Explore ammonia’s role in maritime decarbonization—covering storage risks, engine compatibility, real-world use, and future trends in this comprehensive guide.
In the evolving maritime industry, ammonia is gaining prominence as a promising alternative marine fuel. As global regulations tighten around carbon emissions and the quest for decarbonization intensifies, ammonia stands out for its potential to eliminate CO₂ emissions at combustion. Yet its introduction comes with unique challenges—toxicity, infrastructure gaps, and regulatory hurdles. This article delves into ammonia’s role in maritime operations, exploring why it matters, the latest technological and regulatory developments, practical challenges and mitigation strategies, real-world applications, and the path ahead.
Why This Topic Matters in Maritime Operations
Shipping contributes around 3% of global GHG emissions, projected to rise to 5–8% by 2050 unless action is taken The IMO’s decarbonization strategy includes net-zero emissions by 2050 and proposed GHG intensity targets, alongside carbon pricing mechanisms set to take effect by 2028 . Within this context, ammonia—especially green or e-ammonia—emerges as a zero-carbon combustion candidate, capable of enabling deep-sea decarbonization.
Ammonia offers high volumetric energy density at ambient conditions and can be a hydrogen carrier, making it more practical than liquefied hydrogen for maritime fuel logistics . The IEA forecasts ammonia could meet about 45% of shipping fuel demand by 2050 As such, its strategic importance as a clean fuel alternative cannot be overstated.
Key Developments, Innovations, or Technologies
Regulatory Advances and Interim Guidelines
In December 2024, the IMO’s Maritime Safety Committee approved interim guidelines for ammonia as a marine fuel, addressing safety and reliability comparable to conventional systems These guidelines complement amendments to both the IGF Code and IGC Code, enabling ammonia use on vessels and bunkering operations, with entry into force expected July 1, 2026, and voluntary uptake encouraged earlier B. Class societies and the STCW Convention are also being updated to ensure crew training and operational readiness
Engine Compatibility and Innovations
2025 is a breakthrough year: the first ammonia-fuelled marine engines are being delivered, with a surge of orders anticipated as expertise grows Wärtsilä (now Everllence) has achieved over 1,000 operating hours safely on ammonia engines, with successful dual-fuel Otto-cycle designs available commercially Additionally, studies confirm viability of dual-fuel marine diesel engines using ammonia alongside diesel, hydrogen, or LNG
Port Readiness and Bunkering Trials
The Port of Rotterdam executed a successful ship-to-ship ammonia bunkering trial in April 2025, transferring 500 tonnes of grey ammonia under strict safety protocols with zero emissions Singapore and other major ports are also preparing pilots and infrastructure for ammonia bunkering by 2027
Cost, Fuel Economics, and Dual-Fuel Pathways
As of early 2025, green ammonia costs ranged from US$885–1,050 per ton, compared to US$500–600 per ton for heavy fuel oil, translating to a US$1,400–1,650 cost gap per ton of HFO equivalent Modeling shows that LNG–ammonia dual-fuel vessels offer the most cost-effective operational profile until the mid-2030s, with standalone ammonia becoming cheapest from around 2037 onwards
Challenges and Practical Solutions
Toxicity, Corrosiveness, and Safety Risks
Ammonia is highly toxic; exposure above 2,000 ppm can be fatal within 30 minutes, and contact can injure skin and eyes severely. A Singapore pilot identified over 400 risks related to bunkering—leaks, toxic dispersions, material compatibility—and emphasized the need for emergency-response protocols. The Safety Handbook and other guidelines stress use of double containment, leak detection, automated isolation, and crew training as mitigation strategies
Full Lifecycle Emissions and Air Quality
Although combustion of ammonia emits no CO₂, it can release NOₓ, N₂O, and ammonia slip—all of which contribute to climate forcing and degrade air quality. N₂O has a GWP of 273 over 120 years Production methods (gray vs. blue vs. green ammonia) significantly affect lifecycle emissions, making well-to-wake assessments critical
Infrastructure Gaps
Unlike LNG, ammonia bunkering infrastructure remains scarce. As of 2024, only 25 ammonia dual-fuel ships were on order globally, compared to hundreds for LNG and methanol fuelsLimited supply chains and high costs make scaling a formidable challenge
Operational Uncertainties and Market Hesitancy
Shipping stakeholders cite regulatory inertia, toxicity concerns, and supply insecurity as key deterrents. Despite trials, only two small ammonia-powered vessels are currently active . The complexity of deploying novel technologies across fleets continues to slow adoption.
