNG.