The Global Centre for Maritime Decarbonisation (GCMD) has released a comprehensive report detailing the learnings from a pioneering pilot successfully completed in September 2024, involving the ship-to-ship transfer of liquid ammonia between two gas carriers.
The vessels involved were the Green Pioneer and the Navigator Global, and the pilot was conducted at the Western Anchorage WA19, 20 naut mile from Port Dampier in Pilbara, Western Australia. The trial showcased lightering and simulated bunkering operations, transferring 2,700t of liquid ammonia at a rate of 700-800m3/hr. The location was strategically chosen for its operational advantages, including an existing ammonia terminal, longstanding experience in ammonia handling, a dedicated large anchorage, and a safe distance from shore.
Titled Path to zero-carbon shipping, insights from ammonia transfer trial in the Pilbara, the report outlines how the trial specifically addressed technical, logistical, safety, and regulatory requirements associated with ammonia transfer within an operating port’s anchorage.
Comprehensive 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, provided that recommended safeguards and operational controls are implemented. 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.
To establish the allowable weather envelope for safe ammonia transfer operations for this trial, a mooring analysis was conducted, referencing prior LNG bunkering operations. This analysis, which evaluated 36 different sea states, concluded that safe operations are possible up to a maximum wind speed of 20 knots and a swell height of 0.3m. These conditions are well within the weather threshold required to prevent bridge wing collisions.
Computational fluid dynamics (CFD) plume dispersion modelling was conducted to evaluate potential ammonia release scenarios. A conservative approach was taken, simulating a release of 33m³ ammonia, corresponding to four times the volume of the most credible worst-case scenario. At a wind speed of 10 m/s, CFD results showed that a 33m3 release on the deck of the ship would produce a plume of up to 40m tall, 60m wide and 750m long. Within the dedicated anchorage boundary of 1,852m, 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 (ERCs), avoiding simultaneous operations (Simops), and stationing a standby incident response vessel. These findings form a basis that future bunkering operations can adapt and build upon.
Emergency response measures included specification of communication protocols, a personal protective equipment (PPE) matrix, the appointment of an incident handler, verification of onboard spill kits, and the deployment of a firefighting tugboat. Vessel crews also conducted ammonia-specific emergency drills to reinforce readiness.
The report documents the operational aspects of the trial, detailing the transfer systems, shutdown arrangements, and a timeline of key events.
GCMD says that development of ammonia propulsion systems has accelerated, with the first two-stroke dual-fuelled ammonia engine expected to be operational early in 2026. IMO’s approval of the first global emissions pricing framework tied to GHG fuel intensities in April 2025 is likely to further position ammonia as a viable zero-carbon fuel for shipping. In light of these developments, GCMD is continuing its collaboration with industry partners to close safety, technical and operational gaps with real vessels and in front-running ports.
Prof Lynn Loo, CEO, GCMD, 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.”
