Maritime transport of hydrogen and its carriers, such as ammonia and liquid organic hydrogen carriers (LOHCs), is subject to a complex regulatory framework involving international conventions, classification society rules, and port state controls. These regulations aim to ensure safety, environmental protection, and operational efficiency while addressing the unique challenges posed by hydrogen and its derivatives.
The International Maritime Organization (IMO) plays a central role in regulating hydrogen transport through the International Code of Safety for Ships Using Gases or Other Low-Flashpoint Fuels (IGF Code). The IGF Code, adopted in 2015 and amended in subsequent years, provides mandatory standards for ships using low-flashpoint fuels, including hydrogen and ammonia. It covers design, construction, and operational requirements, such as fuel containment systems, ventilation, fire safety, and crew training. The IGF Code is part of the Safety of Life at Sea (SOLAS) Convention, making it binding for signatory states.
For ammonia, the IGF Code addresses its toxicity and flammability risks, requiring gas detection systems, emergency shutdown procedures, and double-walled piping. However, the code’s provisions for liquid hydrogen (LH2) are less comprehensive, reflecting the limited commercial deployment of LH2 in maritime applications. Future amendments are expected to expand LH2-specific guidelines as the technology matures.
Classification societies, such as DNV and Lloyd’s Register (LR), supplement the IGF Code with detailed technical standards. DNV’s rules for gas-fueled ships include additional requirements for hydrogen and ammonia, such as material compatibility testing, risk assessments, and leak detection systems. LR’s guidelines emphasize cryogenic storage solutions for LH2 and stress the need for robust safety barriers to prevent hydrogen embrittlement in ship structures. Both societies actively collaborate with industry stakeholders to refine their standards as new data becomes available.
Port state control (PSC) regimes enforce compliance with international and national regulations during ship inspections. The Paris and Tokyo Memoranda of Understanding (MoUs) are key PSC frameworks that authorize inspections of ships carrying hydrogen or its carriers. Inspectors verify adherence to the IGF Code, check safety equipment functionality, and review crew certification. Non-compliance can result in detention, fines, or operational restrictions. Some ports have additional local regulations; for example, the European Union’s Net-Zero Industry Act includes provisions for hydrogen import terminals, requiring environmental impact assessments and emergency response plans.
Despite these frameworks, regulatory gaps persist. The IGF Code does not fully address LOHCs, which are chemically distinct from pure hydrogen or ammonia. LOHCs require specific handling procedures due to their organic composition and potential decomposition risks. Additionally, international standards for hydrogen leakage monitoring during ship operations are underdeveloped, posing challenges for emissions tracking.
Another gap is the lack of harmonized bunkering regulations. Hydrogen and ammonia bunkering protocols vary across jurisdictions, creating operational inefficiencies. The IMO is working on unified guidelines, but progress is slow due to differing national priorities. For instance, Japan and South Korea, both leaders in hydrogen shipping, have developed their own bunkering standards, while the EU favors a regional approach under the Alternative Fuels Infrastructure Regulation (AFIR).
Future regulatory needs include expanding the IGF Code to cover emerging hydrogen carriers like LOHCs and methylcyclohexane (MCH). Enhanced leak detection standards and real-time monitoring technologies should be prioritized to mitigate climate risks, as hydrogen leakage can indirectly contribute to global warming. International collaboration is also needed to establish uniform bunkering protocols and training programs for crews handling hydrogen-based fuels.
The IMO’s revised Greenhouse Gas (GHG) strategy, aiming for net-zero emissions by 2050, will likely influence hydrogen shipping regulations. Potential measures include carbon intensity benchmarks for hydrogen-derived fuels and incentives for zero-emission vessels. However, the strategy’s implementation depends on consensus among member states, which may delay binding measures.
In summary, maritime transport of hydrogen and its carriers is governed by a mix of international, classification society, and port state regulations. While the IGF Code provides a foundational safety framework, gaps remain in addressing LOHCs, bunkering standards, and leakage monitoring. Future regulatory developments must prioritize harmonization, technological adaptation, and climate considerations to support the safe and scalable deployment of hydrogen in global shipping.