An LNG carrier has burned its own cargo since the beginning, out of necessity. Ships that are not LNG carriers burning LNG on purpose is a much newer thing, and it has grown a supply chain of its own that looks almost nothing like the LNG trade.
Why shipowners chose it
Regulation, principally. Sulphur limits on marine fuel, tightened globally and tightened further inside emission control areas, left owners choosing between expensive low-sulphur distillate, exhaust scrubbers, or a different fuel.
LNG answers the local pollution question comprehensively. Burning it produces essentially no sulphur oxides, almost no particulates, and substantially less nitrogen oxide than a conventional marine engine. For a vessel spending much of its life in controlled waters, that is a straightforward case.
The greenhouse case is a different argument, addressed below, and it is genuinely unresolved.
Three ways to deliver it
Ship to ship, from a dedicated bunker vessel typically holding a few thousand cubic metres. This is how large vessels are fuelled, and it is a ship-to-ship transfer with the same fenders, linked shutdown systems and weather limits as any other, just smaller. It can happen while the receiving ship works cargo, which is what makes it commercially viable.
Truck to ship, from road tankers on the quay. Simple, needs no marine asset, and limited by how many tanker loads anyone wants to sequence — practical for small vessels and low volumes.
Shore to ship, by pipeline from a terminal to a berth. Efficient where it exists, and it exists in few places, because it requires a terminal to have built for a business that may not arrive.
Why it is a different business
LNG trade moves enormous parcels infrequently between a small number of counterparties on long contracts. Bunkering moves small parcels frequently to whoever is in port, on terms closer to a fuel sale than a commodity contract.
That changes the asset base entirely. Bunker vessels are small-scale ships, often using Type C pressure tanks rather than membranes, because at that size a pressure vessel is affordable and it tolerates the boil-off of an intermittent duty without needing a handling system.
It also changes the risk. A bunker supplier holds inventory against demand it cannot forecast precisely, in a fuel that will not sit still, for customers who may switch back to oil if the price spread closes.
The chicken and egg
Bunkering infrastructure and gas-fuelled ships are each pointless without the other, and neither is cheap.
Owners will not order gas-fuelled tonnage without confidence they can refuel where they trade. Ports will not build supply for ships that do not yet call. The deadlock broke where a large operator committed to a fleet and a supply chain simultaneously, or where a port with LNG import capacity already had liquid available and could add small-scale distribution to an existing terminal.
That last route explains the geographic pattern: bunkering capability has largely appeared at places that already had a reason to hold LNG.
Methane slip decides the emissions argument
This is the part that matters and the part most often glossed over.
Burning methane produces less carbon dioxide per unit of energy than burning fuel oil, so combustion arithmetic favours LNG. But methane released unburned is a far more potent greenhouse gas than the carbon dioxide it would have become, and gas engines release some.
How much depends on the engine, and the difference between engine types is large rather than marginal. Lean premixed Otto-cycle engines — the dual-fuel medium-speed machines common in the bunkering market — slip the most, because a premixed charge sits in crevices where the flame cannot reach it. High-pressure diffusion-cycle engines slip far less, because the gas arrives after compression and burns where it is injected.
So “does LNG reduce emissions” has no single answer. It depends on the machinery, on the leakage upstream of the ship, and on whether you weight methane over twenty years or a hundred. Anyone quoting a confident figure should be asked which engine and which time horizon they assumed.
What the tracker holds
Bunkering infrastructure is not in the Global Gas Infrastructure Tracker as a category, and it is not on this site. Import terminals that also serve small-scale distribution appear as import terminals.
The carrier directory would be where bunker vessels appeared, and it is empty until GEM’s LNG Carrier Tracker is loaded — which, as the carriers page explains, requires someone to download it by hand.