Ammonia dual-fuel ships will be best positioned to meet the International Maritime Organisation's (IMO) Net-Zero Framework from 2028 onwards, according to a study by University College London (UCL) and maritime consultancy UMAS.
The study says LNG-fuelled ships will benefit from the IMO's rules in the short term, but they will no longer comply after 2030 unless operators switch to bio-LNG or install onboard carbon capture and storage (CCS) systems. Without CCS, they will not generate enough surplus units (SUs) to offset emissions.
Uncertainty around future LNG prices and abatement costs could also limit its appeal as a long-term bunker fuel, the study said.
In contrast, blue ammonia ships will remain compliant until the mid-2040s. After that, vessels would need to switch to e-ammonia to avoid buying remedial units. Methanol dual-fuel ships would need to transition from biomethanol to biodiesel by 2034, and to e-methanol by 2038 to stay within IMO limits.
Fuel choice will be shaped by abatement and penalty costs until the mid-2030s, but emissions intensity will become the main driver after that, the study said.
UCL and UMAS used total cost of operation modelling to compare LNG, methanol, ammonia and conventional bunker fuels. The model also factored in potential gains from SUs discussed at the IMO's Marine Environment Protection Committee (MEPC 83), although final SU values may still change.
On the port side, the study said infrastructure investment will follow shipowner demand. In the near term, ports should support at least three bunker fuels, but in the medium term, they should focus on ammonia.
