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Lhyfe says objectives of Sealhyfe offshore hydrogen production pilot met; on to HOPE

Lhyfe, one of the world’s pioneers in the production of green and renewable hydrogen, announced that the operating results of its offshore hydrogen production pilot platform, Sealhyfe, which returned to dock in November 2023, confirm that the initial objectives have been met and enable another step forward for the company.


Right: Sealhyfe, an offshore hydrogen production pilot (Lhyfe) equipped with a Plug electrolyser, on the WAVEGEM platform (GEPS Techno), Left: the FLOATGEN floating wind turbine (BW Ideol) on the SEM-REV sea trials site (Centrale Nantes/OPEN-C) ©Lhyfe

The Sealhyfe project, equipped with a 1 MW electrolyzer supplied by Plug, aimed to demonstrate that producing hydrogen offshore from renewable energy sources is already a reality. More specifically, the experiment aimed to:

  • Demonstrate Lhyfe’s ability to operate an industrial-scale production unit (1 MW) in an isolated environment;

  • Prove the reliability of the electrolysis technology in harsh environmental conditions that are representative of the operating conditions of its future large-scale offshore sites; and

  • Provide a database of operating data that can be used to optimise and make production processes more reliable, and to test the technologies employed with a view to scaling them up to sites with ten times and then 100 times greater capacity.

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 review of test results and analysis of equipment after 14 months of trials found:

  • System responsiveness and versatility: As offshore hydrogen production is particularly relevant for providing services to the electricity grid, Lhyfe repeatedly tested the system’s versatility and responsiveness in a wide range of 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.

  • Robustness: Throughout the trial, the production system equipment designed by Lhyfe was tested in extreme conditions for platform movement management, environmental stress, etc. In particular, Sealhyfe was confronted with five significant storms, including Ciaran, which swept along the Atlantic coast in October 2023, with waves over 10 metres high and winds of more than 150 km/h. 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.

  • Equipment and system optimization: Throughout the experiment, on-board and remotely-controlled measuring instruments were used to identify ways of optimising the efficiency and reliability of Lhyfe’s production units – including safety systems, electrical architecture, automation, fluid and stock management, etc. – for its other projects.

  • Remote control: The quayside benchmark testing phase helped to de-risk the project. The vast majority of impacts specific to offshore hydrogen production were identified and reduced. The site was then operated exclusively remotely from Lhyfe’s control centre, 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.

  • Regulatory developments: 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.

Overall, the Sealhyfe project enabled Lhyfe to develop its expertise in handling the constraints associated with offshore industrial deployment, thanks in particular to its experience integrating an isolated, offshore plant on a floating barge at sea.

The results of this experiment are already being incorporated into the HOPE project, which represents the second stage in Lhyfe’s offshore ambitions. This project, which Lhyfe presented with a consortium of nine partners, was selected by the European Commission for a €20-million grant as part of the Clean Hydrogen Partnership, along with an additional €13-million grant from the Belgian government.

With HOPE, Lhyfe and its partners are changing scale and aiming to commercialise green hydrogen produced offshore. From 2026, this unprecedentedly large-scale project (10 MW) will be able to produce up to 4 tonnes per day of green hydrogen at sea, which will be exported ashore by pipeline, and then compressed and delivered to customers.

The Sealhyfe project will also ensure that the production processes at Lhyfe’s land-based sites are reliable and optimized from the outset, so that they can be ramped up quickly and progressively. Lhyfe’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.



I wondered where the water was to come from, as hydrogen production direct from seawater is still very early stage.

The answer is that they are to desalinate it onboard (Fr):

' Système de traitement de l’eau de mer. Ce système peu énergivore, compact, économique et capable d’utiliser la chaleur émise par l’électrolyseur, sera pour la première fois utilisé pour produire de l’hydrogène vert à partir d’eau de mer purifiée par évaporation.'

So some of the energy for desalination is to come from otherwise waste heat from the electrolyser.

The initial installation is to be close inshore, just off the coast of Belgium, where there is good hydrogen infrastructure to utilise the product.

I am particularly keen on the project backed by Ikea to release the oxygen from offshore windfarms into the Baltic sea instead of the air, so countering the oxygen depletion there.

A great ecological freebie.

They are looking at the same idea in Canada.


I then wondered how Japan is doing in developing floating wind turbines, as apart from imports and with deep water close inshore in most places, it is the only really large scale way for them to get renewables, with limited land available for solar.

The potential is indeed enormous:

' Japan has enormous offshore wind resources. Its total technical potential for offshore wind generation is over 9,000 TWh/year, more than nine times its projected electricity demand in 2050.'


Reading up there, shallower water not needing floating turbines is also a much greater resource than I had imagined:

' The Global Wind Energy Council (GWEC) estimates there is potential for around 128 GW capacity for fixed bottom projects in shallow waters, and 424 GW for floating offshore wind in deeper waters. '

Current installed capacity is miniscule:

' In 2022, there was 91 MW of offshore wind in Japan, 5 MW of which was floating offshore wind. These small scale demonstration projects are expected to deliver valuable technical lessons for the offshore wind industry in Japan. This capacity increased in February 2023 when the country’s first large-scale offshore wind project (140MW) began commercial operation at Noshiro Port in Akita Prefecture.'

