A liquefaction plant is a refrigeration works. An import terminal is a pumping station with heaters, and it is the least glamorous and most reliable part of the chain.
Unloading
The ship arrives, moors, and connects to the jetty’s loading arms. The vessel’s own cargo pumps push LNG ashore at something like 10,000 to 12,000 cubic metres an hour.
One detail matters and is easy to miss: as liquid leaves the ship’s tanks, something has to replace the volume or the tanks would collapse under vacuum. A vapour return arm sends gas from the terminal back to the ship for exactly that purpose. Cargo transfer is a two-way operation, and the vapour return line is as necessary as the liquid ones.
Storage
The liquid runs into full containment tanks at close to atmospheric pressure, where it waits. A terminal’s tanks are its buffer between a cargo that arrives in one enormous parcel and a grid that wants gas continuously.
Storage is not passive. The contents boil, age and can stratify, and managing that is a running operational task rather than a matter of building the tank correctly. Storage operations covers what the terminal actually does about it.
The clever bit: pump first, warm second
Here is the part that makes an import terminal efficient, and it is not obvious.
The grid wants gas at high pressure — commonly somewhere around 80 to 100 bar. There are two ways to get there. Vaporise the LNG at low pressure and then compress the gas up to grid pressure, or raise the liquid to grid pressure first and then vaporise it.
Compressing a gas is expensive. Pumping a liquid is cheap, because a liquid is essentially incompressible and the pump is only doing work against pressure, not squeezing anything. The energy difference is very large.
So terminals do it in the second order. Low-pressure in-tank pumps lift the liquid out, high-pressure pumps raise it to pipeline pressure while it is still a liquid at minus 162 degrees, and only then does it meet a vaporiser. The gas leaves the vaporiser already at grid pressure.
The recondenser
Boil-off is a nuisance at a terminal in a way it is not on a ship, because there is no engine to burn it in.
The elegant answer is a recondenser. Boil-off gas is compressed modestly, then brought into direct contact with cold LNG drawn from the tanks on its way to the high-pressure pumps. The cold liquid absorbs the vapour, which condenses back into it, and the combined stream carries on to the pumps.
This turns a problem into free feedstock. The alternative — compressing the boil-off all the way to grid pressure as a gas — costs far more, and terminals fall back on it only when send-out is too low to absorb the vapour.
Unloading is when it matters most: displacing a whole cargo’s worth of vapour back to the ship generates a great deal of boil-off in a short window, and the recondenser is sized for that peak rather than for the average.
Metering, odorising and injection
Before the gas enters the grid it is measured for custody, checked against specification, and odorised — mercaptan added here rather than upstream, because the odorant would freeze in the liquid.
Specification is occasionally a real constraint. A grid with a narrow Wobbe index range will not accept gas that is too rich, and a terminal receiving rich cargoes may inject nitrogen to ballast the heating value down into range.
What it costs
Regasification is the cheap end of the chain, in both capital and energy. Typically one to two per cent of throughput, and close to nothing where seawater does the warming, against eight to twelve per cent consumed liquefying it in the first place.
That asymmetry is worth remembering when reading project economics. An import terminal is a modest investment attached to an enormous one somewhere else.
What the tracker records
The terminal directory lists import terminals with capacity, status, ownership and location, from Global Energy Monitor’s data. Tank count, vaporiser type, send-out rate and berth arrangement are not in the source and render as Not reported rather than being inferred.
For an import terminal the figure that matters commercially is send-out — the rate gas can enter the grid — and where GEM reports capacity for an import terminal, that is what it describes.