The five steps
The LNG chain has five links, and a cargo passes through all of them between a gas field and a burner tip.
Production and treatment. Gas comes out of a field mixed with water, carbon dioxide, hydrogen sulphide, mercury and heavier hydrocarbons. Almost all of that has to go before liquefaction. At minus 162 degrees, water and carbon dioxide are solids: a trace of either would build up as ice inside the heat exchangers and block them. Mercury attacks the aluminium those exchangers are made from. So the first stage of any liquefaction plant is a chemical works that dries and sweetens the gas until it is almost pure methane with a controlled amount of ethane and propane.
Liquefaction. The treated gas is chilled in stages against circulating refrigerants until it condenses. One complete refrigeration line is called a train, and a large one produces roughly 5 to 8 million tonnes a year. This is where most of the capital cost sits and where the technology is most concentrated: a small number of firms license the process, and fewer still can build the cryogenic heat exchangers at its centre. Our liquefaction explainer goes through the cycles in detail.
Storage and loading. Liquid is held at the terminal in insulated tanks, typically full containment designs with an inner tank of nickel steel and an outer concrete wall that could hold the contents if the inner one failed. When a ship arrives, pumps move the cargo aboard through insulated loading arms in roughly twelve to eighteen hours.
Shipping. An LNG carrier is a floating vacuum flask with an engine that can burn what evaporates. Between 145,000 and 174,000 cubic metres is the standard size today, with a few Q-Max vessels at 266,000. The cargo is not refrigerated in transit on most ships. It stays cold because the tanks are well insulated and because a small amount is continuously allowed to boil, which carries heat away in the same way sweat cools skin.
Regasification. At the receiving end the liquid is pumped up to pipeline pressure and warmed back into gas, either at an onshore terminal or aboard a moored ship called an FSRU. Seawater is the usual heat source. From there it enters the grid like any other gas.
Why the cold is the whole problem
Everything difficult about LNG follows from one number. Methane boils at minus 161.5 degrees Celsius at atmospheric pressure. That is colder than anything in ordinary industry, and it dictates the materials: ordinary carbon steel becomes brittle and shatters, so tanks and pipework use nickel steels, stainless steel, aluminium or specialised alloys such as Invar. It dictates the insulation, because every watt of heat that leaks in boils off cargo. And it dictates the safety design, because a spill of liquid at that temperature flash-boils into a vapour cloud.
It also explains why the chain has so few suppliers. Welding a membrane a millimetre thick that has to stay leak-tight through hundreds of thermal cycles is not something a general fabricator picks up quickly. The same is true of coil-wound heat exchangers, of cryogenic submerged pumps, and of the yards that can build a carrier. Each of those is a short list, which is the subject of our supplier pages.
Where the energy goes
Liquefaction is not free. Chilling and compressing the gas consumes roughly 8 to 12 per cent of the energy in the gas itself, most of it burned in the gas turbines that drive the refrigerant compressors. Shipping adds a few per cent more, and regasification a little on top. A rough rule is that delivering LNG across an ocean costs around 10 to 15 per cent of the energy delivered, before any accounting for methane leakage.
That is also why electrification matters commercially and not just environmentally. If the compressors are driven by electric motors rather than gas turbines, and the electricity is low-carbon, the plant’s own emissions fall sharply. Several plants under construction are built this way, and it is one of the reasons the equipment lists on new projects look different from those of a decade ago.
What the numbers mean
Capacity gets quoted in three different units depending on who is speaking, which causes endless confusion. Producers talk in million tonnes per annum, pipeline operators in billion cubic metres a year of gas, and ship people in cubic metres of liquid. One million tonnes a year is about 1.36 billion cubic metres of gas a year. One cubic metre of liquid is about 600 cubic metres of gas. A standard 174,000 cubic metre cargo is roughly 78,000 tonnes of LNG. We keep both terminal units side by side on every page, and there is a conversions explainer if you need to move between them.
The parts that are hard to replace
Reading the chain end to end, three links stand out as genuinely hard to substitute at short notice.
The first is the liquefaction train, because of the process licence and the heat exchangers. The second is cargo containment, because the membrane systems used by most of the modern fleet are licensed by a very small number of firms. The third is the ships, because there are only a handful of yards in the world that can build one, and their slots are booked years ahead. Everything else in the chain, from the pipeline that feeds the plant to the pumps that unload it, has more suppliers and shorter lead times.
That is the reason this site is organised the way it is: an asset directory built from public tracker data, and beside it a short, source-cited list of the firms behind those three links.