LNG is a type of liquefied gas, meaning that LNGs are components of natural gas that are separated from the gas as liquids. More specifically, an LNG is a natural gas that has been processed to remove valuable elements and compounds such as helium and impurities like carbon dioxide and hydrogen sulfide and then condensed into liquid by cooling.An LNG is made predominately of methane (CH4) with some mixture of ethane (C2H6) and other trace compounds. Table 2.1 shows the chemical composition and other physical properties of a standard LNG.