Lhyfe to re-oxygenate the oceans via offshore hydrogen production

Hydrogen offshore Lhyfe

Lhyfe, the French company based in Nantes, sees enormous potential in producing hydrogen offshore. This is the reason why it is working on this through its Sealhyfe platform. At the same time, the company founded by Matthieu Guesné wants to help re-oxygenate the oceans.

Lhyfe and hydrogen offshore

Seawater and wind: these are the ingredients that Lhyfe came up with in 2017 to produce renewable hydrogen and decarbonise transport and industry on a massive scale. The vision has now become a reality with Sealhyfe (see our article). This pilot site can produce up to 400 kg of hydrogen a day off the Atlantic coast of Saint-Nazaire. The platform was launched in the second half of 2022. Lhyfe is also involved in the project HOPE (Hydrogen Offshore Production for Europe). The latter aims to produce up to 4 tonnes of hydrogen a day at sea, off the coast of Ostend in Belgium, by 2026.

What is less well known is that Lhyfe also wants to inject the oxygen co-produced during the water electrolysis into aquatic environments. Work began in June 2020 with several research bodies, including the Research Institute for Development (IRD)* in Brest. It is a project that the company hopes to materialise one day, while deploying future offshore production platforms.

Returning oxygen from electrolysis

50% of the oxygen on Earth comes from the oceans. It was produced by marine cyanobacteria, and began to accumulate in the Earth’s atmosphere and shallow waters 2.5 billion years ago. This oxygen is essential for fishing and the marine ecosystem. Yet oxygen levels in the sea have been falling since the 1950s. And the phenomenon could accelerate as a result of global warming and increasing pollution levels. There is an urgent need to act, because the oceans are warming up and, in the process, losing their capacity to absorb GHG.**

Lhyfe explains that producing 1 kg of green hydrogen by electrolysis of water generates 8 kg of oxygen. The aim is to return this oxygen to the ocean to support its resilience. But first we need to study the impact of artificial reoxygenation. This is why a study was carried out with experts in physical and biogeochemical modelling of the oceans at the IRD in Brest. Lhyfe fully funded this work.

Defining a scientific and legal basis

The simulation shows the impact of industrial oxygen injection at sea. However, at this stage there are major disparities, with a 25% increase in zones with minimum oxygen in the Bay of Bengal, for example, while there is a 30% contraction in the Atlantic and North Pacific (a phenomenon linked to the physical transport of this oxygen). These results call for a cautious approach.

Lhyfe’s ambition is therefore to provide a sufficient scientific, legal and technological basis to pave the way for the effective implementation of ocean reoxygenation, alongside future industrial sites for the production of green hydrogen.

*IRD: Institut de recherche pour le développement in French

**GHG: Greenhouse Gas

Do you want to learn more about Lhyfe ? You can read our latest article on the topic here

Article written by Laurent Meillaud and translated by Logan King 

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About the author

Logan King

Logan King

After an unusual career (3 years in the French army followed by a 3-year degree in Applied Foreign Languages), it was my passion for environmental issues that finally caught up with me and led me to join Seiya Consulting and H2 Today in June 2022. First as an end-of-study internship, then as Marketing & Communication Manager and translator at Hydrogen Today.

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