The decarbonisation of maritime transport hinges on the availability of scalable zero-emission fuels. Among the various candidates, methanol and ammonia have emerged as leading options, each progressing along different but converging trajectories. Methanol has already surpassed proof of concept and is entering initial commercial deployment, while ammonia is approaching proof of concept, supported by accelerating engine development, safety research, and bunkering trials.
This study, produced by the Global Maritime Forum, evaluates the technical maturity of both fuels, the challenges of scaling their supply chains, and the practical barriers to adoption. Its findings highlight not only the technical feasibility of these fuels but also the systemic challenges in infrastructure, fuel availability, and regulatory frameworks that must be addressed if shipping is to align with decarbonisation targets by 2030.
Methanol: A Practical but Supply-Constrained Solution
Methanol has quickly moved beyond pilot demonstrations into real-world operations. By mid-2025, around 60 methanol-capable ships are in service, with more than 300 on order and bunkering available at over 40 ports.
Technological and Operational Readiness
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Methanol’s liquid state at ambient temperature and pressure makes it relatively simple to handle compared to other alternatives.
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Engines, tanks, and supply systems are already commercially available, though teething problems with engine components and spare parts persist.
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Retrofits are proving technically feasible and cost-competitive versus LNG or ammonia retrofits, though capacity in suitable shipyards and high upfront CAPEX remain hurdles.
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Operational Considerations
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Bunkering operations are similar to conventional fuel oil and can be conducted using adapted bunker barges, facilitating early adoption.
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Safety risks are moderate, requiring specific but manageable adaptations in venting and firefighting.
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Crew training is relatively short and has scaled up quickly after initial bottlenecks.
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The Bottleneck: Green Methanol Supply
The limiting factor is not technology but fuel. Most ships still rely on grey methanol, with small volumes of bio-methanol and only the first e-methanol deliveries taking place in 2025. While global project announcements suggest up to 40 Mt of future supply, only a fraction has reached final investment decision. Long-term offtake agreements, price premiums, and certification uncertainties remain major obstacles.
Ammonia: Technical Complexity and Safety Challenges
Ammonia, in contrast, remains earlier in its adoption curve but is progressing rapidly. Over 40 ammonia-capable ships are on order, primarily LPG/ammonia carriers and bulk carriers, with Wärtsilä and WinGD leading in engine development.
Safety and Design Requirements
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Ammonia’s toxicity requires significant vessel redesigns: segregated zones, double-wall piping, extensive detection systems, and emergency shutdown protocols.
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Crew training is more demanding than for methanol, with seafarers showing mixed reactions but gradually gaining confidence through training programs in Asia and Europe.
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Emission Performance
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Engine tests indicate potential for 90–95% tank-to-wake emissions reductions, exceeding early expectations. However, concerns remain over nitrous oxide emissions and ammonia slip, both of which could undermine climate benefits if not tightly controlled.
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Operators plan gradual adoption, often running vessels on ammonia only part of the time during early deployment phases.
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Bunkering: The Weakest Link
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Bunkering trials have been completed at several major ports, but ship-to-ship operations are not yet established.
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Infrastructure investment is lagging, and knowledge levels vary widely across ports. Dedicated ammonia bunker vessels may be required sooner than initially assumed.
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Scaling the Fuel Supply Chain: Policy and Collaboration Imperatives
The report identifies fuel availability as the central barrier to both methanol and ammonia adoption. For methanol, the task is scaling cost-competitive green production; for ammonia, it is ensuring safe, standardized bunkering infrastructure.
Key recommendations include:
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Policy incentives to bridge cost gaps and support early movers.
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Harmonised certification schemes to validate emissions reductions and build investor confidence.
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CAPEX grants and demand aggregation mechanisms to accelerate bunkering infrastructure deployment.
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Knowledge-sharing platforms and collaborative port initiatives to standardize safety practices and accelerate operational learning.
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From Feasibility to Systemic Deployment
The transition of methanol and ammonia from pilot fuels to practical decarbonisation pathways illustrates both the opportunities and complexities of shipping’s energy shift. Methanol offers near-term scalability and manageable technical barriers but is constrained by insufficient supply of truly green molecules. Ammonia holds the promise of deeper emissions reductions but faces formidable design, safety, and infrastructure challenges.
Both fuels are technically viable today—but neither will scale without decisive policy action, harmonized certification, and sustained investment across the value chain. The next five years will determine whether shipping achieves the “tipping point” of 5% zero-emission fuel use by 2030. What is clear from the study is that the time of pilots is ending: systemic solutions for supply, safety, and market alignment are now urgently required.
Source: GLOBAL MARITIME FORUM, August 2025 “From pilots to practice: Methanol and ammonia as shipping fuels”
