Fraunhofer ISE Harnesses Seawater to Produce Hydrogen Using PEM Electrolyzer

Scientists at the Fraunhofer Institute for Solar Energy Systems ISE have developed a technical concept and design for a hydrogen generation plant optimized for use at sea, called the “OffsH2ore” project.

The project aims to define an economically and technically optimized design for an integrated offshore hydrogen production plant using proton exchange membrane (PEM) electrolysis, including transporting the compressed hydrogen gas to land.

The OffsH2ore project guarantees hydrogen production without territorial competition, offering a promising path to a carbon-neutral future. The project is funded by the German Federal Ministry for Economic Affairs and Climate Protection and includes Fraunhofer ISE, PNE AG, SILICA Verfahrenstechnik GmbH, KONGSTEIN GmbH, and Wystrach GmbH.

The power supply for the PEM electrolysis comes from an offshore wind farm that is directly connected to a 500 MW electrolysis platform. The platform can produce up to 50,000 tons of green hydrogen per year. Freshwater for the PEM electrolyzer is obtained by desalinating seawater using residual heat from electrolysis.

The produced hydrogen is purified and dried, compressed to 500 bar, and transferred to a transport vessel that can carry up to 400 tons of hydrogen from the platform to the mainland. This concept is independent of the hydrogen transport pipeline and offers flexibility in the choice of location.

According to Marius Holst, the project coordinator, “Offshore hydrogen production offers the opportunity to cover the entire value chain at the national level while decoupling the expansion of offshore wind energy and the expansion of the grid.”

To determine the costs of hydrogen production, the first step was to determine the cost-optimal capacity of the offshore wind farm based on the electrolysis capacity of 500 MW. The minimum hydrogen production costs result from wind power of 602 MW. In this case, they amount to 5.92 EUR/kg with just under 5,000 full charge hours of electrolysis.

Hydrogen production costs increase and full charge hours decrease with lower wind capacity. For example, a wind farm with a capacity of 490 MW results in hydrogen production costs of €6.37 ($7.04)/kg and full load hours of around 4,225 h/a. As a result of the lower wind capacity, the 500 MW electrolysis is significantly oversized and can no longer operate at a nominal load.

“The results show that the production of hydrogen directly in the sea with a PEM electrolyzer is technically and economically feasible,” explained the scientists involved in the project. “With the concept presented by the consortium, rapid and large-scale implementation is realistic.”

This project offers a promising path to a carbon-neutral future by using offshore wind energy and seawater as resources for hydrogen production. The concept provides flexibility in the choice of location and guarantees hydrogen production without territorial competition. The project offers a glimpse into the potential of offshore hydrogen production and its role in decarbonizing the energy sector.