LNG is natural gas from which most of the impurities such as sulphur and
carbon dioxide have been removed. It is cooled to or near its boiling point of
–165°C at or near atmospheric pressure and is transported in this form as predominantly
liquid methane. Methane has a critical temperature of –82.5°C, i.e. the
pressure and temperature above which liquification cannot occur, so that
methane can only be liquefied by pressure at very low temperatures.