Finnish ship designer Deltamarin has teamed up with Gaztransport & Technigaz (GTT), an engineering company specializing in membrane containment systems for transport and storage of LNG, on providing LNG solutions for a portfolio of vessels embarking on long ocean voyages.
The portfolio includes a container vessel, a pure car and truck carrier (PCTC) and a cruise ship, and it has been created with an aim of saving valuable cargo space compared to classic cylindrical-type LNG tank solutions, as explained by Deltamarin.
During the development project, each of the vessels was equipped with a modularised GTT membrane tank type solution, which can be adjusted in size from 1,000 to 5,000 cbm, depending on the case vessel. Either one or multiple tanks can be integrated into the vessel. The final fuel capacity is a trade-off between desired cargo capacity and bunkering intervals, the ship designer said.
As an example, a containership case vessel with a 2,500 cbm tank offers an autonomy time of 22 days or can reach 10,000 nautical miles. These figures ensure that most intra-Asian, intra-European or intra-American trade loops can be sailed in just one bunkering operation.
Naturally, other sizes offering the same volume efficiency but less cargo space sacrificed are available, for example 1,000 cbm, 1,500 cbm or 2,000 cbm. Similar scalable solutions exist for the PCTC and the cruise ship.
On average, calculations during the development project showed that only approximately 60 pct of the LNG capacity provided by membrane technology could be accommodated in the same space, when using an optimised bi-lobe C-type tank solution. For large fuel capacities, therefore, the membrane solution is clearly the most feasible LNG fuel tank solution, Deltamarin said.
According to Deltamarin’s calculations, the option is better from a financial perspective as well. A financial scenario calculation was carried out with the following input parameters in which distillates (MGO) has been defined as a reference level:
As the figures indicate, in this case the LNG membrane tank solution pays itself back in less than 3 years compared to the reference level, whereas HFO with the scrubber option offers slightly shorter payback time.
“From a Net Percent Value (NPV) point of view, the LNG membrane solution offers the highest value of all options over the ten-year period. This is due to the savings made by both, in LNG fuel price and efficient use of hull volume for LNG fuel tanks,” Deltamarin added.
As highlighted, compared to Type-C tank solution, a significant amount of valuable cargo space inside the hull can be saved. The HFO option also has moderate fuel costs but is penalised because of the extra power and sludge handling required by the scrubber operation. With the fuel price scenario used, operating with MGO almost doubles the operating cost over 10 years compared to LNG options.