While they may look the same, standard-sized LNG carriers and small-scale LNG carriers live very different economic and operational lives, writes Small Scale LNG Shipping director Eduardo Perez Orue
LNG carriers are like whales: majestic massive creatures that cross the oceans. People look at them from a distance and wonder how they are possible.
Continuing with the analogy, I will say that small-scale LNG carriers in all their variations are like sardines. Let’s compare them from several points of view.
Standard LNG carriers are shipping wonders able to carry between 100,000 to 266,000 m3 of LNG. To do that, they use containment systems mostly based on membrane or Moss technologies. Without entering in too many technical details, they are single-product carrying ships that do one thing and do it well.
Conversely, small-scale LNG carriers, those below 40,000 m3 in size, are more flexible and generally use different technologies altogether. Most new small LNG carriers have IMO Type-C tanks that allow them to potentially carry other products over time. They are multi-gas carriers. In fact, about one seventh of today’s small-scale LNG carriers transport products other than LNG, mostly ethane and ethylene but sometimes LPG, butadiene, propylene and other compatible cargoes. They do it to maximise the earning potential of the ships over time, because unlike their bigger cousins, when the LNG market is struggling to provide employment, these small ships can go to any other compatible trade and make a decent earning loading other cargoes instead of sitting and waiting for the next available LNG cargo.
Apart from the technology used for the tanks, the size of standard and small LNG carriers sets them apart. The biggest LNG carriers can reach up to 345 m in length overall, while most small LNG ships are below 100 m. Pioneer Knudsen, for instance, is only 69 m long.
When it comes to propulsion, each ship type’s engine technology is different, too. While standard-sized ships focus on using boil off gas (BOG) as fuel, smaller vessels are more interested in flexibility. Therefore, the use of dual or even triple-fuel engines allows them to burn natural gas, ethane or fuel oil and gives them the flexibility to navigate to areas where LNG bunkering is non-existent or expensive.
Finally, the way these two ship classes handle BOG is also different, with small LNG carriers incorporating mini-reliquefaction plants on board that allow them to reduce BOG waste to a minimum.
The flexibility of most new small LNG carriers is clear: a small LNG carrier today might be transporting ethane tomorrow and move to LNG bunkering later in its life.
While they are both called the same (LNG carriers) and both look similar, please do not think of small LNG carriers as simply smaller LNG carriers. They are much more than that. Just like whales and sardines, they may look very similar and navigate the same waters, but are completely different animals with different behaviours, serving different markets and with very different economic profiles.
Small LNG carriers are neither better nor worse than standard LNG carriers; they are different ships that solve a different problem. Therefore, they need to be managed differently.
