Liquefied Natural Gas: A Breakdown of How We Make and Move Liquid Energy

Liquefied Natural Gas (LNG) is the consolidated, more transportable form of the natural gas that we use to generate energy and heat. Natural gas, mainly formed of methane and including other trace gasses, is cleaned and cooled, ready for transport. Here’s a simple breakdown of how natural gas transforms into LNG and why.

Sourcing Natural Gas:

Natural gas is produced as a bi-product of oil production (petroleum oil hydrocarbons), wherein a well is produced in the earth and, using a pump, oil is brought to the surface. In doing so, natural gas is extracted; and in some cases in absence of the necessary infrastructure, the gas is burnt off in the contentious practice of production flaring which unnecessarily releases carbon into the atmosphere. 

Where possible, natural gas is piped directly to consumer, but how do we transport LNG to consumers not within the reach of appropriate piping and infrastructure?

Liquefaction:

In order to transport large volumes of natural gas, it must first be liquefied so as to shrink the space necessary to contain it; this is achieved by sharply cooling the gas to -162C. 

Before this however, gravity and solvents are used to strip the gas of its impurities; like H2O, CO2 and H2S, which would freeze during the liquefaction process. Then, remaining gasses like propane are removed and thus remains methane and trace ethane. 

Natural gasses passes through a coolant which shrinks the gasses volume by around 600 times. In this state, LNG is non-toxic and appears much like water.

Transport:

After the point of liquefaction, LNG can be passed onto insulated and cooled vessels on various modes of transport like boats and trucks. Once the LNG reaches its destination, the liquid is returned to its liquid temperature and stored until use. 

Safety Concerns and Environmental Impact:

One of the direct hazards when processing cold liquids is the embrittlement of associated equipment. When pipes, flange joints, gaskets and infrastructure comes in contact with extreme colds they can become brittle, and therefore more susceptible to cracks and breaks. This makes for a considerable risk of gaseous spray and ignition; similarly these cold gasses can cause freeze burns with contact to skin. Where embrittlement is difficult to mitigate, gas sprayout can be mitigated simply by use of effective safety shield, such as Sureband.