Within the framework of the joint research project ProHyGen, the Institute for Fluid Dynamics and Ship Theory (FDS) at the Hamburg University of Technology (TUHH) is developing a self-sufficient floating offshore H₂ generator for the integrated production and storage of green hydrogen in remote sea areas, which have so far been unutilized. The Friedrich-Alexander Universität Erlangen-Nürnberg (FAU) and the companies CRUSE Offshore GmbH and RENK GmbH are working together on the research project. Associated partners are H&R GmbH & Co.KGaA., Hamburg, Korean Register Co, Busan, and HanmiGlobal Co, Ltd, Seoul. The TUHH is the coordinator of the research project. The project is funded by the Federal Ministry for Economic Affairs and Climate Protection from the Climate and Transformation Fund.

The ongoing global efforts to reduce greenhouse gas emissions mean that in the future a significant increase in demand for hydrogen based on renewable energies, i.e. green hydrogen, must be expected. At the same time, current generation capacities are very limited, as the supply of industry and consumers with electrical energy from renewable sources must be realised in parallel. To meet this challenge, a floating hydrogen generation unit (Figure1) for sea areas outside the potential sites for conventional offshore wind farms will be developed to prototype stage. A wind turbine generates the energy to produce the hydrogen from desalinated seawater on the floating platform. An innovative method for unpressurized storage of hydrogen based on a liquid organic hydrogen carrier (LOHC) enables non-hazardous transportation using slightly modified conventional tankers. This self-sufficient integrated facility for the production and storage of green hydrogen does not compete for space with other energy production methods and offers cost advantages over the production of hydrogen from other renewable energy sources.

At TUHH, the wind turbine platform is being optimised in terms of its hydrostatic and hydrodynamic behaviour. Of particular interest in the investigation is the displacement of the LOHC between the tanks, which can have an influence on the motion of the entire turbine. The dynamic behaviour of the total system will also be investigated under extreme weather conditions and the influence of possible collision events. Numerical models will be developed to simulate the flow on the wind turbine and the floating structure and to calculate the unsteady aero- and hydrodynamic forces on the system and its components during the LOHC loading and unloading process. During the refuelling process with LOHC, rapid changes in the floating position may occur, under which the plant must continue to operate.

The plant will be scaled up to 15 MW nominal power. Results will also include evaluation and optimization of the LOHC hydrogenation reactor performance on the floating platform.LOHC technology allows the existing logistics of the oil industry, tankers, tank barges, tank farms and stations to be used at lower hazard class standards. The hydrogen-rich LOHC is hardly flammable and non-explosive. On land, the hydrogen is separated from the LOHC again and is available as pure hydrogen, Figure 2

The system is to be used in areas with high wind potential, so that the integrated wind turbine will be able to ensure the constant availability of renewable electricity, see Figure 3. The required quantities of water are provided with the help of a seawater desalination plant and the waste heat of the elctrolysis/LOHC process.

Grid connection and large transformer platforms are not necessary for the use of the plant. The floating hydrogen production unit is merely anchored to the seabed with conventional anchor lines, which minimises the impact on the environment. The concept is highly scalable: the number of units set up depends on the suitable sea areas available and, if deployed worldwide, would be technically capable of cost-effectively supplying much of the demand for green hydrogen.

As the concept is independent of water depth and proximity to the coast, offshore locations with considerably higher energy density can be developed.

The ProHyGen project pursues the following goals, among others:

• Development of a complete plant design for the production of hydrogen, bonding to a LOHC and refuelling of tankers.
• Completion of the necessary planning documents for the production of the 5 MW prototype of the hydrogen generation unit in the German EEZ.
• Scaling of the prototype to a nominal power of 15 MW
• Development of a hydrogen farm layout for a European location and planning of the logistics for transport to the hydrogen metropolis of Hamburg, see Figure 4.