August 28, 2025
Decarbonizing shipping remains challenging, as ships are long-lived, capital-intensive assets subject to strict safety regulations, making fuel transitions complex and high-risk, Hanwha Group highlighted in a recent article.
As explained, momentum in alternative fuels however is growing. Fuels like hydrogen and ammonia, already used in other sectors, are starting to gain ground in maritime transport.
#1 Why are alternative fuels like hydrogen and ammonia relevant to shipping now?
The International Maritime Organization has set ambitious decarbonization targets: a 20% reduction in greenhouse gas emissions by 2030, 70% by 2040, and net-zero by 2050 — all relative to 2008 levels. These goals cannot be met through efficiency improvements alone. Lower-emission fuels will be essential.
Hydrogen and ammonia are emerging as leading options because both offer carbon-free tank-to-wake operation and minimal air pollutant emissions. Their relevance is growing amid tightening emissions standards, increased investor scrutiny, and the need to future-proof fleets against rising compliance costs.
#2 What progress is being made in adopting hydrogen and ammonia as marine fuels?
According to Hanwha, hydrogen and ammonia are being introduced into shipping through dual-fuel vessel designs, which offer flexibility as supply chains and bunkering infrastructure develop. Hydrogen is being piloted in smaller vessels such as ferries and tugs, often paired with fuel cells. Ammonia is under evaluation in deep-sea shipping, including bulk and gas carriers.
Furthermore, adoption remains limited, but progress is accelerating, driven by regulatory pressure, advancing technology, and first commercial orders. Dozens of ammonia-fueled ships are under construction or classified as “ammonia-ready.” Engine manufacturers are advancing hydrogen- and ammonia-compatible technologies, with commercial availability expected in the coming years. Interim class rules and regulatory frameworks are also improving approval pathways.
While no oceangoing vessels currently operate on hydrogen or ammonia alone, the technical and regulatory groundwork is steadily taking shape.
#3 What safety challenges do hydrogen and ammonia present at sea?
Hydrogen and ammonia introduce distinct safety risks that require new approaches in containment, vessel design, and crew preparedness.
Hydrogen is highly flammable, with a high leak risk and low ignition energy. It must be stored at cryogenic temperatures or high pressure, raising challenges around structural integrity, boil-off gas management, and fire prevention.
Ammonia is less flammable, but highly toxic. Even small leaks can be hazardous, requiring robust ventilation, controlled bunkering operations, and clearly designed escape routes. It is also corrosive and can degrade certain materials over time.
Both fuels demand marine-specific containment systems, rigorous design standards, and specialized training — particularly at sea, where space is limited and response windows are short.
#4 What does successful adoption of hydrogen and ammonia require?
Scaling hydrogen and ammonia adoption at sea will require regulatory clarity, mature technology, ship design integration, and skilled crews — all underpinned by early collaboration across the industry.
Regulation is a critical factor: hydrogen- and ammonia-fueled vessels are not yet covered by the IMO’s IGF Code, which applies only to natural gas. Until at least 2028, they must be approved through a risk-based Alternative Design Approval (ADA) process, requiring proof of safety equivalence to conventional ships. Class societies such as DNV have issued their own rules, which, if accepted by regulators, can help streamline approval.
Meeting these future regulations will also demand changes in vessel design. Ships must accommodate the fuels’ lower energy density, often requiring larger tanks and more complex integration. Safety systems — including detection, ventilation, and emergency venting — must be designed specifically for maritime use.
Crew readiness is equally critical. Seafarers will need new skills to safely operate and maintain these systems, and to respond to emergencies. Until IMO standards are finalized, custom training programs, developed in coordination with Flag States and class societies, will be essential.
While interim guidance is supporting early projects, long-term clarity on regulations will be vital for widespread adoption.
