Production of e-fuels directly on the high seas

11.07.2025

Source: E & M powernews

The "H2Mare" hydrogen project is testing a platform for the production of e-fuels at sea in Bremerhaven. Offshore deployment off Helgoland is planned from July 2025.

The hydrogen lead project H2 Mare is testing a floating plant for the production of synthetic fuels under real offshore conditions in Bremerhaven. The platform represents a complete Power-to-X process chain for the first time - from hydrogen production to e-fuel synthesis, according to the Federal Ministry of Education and Research.

The Karlsruhe Institute of Technology (KIT), the German Aerospace Center (DLR) and the Technical University of Berlin jointly developed the 60 x 15 meter platform. They designed the system in container format and made it storm and seaworthy. Following its construction in the port of Bremerhaven, the consortium plans to test the system off the island of Helgoland from July 2025.

The research team will produce green hydrogen directly on board the platform by splitting desalinated seawater into hydrogen and oxygen using high-temperature electrolysis. The platform uses only electricity from renewable sources, which will come directly from offshore wind turbines in a later expansion stage.

However, hydrogen alone is not sufficient for the production of synthetic fuels. This is why an integrated direct air capture system is used, which filters the required carbon dioxide (CO2) directly from the ambient air. The two components - hydrogen and CO2 - serve as starting materials for the production of a synthesis gas, which chemically consists of carbon monoxide and hydrogen.

The system then feeds this gas into a reactor in which the so-called Fischer-Tropsch synthesis takes place. Under controlled conditions, liquid hydrocarbons are produced that can be further processed into synthetic kerosene or diesel.

Prof. Roland Dittmeyer, Head of the Institute of Micro Process Engineering at KIT and coordinator of the "PtX-Wind" sub-project, wants to use the platform to run through all the steps - from technical implementation to operation - under offshore conditions. The project team is developing concepts for larger production platforms on this basis. It is also analyzing the resilience of the materials, the dynamics of the processes with fluctuating energy supply and the regulatory requirements at sea.

The consortium aims to deliver reliable results by the end of 2025. Its aim is to link large-scale platforms with offshore wind farms in order to produce green hydrogen and its downstream products where the energy is generated - without any detours via the power grid.

In addition to the Fischer-Tropsch synthesis, H2 Mare is investigating other Power-to-X routes. A trial to produce liquid methane will soon begin at the KIT Energy Lab in Karlsruhe. At the same time, the project team is working on concepts for the production of methanol and ammonia.

Background: Power-to-X products store surplus renewable energy, serve as climate-neutral fuels or as basic materials in industrial processes. H2Mare focuses on so-called derivatives from offshore hydrogen and develops decentralized, grid-independent processes for this purpose.

The Federal Ministry of Research, Technology and Space (BMFTR) is funding H2Mare as part of the national hydrogen flagship projects. Its aim is to create the technical basis for the economic use of green hydrogen - especially in applications that are difficult to electrify, such as aviation, shipping and the raw materials industry.

Author: Davina Spohn