Additional costs to enable very large crude carrier (VLCC) to run on LNG rather than conventional fuel are about $20m, with around $2m extra needed at the newbuilding stage to make the vessel ready for a future retrofit to ammonia, class society DNV has estimated.
In a joint industry project, DNV and its partners TotalEnergies, Samsung Heavy Industries, and a major Asian energy shipping company investigated the rationale of ammonia as a future fuel for a new LNG dual-fuel VLCC tanker design and the business cases for converting the vessel to ammonia.
The study found five key considerations for conversion and retrofit from dual-fuel LNG to dual-fuel ammonia on a vessel designed to be ammonia-ready. Namely, the LNG fuel gas supply system must be replaced entirely. Modifications are also necessary to the tank system, main engine, safety systems, gensets, and boilers.
For an ammonia-ready newbuild, the design arrangements must account for both LNG and ammonia. According to DNV, the energy density of ammonia is considerably lower than that of LNG, almost half in terms of volume, limiting vessel autonomy and calling for a bunkering strategy to be reassessed. In the study, the most cost-effective compliance strategy in all cases was to operate on LNG with increasing amounts of bio-LNG blended in, as the required conversion technology is not fully available.
The study looked into a VLCC design with a lifespan of 20 years, assumed to operate on the Middle East to Far East Asia route from 2024 at a speed of 13 knots.
In related news, DNV has been selected to lead an ammonia bunkering safety study by the Global Centre for Maritime Decarbonisation (GCMD) in Singapore. The study will be carried out in partnership with Surbana Jurong and the Singapore Maritime Academy (SMA) and aims to define a set of safety guidelines and operational envelopes that will establish the basis of a regulatory sandbox for ammonia bunkering trials in Singapore.