Ship-to-ship ammonia transfer can be safe and practicable, provided that recommended safeguards and operational controls are implemented, the Global Centre for Maritime Decarbonisation has said.
The Centre has based its comments upon lessons learned from a pilot project carried out in September last year.
Landmark trial
A pilot project on the ship-to-ship transfer of liquid ammonia between two gas carriers, the Green Pioneer and the Navigator Global, took place 20 nautical miles offshore from Port Dampier, in the Pilbara, last September.
“The location was strategically chosen for its operational advantages, including an existing ammonia terminal, longstanding expertise in ammonia handling, a dedicated large anchorage, and a safe distance from shore,” the Centre said.
The trial looked at lightering and simulated bunkering operations, transferring 2,700 metric tonnes (MT) of liquid ammonia at a rate of 700-800 cubic metres per hour (m³/hr).
Safety studies were structured around four key areas: feasibility, risks, consequences, and response. Findings across all four areas confirmed that ship-to-ship ammonia transfer at anchorage can be both safe and practicable.
“The safety studies provided quantitative insights into the operational limits and emergency preparedness for this trial, forming a reference for future pilots and commercial-scale operations,” the Centre said.
Computational Fluid Dynamics (CFD) plume dispersion modelling was conducted to evaluate potential ammonia release scenarios, simulating a release of 33 m³ ammonia.
“At a wind speed of 10 m/s, [Computational Fluid Dynamics] results showed that a 33 m3 release on the deck of the ship would produce a plume of up to 40 metres tall, 60 metres wide and 750 metres long. Within the dedicated anchorage boundary of 1 NM (1,852 metres), such a release is unlikely to pose safety risks or operational disruption to vessels at adjacent anchorage points. Hazard Identification (HAZID) and Hazard and Operability Study (HAZOP) highlighted 23 medium-level risks specific to the trial that were mitigated through the implementation of additional controls, like the use of Emergency Release Couplings (ERC), avoiding simultaneous operations (SIMOPS), and stationing a standby incident response vessel,” the Centre said, adding that emergency response includes specification of communication protocols, a personal protective equipment matrix, the appointment of an incident handler, verification of onboard spill kits, and the deployment of a firefighting tugboat.
Professor Lynn Loo, CEO of the Centre, said, “In the past, bunkering guidelines took years to develop and were typically derived from experience with actual operations.
In this case, guideline development is preceding actual commercial-scale operations, making it all the more important that these trials are as informative and comprehensive as possible so they can serve as a relevant reference for industry bodies in refining safe handling procedures, emergency response plans, and operational guidelines”.
The Centre notes that the first two-stroke dual-fuelled ammonia engine is expected to be operational early next year and that the IMO’s approved the world’s first global emission pricing framework tied greenhouse gas intensities in April this year.
Further reading
“Path to zero-carbon shipping, insights from ammonia transfer trial in the Pilbara”, the Global Centre for Maritime Decarbonisation, June 2025.
