The UK’s Maritime and Coastguard Agency (MCA) has released new guidance on the use of ammonia as a marine fuel, marking a ‘vital’ step toward enabling wider alternative fuel adoption in the country’s shipping industry.
As disclosed, the guidelines, issued on April 16, 2025, provide a framework for operators, shipbuilders, as well as classification societies looking to develop or retrofit vessels powered by ammonia, a zero-carbon but highly toxic and flammable fuel.
More specifically, the MCA has noted that the document offers insight into how shipowners can seek a stamp of approval for the operations of ships that run on ammonia, primarily through the International Maritime Organization’s (IMO) alternative design arrangement (ADA)—a risk-based design process catered under SOLAS, which identifies and mitigates the main hazards associated with a vessel’s operation.
As informed, for ships above 500 gross tonnes, the Maritime and Coastguard Agency at present regulates those units carrying ammonia as cargo under the IMO’s International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (the IGC Code). For units under 500 GT, there is a case-by-case approval system.
It is understood that the MCA has worked together with operators and classification societies to regulate ships using ammonia under the IMO’s interim guidelines published as part of the International Code of Safety for Ships Using Gases or Other Low-flashpoint Fuels (IGF Code).
The agency said that it is also collaborating with other IMO member states to refine the guidelines, with the goal of incorporating them into the IGF Code in the future, following reviews. As representatives from the UK government agency elaborated, the IGF Code necessitates an alternative design arrangement to be submitted to the administration.
In terms of ammonia, in particular, the MCA’s brand-new guidance has placed responsibility on the shipowner, stipulating that owners and operators of vessels must ensure that the ammonia-fueled systems are as safe as conventional ones. This includes recommendations to perform regular risk assessments, craft mitigation strategies and submit full technical documentation for review.
What is more, the MCA has highlighted the “urgency” of making sure that crew members are properly trained to handle ammonia. As noted, crew training for alternative low-flashpoint fuels—ammonia among them—is currently governed by the IGF Code training requirements under the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW).
The MCA shared that it has been collaborating with training providers to roll out a dedicated methanol course for convention-sized vessels, with initial courses planned for the middle of this year. Meanwhile, basic ammonia fuel training is set to formally be introduced into the UK’s maritime curriculum starting in September 2025.
To remind, in a February 2025 report, Lloyd’s Register Maritime Decarbonisation Hub (The Decarb Hub) and the Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping (MMMCZCS) reiterated the ‘significance’ of using ammonia as a marine fuel, but also underscored that the industry was facing a ‘tremendous’ workforce challenge pertaining to the handling of this clean energy source.
Namely, the partners’ report found that as many as 800,000 workers need to be upskilled to deal with the unique hazards associated with handling ammonia and ammonia-powered vessels, such as toxicity, flammability, explosions and material incompatibility.
To facilitate a bump-free transition to ammonia-powered operations, the MMMCZCS and the Decarb Hub recommended that regulators and flag states revise global training standards, shipowners and operators perform internal analyses and upgrade corporate policies, seafarers seek upskilling opportunities and training providers to organize competency-based training modules with practical safety drills.