And their first floating wind farm trial is running into hassles and delays:


' Japan’s Goto Floating Wind Farm Consortium has postponed the commissioning of the Goto City Offshore Wind Power Generation Project by two years following the discovery of defects in the floating structures to be used for the project.'

So massive potential, and slow and hesitant implementation.

Albert E Short

I liked it up to "green hydrogen [...] will be exported ashore by pipeline". A big challenge for less-than-close to shore wind is bringing the electricity ashore because wiring is expensive. I have to think a wire is cheaper and more durable than a pipeline for volatile gas. What happened to generating ammonia or hydrides and bringing them back on shore via drone boats?


Make cheap carbon neutral egasoline with this hydrogen and completely stop investing in costly subsidized batteries. The worldwide economy will rebound as soon as car drivers and truckers start filling up with clean cheap fuels and goverments stop subsidies to catastrophic electrification.


Hi Alfred.

AFAIK the answer to how to bring power ashore is pretty much: 'It depends'

Here are a couple of references:


Note in the abstract:

' Hydrogen pipelines offer the advantage of transporting larger energy volumes, but existing projects are dwarfed by the vast networks of HVDC transmission lines. '

' Considering these technologies as standalone competitors belies their complementary nature. In the emerging energy landscape, they will be integral components of a complex system. Decisions on which technology to prioritize depend on factors such as existing infrastructure, adaptability, risk assessment, and social acceptance. Furthermore, while both HVDC lines and hydrogen pipelines are
expected to proliferate, other factors such as market maturity of the relevant energy vector, government policies, and regulatory frameworks around grid development and utilization are also expected to play a crucial role.'

And here:


' Four different scenarios were explored. The first two scenarios evaluated the power transmission of 2 GW between two shores separated by either shallow or deep waters. Whilst the remaining two scenarios analysed the power transmission of 600 MW between an offshore platform, close to an offshore wind farm, and its hinterland, in shallow and deep waters. For bulk power transmission of electricity, the use of a high voltage direct current through submarine cables was studied. In the case of hydrogen, two transport alternatives were evaluated: hydrogen transported through pipelines and by ships in liquefied and compressed states. The findings of this study indicate that for a 2 GW power transmission and distances slightly over 1000 km in deep waters, the hydrogen transported through pipelines is cheaper than electricity, even when the electricity prices are low. Overall, among the hydrogen transport alternatives, the best solution is to transport liquefied hydrogen by ship.'

Turning the power into ammonia is pretty much only considered for longer distances, where you have to use tankers, for instance from the Arabian Gulf to Europe, as conversion to ammonia and back again, with its own issues of being very nasty to handle, takes a lot of energy and ammonia is not (?) usually piped.

The basics of transmission technology is that one hydrogen pipeline carries as much energy as several HVDC cables.

For the North Sea, existing NG pipelines ready for conversion reduces costs, so the rough guide that they are usually better for over 1,000km does not apply.

For deep sea work, ie floating offshore wind, the main line of thought is to send in hydrogen tankers to take off the product, which obviously would not be possible with electricity,

My own take is that piping hydrogen as opposed to electricity enables both far more efficient use, as it can be converted right where it is needed to electricity and heat, at stonking efficiency, and helps in storing energy, as hydrogen and its derivatives are far more storable than electricity,

And to back that up, and without wishing to show off, I must point out that I have a Chemistry 'O' Level, (1966), so expertise is not lacking, and was obtained prior to many of my critics,! :-0


And here is how the technology of producing hydrogen direct from seawater without bothering to desalinate it is going:


' The research group developed a multi-elemental alloy electrode composed of nine non-noble metal elements and conducted an accelerated degradation test, consisting of turning the power supply on and off, which mainly caused degradation during the operation of the water electrolysis system.

The results suggest sustained anode performances for over a decade when powered by solar energy.'

So the answer is: 'Pretty good'

It should be noted though that desalination is not a major cost anyway of producing hydrogen at sea:

' Desalination is an expensive water source for most industries – except green hydrogen. This is because it costs 50 KWh of energy to make 1 KWh of hydrogen, but it only takes 3 KWh to make 1000 kg of desalinated water.'


I dunno if that even takes account of energy input reduction due to using the waste heat from electrolysis for desalination, but in any case there is not really a problem.


Some more info here:


' “The performance achieved was as high as on land, confirming the reliability of the installation,” the developer said in a press release. It also confirmed to Hydrogen Insight that Plug’s electrolyser had a working range of 10-100%, meaning that it could produce H2 when the electricity input was as low as 10% of its nameplate capacity (ie, 100kW).'


' Lhyfe also confirmed to Hydrogen Insight that the project only produced 15 tonnes of H2, or around a quarter of the maximum output possible, assuming full utilisation for all of the days it was producing hydrogen at sea. However, it added that the focus of the project was technical feasibility in harsh marine environments rather than maximising production.'

But it would seem that like a lot of renewable technology, nameplate capacity and actual output will be very different.

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