Natural gas is the main source of energy. Liquefied natural gas or LNG is natural gas that has been converted to a liquid form to facilitate storage or transportation by cooling the natural gas to approximately -162 ° C. It is then stored at atmospheric pressure. Liquefied natural gas occupies about six hundredths of the volume of natural gas in the gaseous state. It is odorless, colorless, non-toxic and non-corrosive. As it is easy to transport, LNG can be used to save natural gas deposits for which pipeline construction is uneconomical.


Liquefaction of natural gas into LNG requires cooling of the natural gas until it becomes liquid. These processes include gas treatment prior to liquefaction, processing and control of impurities and liquid hydrocarbons, as well as storage and handling of refrigerants used to cool natural gas to a liquid state. Liquefaction also has the advantage of removing oxygen, carbon dioxide, sulfur and water from natural gas, leading to LNG, which is almost pure methane.

The refrigerants used in the LNG process usually consist of a combination of the following light hydrocarbons: methane, ethane, ethylene, propane, butane and isopentane. Nitrogen is also a common refrigerant.

The liquefaction process requires significant refrigeration compression systems, which include large centrifugal compressors typically driven by gas turbines, steam turbines or large electric motors.

When the LNG reaches its destination, it returns to the regasification plant. LNG (methane) vapors mixed with air are not explosive in an uncontaminated environment. In the case of a large release of LNG, a fire could occur, but only if a concentration (5 to 15%) of LNG vapor in the air and a source of ignition is present.