Green Hydrogen from Offshore Production: Valves for Use in the North Sea

A million tons of green hydrogen per year, produced in the North Sea and transported to land via pipeline – this is the vision of the AquaVentus initiative, founded in 2020, for the year 2035. With 10 GW of wind energy, the AquaVentus support association and its over 100 members aim to prove through several pioneering projects that offshore electrolysis is possible and can even be an integral part of the future domestic hydrogen supply. This opens up a completely new market for manufacturers of industrial valves. Read here about what the AquaVentus initiative plans and the technical specifications to be considered in offshore electrolysis.

With the publication of the National Hydrogen Strategy (NWS) in June 2020, a long-term government strategy for a single energy carrier was formulated for the first time in the history of the Federal Republic of Germany. In the update of the NWS in July 2023, the federal government explicitly mentioned offshore electrolysis as part of its production target of 10 GW electrolysis capacity by 2030. Almost simultaneously, the long-distance gas network operators published their updated plan for the interregional hydrogen core network on July 15. 

This marks another milestone for offshore electrolysis in Germany, as AquaDuctus is the only offshore pipeline included in the network planning. Designed with a capacity of up to 20 GW, the pipeline could serve as a gateway to North Sea hydrogen. Other neighboring countries would also benefit from this: In addition to Germany, the Netherlands, Denmark, Belgium, Norway, and the United Kingdom also plan to produce large quantities of green hydrogen on or near the North Sea. 

The 1-GW Test Field: The Other Energy Generation Area (SEN-1) 

By 2035, AquaVentus aims to pave the way for the installation of 10 gigawatts of offshore electrolysis here. An important intermediate step is the provision of the "SEN-1" area by the federal government by 2030. The "other energy generation area" is approximately 27.5 km² in size and offers space for nearly 300 MW of installed power generation capacity. Furthermore, the area is intended to provide the consortia gathered in AquaVentus with enough space to implement various "proof-of-concepts" for offshore electrolysis as first movers and early adopters. They hope to gain new knowledge for subsequent follow-up projects, as various exploration concepts must be researched, tested, and their commercial feasibility demonstrated, just like in any industrial revolution. 

In the medium to long term, participants expect a significant cost reduction for offshore hydrogen. The goal is for the energy carrier to become competitive with fossil fuels like gas, oil, and coal in conjunction with a rising CO2 price through the European Emissions Trading Scheme. 

Exploration Concepts and Offshore Electrolyzers 

Two fundamental exploration concepts stand against each other: "integrated electrolysis" and the "central solution." In integrated electrolysis, hydrogen is directly obtained at the wind turbines. The necessary electrolyzers are mounted on platforms attached to the wind turbines.

Additionally, PEM electrolyzers enable higher current densities, allowing a space-saving design of the plants, which is essential for their installation on compact platforms. Moreover, no caustic is used as an electrolyte in PEM electrolyzers – a crucial factor for installation in sensitive environments like the sea. Last but not least, PEM electrolyzers are "black start capable," meaning they can be ramped up and down much faster than alkaline electrolyzers. This is particularly important in times of geopolitical tensions when there is a risk of attacks on critical infrastructure. 

Further Development Necessary 

Regardless of the choice of electrolyzer system, it is important to prepare the seawater pumped from the sea for electrolysis. There are numerous approaches from science and industry for this. Nationally, the lead project H2Mare provides important insights. 

How offshore electrolysis will be further developed technologically also depends on how lawmakers weight individual parameters. In any case, their further development requires government funding, where the corresponding funding regime can have a significant influence on the preferred technology. However, there is no doubt that it is a promising industrial field. If the AquaVentus projects are implemented on schedule, meet high environmental and sustainability standards, and achieve the planned production capacities, they could lay the foundation for a completely new industrial sector. 

The AquaVentus support association, in coordination with its over 100 members, is committed to this goal. The joint goal of a rapid market ramp-up and the safe and system-serving provision of green hydrogen from domestic production has made offshore electrolysis a viable technology for German and European climate protection goals. In the medium to long term, this benefits not only the climate but also an industrial valve sector that has prepared its products for use under the extreme conditions of offshore production. 

Criteria for Industrial Valves in Offshore Use 

The most important requirements for industrial valves in offshore use generally include corrosion resistance. Offshore valves must be made from materials resistant to seawater and other corrosive elements. Stainless steel, special alloys, or corrosion-resistant coatings are often used. 

Additionally, valves must withstand high pressures and extreme temperatures, as they must operate safely and reliably on offshore platforms. Absolute tightness is crucial to avoid leaks that could lead to environmental damage or safety risks. Thus, there is great potential for manufacturers of high-quality seals committed to precise manufacturing methods. 

Due to the difficult accessibility and high costs of maintenance and repair in the offshore sector, valves must also be extremely reliable and durable. They must also meet international standards and certifications, such as API (American Petroleum Institute), NORSOK, or ISO standards, to ensure they meet the specific requirements of the offshore industry. The valves must be robust against mechanical stresses such as vibrations, shocks, and pressure surges, which frequently occur in offshore environments. 

All these requirements apply particularly to offshore electrolysis plants. If you want to learn more about the topic, visit the Valve World Expo in Düsseldorf from December 3-5, 2024. The marine and offshore industry is one of the five main topics there.