Case Studies / Real-World Applications
Amogy’s Ammonia-Fuelled Tugboat
In New York, a 67-year-old tugboat was retrofitted to operate on renewably produced ammonia, which is split into hydrogen and nitrogen to power an electric fuel cell—achieving zero-emissions propulsion. The project, backed by US$220 million in funding and collaborations with shipbuilders like HD Hyundai, demonstrates real-world feasibility of clean ammonia use .
Fortescue’s Green Pioneer
The Green Pioneer ammonia-diesel hybrid ship docked in London ahead of the Terra Carta Summit. Fortescue converted two of four engines to run on ammonia blends, aiming for zero terrestrial emissions by 2030. The vessel’s trials underscore industry leadership and the call for regulatory and infrastructural readiness worldwide .
Port of Rotterdam Bunkering Pilot
In April 2025, Rotterdam executed a ship-to-ship ammonia bunkering of 500 tonnes with zero emissions—signaling maturity in operational readiness and a leap toward scalable ammonia supply chains .
Future Outlook & Trends
Scaling Ammonia and Fuel Mix Evolution
Dual-fuel (LNG–ammonia) vessels will dominate until mid-2030s, then pure ammonia becomes cost-effective. By 2050, ammonia could account for 25–45% of maritime fuel mix, per industry forecasts .
Regulatory Momentum
IMO’s GHG intensity standards and mandatory carbon pricing by 2028 will further incentivize low or zero-carbon fuels. Finalizing the IGC/IGF amendments by 2026 will allow formal ammonia operations under SOLAS, and STCW training updates will ready crews from the mid‑2020s .
Technology and Safety Innovations
Manufacturers like Everllence (formerly Wärtsilä) and others continue to develop safe, reliable ammonia engines. Safety protocols, bunkering guidelines, and crew training programs are rapidly maturing .
Infrastructure Investment
Ports like Rotterdam and Singapore are investing in ammonia readiness; Rotterdam has completed trials, and Singapore aims for operational bunkering in 2027 . Scaling supply chains and bunkering networks remains essential.
FAQ Section
1. Why is ammonia considered a “sustainable” marine fuel?
Ammonia burns without CO₂ emissions. If produced as green ammonia (via renewable energy), it can achieve near-zero lifecycle emissions and meet net-zero goals .
2. What are the main storage and safety challenges?
Ammonia is toxic and corrosive. Exposure risks and bunkering leaks necessitate robust safety systems, training, and equipment design (double barriers, detection, isolation systems) .
3. When will ammonia-fuelled ships start operating?
The first engines are being delivered in 2025, with operation trials underway. Early vessels and bunkering trials are already in progress, particularly in Rotterdam and pilot projects globally .
4. How does ammonia compare cost-wise to conventional fuels?
Currently, green ammonia costs 2–3 times more than heavy fuel oil. However, cost parity may emerge between 2030–2035 with scaling and carbon pricing .
5. What role does regulation play in ammonia adoption?
Crucially. IMO guidelines, IGC and IGF Code amendments effective by 2026, and crew certification updates via STCW are foundational for safe and legal deployment .
6. Can ammonia replace other fuels soon?
Ammonia’s adoption will likely begin with dual-fuel systems, gradually shifting from LNG or methanol pathways toward more widespread ammonia use by the late 2030s .
7. Are there successful real-world ammonia applications?
Yes—examples include Amogy’s ammonia-powered tugboat and Fortescue’s Green Pioneer hybrid vessel, plus Rotterdam’s bunkering trials showcase practical implementation A.
Conclusion
Ammonia is not just a speculative fuel—it is rapidly transitioning into a tangible, strategic element of maritime decarbonization. With regulatory pathways in motion, engine technologies maturing, and pilot projects underway, the fuel is poised to reshape the industry. Challenges around safety, cost, and infrastructure remain—but so do solutions emerging from those very challenges. Vessel owners, port authorities, and maritime stakeholders should invest in ammonia readiness now—embracing dual-fuel strategies, updating regulations, and building bunkering infrastructure—positioning for a low-carbon shipping future.
Call to Action: Engage with ongoing trials, collaborate with classification societies, and support policy frameworks that scale ammonia use responsibly. Together, the maritime sector can chart a decarbonized course—on ammonia’s promising horizon.
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