Lhyfe’s offshore hydrogen production pilot aces trials

French hydrogen producer Lhyfe has shared operating results from its Sealhyfe project, also known as the world’s first offshore hydrogen production pilot which returned to dock in November 2023, confirming that the initial objectives were met.

Courtesy of Lhyfe

Lhyfe launched the Sealhyfe project, equipped with a 1 MW electrolyzer supplied by Plug, on September 23, 2022, in Saint-Nazaire to prove the technical feasibility of such a project and acquire the operational experience needed to scale up quickly.

A range of measurement and data collection instruments were installed on board Sealhyfe to ensure precise management and control of all the production unit’s parameters from September 2022 to November 2023, first at the quayside and then at sea.

The platform, which is capable of producing up to 400 kilograms of hydrogen a day, began producing its first kilograms of offshore hydrogen on June 20, 2023.

After 14 months of testing, the platform was brought back to the Quai des Frégates in Saint-Nazaire with its full production capacity intact.


During this trial period, Sealhyfe tested the system’s versatility and responsiveness in various configurations. The experiment also confirmed the system’s ability to manage the variability of wind power in specific offshore conditions. The electrolysis system was operated as part of the planned research tests, including at maximum production capacity. The performance achieved was as high as on land, confirming the reliability of the installation, Lhyfe reported.

Lyhfe also noted that Sealhyfe was confronted with five significant storms, including Ciaran, which swept along the Atlantic coast in October 2023, with waves over 10 meters high and winds of over 150 kph. A complete analysis of the production system once it was back on land confirmed that all equipment had returned unharmed with its production capacity intact.

Throughout the experiment, on-board and remotely controlled measuring instruments were used to identify ways of optimizing the efficiency and reliability of Lhyfe’s production units.

The quayside benchmark testing phase helped to de-risk the project. According to Lhyfe, the site was operated exclusively remotely from Lhyfe’s control center, using supervision and control tools specifically developed by the company. The experiment made it possible to validate the software and algorithms for producing green and renewable hydrogen and to reduce the number of operations required in the marine environment. In total, Lhyfe carried out fewer than ten maintenance operations and the system was operated for 70% of the operating time.

What is more, as part of this world first, Lhyfe also worked with the French authorities to define the operating rules for a green hydrogen production unit operating within an urban, industrial, and port environment, and also capable of operating in the open sea.  

Next steps

As the next step, the results of this experiment are already being incorporated into the HOPE project, which represents the second stage in Lhyfe’s offshore ambitions.

The HOPE project, which is coordinated by Lhyfe as part of a nine-partner consortium, was selected by the European Commission (EC) under the European Clean Hydrogen Partnership for a €20 million grant. From 2026, this large-scale 10 MW project will be able to produce up to four tonnes a day of green hydrogen at sea, which will be exported ashore by pipeline, and then compressed and delivered to customers.

Building on the results from the Sealhyfe project, Lhyfe also aims to ensure that the production processes at and-based sites are reliable and optimized from the outset so that they can be ramped up quickly and progressively.

The company’s ambition is to have a production capacity of up to 22 tonnes of green hydrogen per day by the end of 2024 and up to 80 tonnes per day by 2026.

Matthieu Guesné, Founder and CEO of Lhyfe, said: “The positive results of the Sealhyfe trial and the lessons we have learned from it represent a major new step for Lhyfe. We can now draw on our experience of three onshore sites and one offshore site to design our next green hydrogen production sites. This bolsters our expertise and the confidence of our partners, and supports the entire industry, because Sealhyfe has made offshore hydrogen production a reality”.