Liquefied natural gas (LNG) is essentially a methane gas mixture that has been cooled to the point that it becomes a liquid. At atmospheric pressure, this phase transition happens at around −162 °C thus making it a cryogenic liquid.
LNG has a density of around 430 kg/m³ to 480 kg/m³ and a gross calorific value of around 54 MJ/kg to 56 MJ/kg depending on the composition. It is easily transportable by means of an LNG road tanker (having a typical capacity of around 19000 kg), making it a very practical fuel in areas where gas pipelines are scarce, and no real gas infrastructure exists.
LNG is typically stored in large cryogenic vessels that are designed using the principles of a vacuum or Dewar flask. Such vessels are super-insulated to help minimise the amount of boil-off into the atmosphere. At this point, the fuel can either be dispensed as LNG, or it can be vaporised into its gaseous state.
Typical applications of LNG include serving as a fuel depot, fuel for LNG vehicles, or once vaporised, used for industrial heaters or burners, or alternatively, domestic distribution.