Offshore hydrogen production presents a unique opportunity to leverage nuclear energy in the form of small modular reactors (SMRs) or floating nuclear power plants. These systems can provide the high temperatures and stable energy output required for efficient hydrogen generation through thermochemical water splitting or high-temperature electrolysis. Unlike land-based nuclear plants, offshore installations offer advantages such as proximity to water resources, reduced land use conflicts, and potential integration with desalination processes. However, they also introduce distinct challenges in safety, regulation, and infrastructure.

Small modular reactors are designed for scalability and flexibility, making them well-suited for offshore deployment. Their compact size allows for factory fabrication and transportation to remote locations, including floating platforms. When coupled with thermochemical cycles such as the sulfur-iodine (S-I) or hybrid sulfur processes, SMRs can achieve high efficiencies in hydrogen production. These cycles require temperatures above 750°C, which advanced SMR designs can deliver. Alternatively, high-temperature steam electrolysis (HTSE) operates at around 700–900°C, reducing electrical energy demand compared to conventional low-temperature electrolysis. Offshore nuclear plants can thus produce hydrogen with lower carbon emissions than fossil fuel-based methods while avoiding intermittency issues associated with renewables.

Floating nuclear plants, a subset of offshore SMRs, are self-contained units mounted on marine vessels or platforms. Russia’s Akademik Lomonosov, the world’s first floating nuclear power plant, demonstrates the feasibility of such systems for remote energy supply. Adapting this model for hydrogen production would involve integrating thermochemical or electrolytic processes directly onto the platform. The abundance of seawater simplifies feedstock access, but desalination is necessary to produce high-purity water for electrolysis or thermochemical cycles. This creates a synergy where waste heat from the reactor drives desalination, improving overall system efficiency.

Safety protocols for offshore nuclear hydrogen production must address both nuclear and hydrogen-specific risks. Marine environments introduce challenges such as saltwater corrosion, wave-induced stresses, and potential collisions. Multiple passive safety systems, including gravity-driven cooling and containment structures resistant to extreme weather, are essential. Hydrogen handling requires leak detection systems, explosion-proof equipment, and ventilation to prevent accumulation in confined spaces. International maritime regulations, such as those enforced by the International Maritime Organization (IMO), would govern these installations alongside nuclear safety standards from the International Atomic Energy Agency (IAEA).

Regulatory hurdles are more complex for offshore nuclear projects than for land-based equivalents. Jurisdictional ambiguities arise when plants operate in international waters or exclusive economic zones. Licensing involves coordination between nuclear, maritime, and environmental agencies, often across multiple countries. The lack of precedent for floating nuclear hydrogen facilities further complicates approvals. By contrast, land-based nuclear hydrogen projects benefit from established regulatory frameworks and existing infrastructure for grid connectivity and hydrogen distribution. However, they face opposition due to land use and cooling water requirements.

A key advantage of offshore systems is their potential to co-produce fresh water through desalination. Nuclear reactors provide a steady heat source for multi-effect distillation (MED) or reverse osmosis (RO) systems. This dual-output capability is particularly valuable in arid coastal regions where water scarcity limits conventional hydrogen production. For example, a 300 MW SMR could desalinate approximately 100,000 cubic meters of water daily while generating hydrogen, supporting both industrial and municipal needs.

Land-based nuclear hydrogen projects, such as those proposed in the U.S. Department of Energy’s H2@Scale initiative, focus on large-scale centralized production. These benefit from existing nuclear plants and pipeline networks but are constrained by geographical and political factors. Offshore systems, while more flexible in siting, require significant investment in marine infrastructure, including specialized vessels for maintenance and hydrogen transport. Costs for floating nuclear plants are higher initially but may be offset by reduced transmission losses and avoided land acquisition expenses.

Material compatibility is another critical consideration. Offshore environments accelerate degradation of structural and storage materials. Advanced coatings and corrosion-resistant alloys are necessary for reactor components, hydrogen pipelines, and storage tanks. Hydrogen embrittlement risks are heightened in marine settings, demanding rigorous material testing and monitoring.

The economic viability of offshore nuclear hydrogen depends on scale and location. Remote areas with high energy costs or limited renewables may find these systems competitive. In regions with cheap natural gas or abundant solar/wind, land-based electrolysis remains more cost-effective. However, as carbon pricing expands and hydrogen demand grows, offshore nuclear could fill a niche for low-carbon, high-volume production.

Future developments may see hybrid systems combining offshore wind, nuclear, and hydrogen storage. Floating wind turbines could supply electricity for low-temperature electrolysis, while SMRs provide heat for thermochemical processes. Such integration would maximize resource use and grid stability. Pilot projects, like those explored by Japan and South Korea, will be crucial in demonstrating technical and economic feasibility.

In summary, offshore nuclear hydrogen production offers a promising but challenging pathway for decarbonization. Its success hinges on overcoming regulatory, safety, and cost barriers while capitalizing on synergies with desalination and renewable energy. Land-based projects provide a more straightforward route in the near term, but offshore solutions could unlock new opportunities for global hydrogen trade and sustainable water-energy systems.