In March 2024, a converted offshore supply vessel called the Fortescue Green Pioneer completed a seven-week trial burning ammonia instead of oil in the waters off Singapore. The Maritime and Port Authority of Singapore (MPA) confirmed the demonstration and called it a world first for ammonia used as a marine fuel in one of the planet’s busiest ports.
Now, more than two years later, the trial stands as a landmark moment in a shipping industry racing to meet the International Maritime Organization’s target of net-zero greenhouse gas emissions by or around 2050. Shipping accounts for roughly 3% of global CO₂ emissions, and the sector has few proven alternatives to the heavy fuel oil that has powered it for over a century.
What the trial actually tested
The Fortescue Green Pioneer was not a new build. It was a retrofitted vessel, which made the demonstration more relevant to the existing global fleet of roughly 100,000 commercial ships. During the seven-week trial, five interconnected systems were put through operational testing: ammonia storage tanks, the piping network, a gas fuel delivery system, retrofitted engines, and the vessel’s overall seaworthiness.
That integration matters. Previous ammonia engine research, including work by manufacturers like MAN Energy Solutions and Wärtsilä, had largely focused on combustion performance in controlled laboratory or test-bed settings. The Singapore trial required every component to function together aboard a crewed vessel operating under real port safety protocols, surrounded by commercial traffic.
“This is the difference between proving you can burn ammonia and proving you can run a ship on it,” said a maritime energy analyst familiar with the trial’s scope, summarizing the industry’s view of the demonstration’s significance.
Singapore’s regulator had to approve the vessel’s operations before it could enter port waters, including how the ammonia systems were installed and managed. That sign-off indicates baseline safety and technical standards were met, though the MPA has not published detailed pass-or-fail results for individual components or disclosed whether modifications were required during the trial.
The ammonia challenge: toxicity, cost, and color
Ammonia presents hazards that conventional marine fuel does not. It is acutely toxic at relatively low concentrations, and a leak in an enclosed engine room could be fatal within minutes. The trial presumably operated under strict safety measures, but no detailed incident reports or crew safety assessments have been made public.
Then there is the carbon question. Ammonia contains no carbon, so burning it produces no CO₂ at the exhaust stack. But how the ammonia itself is produced determines whether the fuel is truly zero-carbon. Most ammonia today is made from natural gas through a process that generates significant CO₂ emissions. This product is sometimes called “grey ammonia.” Only ammonia produced using renewable electricity to split water into hydrogen, which is then combined with nitrogen, qualifies as “green ammonia” with a near-zero lifecycle carbon footprint.
The MPA’s published accounts do not specify which type of ammonia the Fortescue Green Pioneer burned. Fortescue, the Australian mining and energy company behind the vessel, has invested heavily in green hydrogen and ammonia production as part of its broader energy strategy, but the company’s commercial interest in promoting ammonia as a fuel means its public statements should be weighed separately from the regulator’s factual confirmation.
Ammonia also carries less energy per unit of volume than conventional marine fuel, meaning ships would need larger fuel tanks or more frequent refueling stops. That practical constraint adds cost and complexity that the seven-week trial, conducted in a single port, did not need to confront.
Where ammonia fits among rival fuels
Ammonia is not the only alternative fuel vying to replace oil in global shipping. Methanol has moved faster toward commercial adoption. Danish shipping giant Maersk took delivery of its first methanol-capable container ship in 2023 and has ordered more than a dozen additional vessels designed to run on the fuel. Liquefied natural gas, or LNG, is already used on hundreds of ships, though it still produces CO₂ and carries methane slip risks that undercut its climate benefits.
Green hydrogen is another candidate, but storing it requires either extreme compression or cryogenic temperatures, making it impractical for long ocean voyages with current technology. Ammonia, which is easier to store as a liquid and already traded globally as a fertilizer feedstock, offers a logistical advantage over hydrogen, even if its toxicity and engine compatibility challenges are more severe.
No single fuel has emerged as the clear winner. The IMO’s revised greenhouse gas strategy, adopted in July 2023, set interim targets for 2030 and 2040 but did not mandate a specific fuel pathway, leaving the industry to sort out which alternatives can scale fastest and most affordably.
What has happened since
Singapore has continued to position itself as a hub for alternative marine fuels. The MPA’s net-zero shipping agenda frames the Fortescue Green Pioneer trial as one element of a broader bunkering and decarbonization program. The city-state already dominates conventional ship refueling and aims to extend that advantage to green fuels as international emissions rules tighten.
Globally, ammonia bunkering infrastructure remains sparse. Most major ports have no facilities for loading ammonia as a marine fuel. Building the supply chain, from renewable energy generation to electrolyzers, nitrogen separation plants, and port-side storage, requires investment on a scale that a single demonstration voyage cannot unlock.
Classification societies, flag states, and port authorities across multiple jurisdictions will also need to agree on design codes, crew training requirements, emergency response procedures, and inspection regimes before ammonia-fueled ships can operate on international routes. The Fortescue Green Pioneer trial offers a data point, but not yet a regulatory template.
What this means for shipping’s future
The practical takeaway from the trial is narrow but real. One vessel demonstrated that ammonia storage, piping, fuel delivery, and retrofitted engines can operate together at sea under port authority supervision without disqualifying safety failures, at least over a limited period in a single port’s waters.
What remains to be proven is whether ammonia can meet the shipping industry’s economic, environmental, and operational demands at scale. Detailed performance data from the trial, including thermal efficiency, power output, and fuel consumption figures, have not been released publicly. Without those numbers, independent analysts cannot calculate ammonia’s cost penalty relative to heavy fuel oil or project when the economics might tip in its favor.
The Fortescue Green Pioneer should be understood as a proof of concept: important, and encouraging for zero-carbon shipping advocates, but still one early chapter in a much longer effort to wean the world’s fleets off fossil fuel.
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*This article was researched with the help of AI, with human editors creating the final content.
