Offshore Hydrogen: Technically Ready, Moving Toward Scale
Hydrogen production at sea is no longer experimental, and its economics are increasingly viable beyond state support. Locating electrolysis directly at offshore wind sites reduces transmission costs and makes use of low-cost renewable electricity at source. This positions offshore hydrogen as a competitive option even without permanent subsidies. Butendiek Engineering has developed offshore H₂ platform concepts and is now advancing a project into basic and detail design. From electrolyser integration and water treatment to topside layout, marine adaptation, and export systems, the technical elements exist today and can be scaled to multi-megawatt plants. With MW-scale projects operating onshore and first offshore demonstrators underway, the sector is moving toward industrial deployment.
PEM Electrolysis: From Pilots to Large-Scale Modules
Proton-exchange membrane (PEM) electrolysis has matured quickly. Standard 5 MW units and multi-tens-of-MW arrays are in use, with projects at the 20–50 MW scale already delivered. The first 50 MW PEM plants are running onshore, proving the technology at scale. The next step is relocation offshore to connect directly with wind power. Electrolyser projects above 100 MW are in preparation and expected online within the next few years.
PEM technology aligns well with offshore requirements: fast response, wide load range, and high current density allow direct coupling to variable wind generation. Field trials confirm PEM’s ability to operate dynamically, with rapid load changes and start-stop cycling, making it suitable for islanded offshore operation.
Demonstrators at Sea
Initial pilot projects are testing complete systems under real offshore conditions. These demonstrators validate the full chain, from seawater intake and treatment to electrolysis, compression, drying, and export. The focus is not only on “can hydrogen be produced offshore” but on how each subsystem performs together under marine and offshore conditions.
They also address offshore-specific challenges such as corrosion, cyclic loading, HVAC behaviour, hazardous-area zoning, power quality, and maintenance access. Demonstrators are also used to trial new technologies such as advanced membranes, power electronics, and water-treatment methods.
Key Technical Themes for Offshore H₂ Platforms
- Power integration & controls (islanded mode): While PEM stacks can ramp quickly, balance-of-plant (BoP) and power electronics must handle harmonics, flicker, and grid disturbances. Proper control and filtering stabilize operation and reduce stack stress.
- Water treatment: Stack life depends on feedwater quality. Offshore treatment typically follows intake, pre-treatment, fine filtration, and desalination to reach the required purity.
- Electrolyser modules & thermal management: Modular racks with quick connections, closed-loop cooling, and integrated monitoring improve maintainability. At platform scale, gas management, automated purging, and digital twins further support performance and lifetime.
- Compression & export: Options include pipeline export, onboard storage with ship loading, or conversion (e.g. methanol, LOHC) where pipelines are not available. With backbone hydrogen pipelines under planning, compression and grid interface are becoming project-ready.
- Layout & maintainability: Integrated utilities, modular skids, and clear segregation of hazardous areas improve efficiency and safe access for maintenance.
- Reliability under cycling: Dynamic operation improves wind utilization but accelerates wear. Stack lifetime depends on current density, cycling, water purity, and temperature control. Improved stack designs, combined with predictive monitoring, extend operating life.
Supply Chain and Industrial Capacity
European yards and fabricators have decades of experience in offshore oil & gas and wind and are well positioned to build hydrogen platforms. Lessons from offshore wind serial production, such as modularization, takt planning, and digital QA/QC, are directly transferable. The industrial capacity exists today to deliver multi-platform programs.
The real limiting factor is not fabrication or cost-competitiveness: offshore hydrogen can already be produced at prices that make sense for industrial offtakers such as steel producers and refineries, even without permanent subsidies. What is missing is regulatory clarity and infrastructure alignment. Bankable offtake mechanisms, clear timelines for backbone pipelines, seabed permitting frameworks, and harmonized offshore H₂ standards are the keys to unlocking the first large-scale projects. With these in place, offshore hydrogen can follow the same trajectory as offshore wind a decade ago, scaling quickly once commercial conditions are stable.
Our Role
Aqua Consult and Butendiek Engineering GmbH neering, together with partners cruh21 - part of Drees & Sommer , Deutsche Windtechnik AG , ONP Management GmbH , INP Infrastructure GmbH , Impact Funding Europe , and Nordwest Assekuranzmakler GmbH & Co. KG , provide support from concept to operation:
- Concept & FEED: layouts, interface definition, risk studies, and permitting strategies.
- System Integration: controls, BoP packages, water-to-export optimization, digital twins, and lifetime strategies.
- O&M & Risk: exchangeable designs, access concepts, condition-based maintenance, and insurability through suitable risk instruments.
About the Author: Klaas Oltmann , CEO Butendiek Engineering GmbH
With 20 years of experience in offshore engineering and renewable energy, I have had the privilege of leading multiple innovative groundbreaking projects. Our mission to innovate and integrate new technologies continues to drive our efforts in making offshore hydrogen a pivotal element of Europe’s energy strategy.
