Engineering a Hydrogen Valley

Inside the design of LuxHyVal’s production and storage system

When most people think about the energy transition, they picture solar panels on rooftops or wind turbines on hilltops. Green hydrogen asks for something more: it asks us to build an entirely new industrial chain, from scratch, in places where none existed before. That is exactly what the LuxHyVal consortium set out to do in the south of Luxembourg. The engineering challenges involved proved as fascinating as they were consequential.

This article takes a look behind the scenes at how LuxHyVal approached the design of its green hydrogen production and storage system: what technologies were at the core, what decisions proved harder than expected and why getting this right matters well beyond Luxembourg’s borders.

Splitting Water at Scale: the PEM Electrolyser at the Heart of the System

Green hydrogen is, at its most fundamental level, the product of splitting water using electricity. When that electricity comes from renewable sources, the result is a fuel with no direct carbon emissions, a crucial property for sectors that cannot simply be electrified, such as heavy transport and industrial processes.

The technology chosen for LuxHyVal’s production facility is a Proton Exchange Membrane (PEM) electrolyser. PEM electrolysis emerged as a strong candidate for several reasons: it responds dynamically to fluctuations in power input, making it well-suited to couple with variable renewable electricity sources such as solar and wind; it produces high-purity hydrogen; it has a compact footprint relative to its output capacity; and — unlike alkaline electrolysis — it requires no caustic chemicals such as potassium hydroxide (KOH) on site, an important advantage from a safety and operational perspective.

The plant is designed for a production capacity of 5 MW, a scale that is meaningful in the context of a first-of-its-kind project in Luxembourg, while remaining technically and operationally manageable as a learning platform. The facility will be located in an industrial zone in the southern part of Luxembourg, a region with a deep industrial heritage that provides both the infrastructure and the industrial culture needed to host this kind of innovation.

The coupling of the electrolyser with renewable electricity was not a trivial design challenge. Both solar and wind generation are inherently variable: solar panels ramp up at dawn and dip on cloudy days, while wind output fluctuates with meteorological conditions. The PEM unit had to accommodate this variability while maintaining safe operation and maximising hydrogen output. This interface between the power supply and the electrochemical process was one of the central engineering challenges the project team worked through during the design phase.

Storing What You Produce: Safety, Logistics, and the Art of Minimising Inventory

Producing green hydrogen is only half of the equation. Storing it safely and efficiently while also making it available when and where it is needed is the other half, and in some ways the more demanding one.

LuxHyVal’s storage solution is based on compressed gas technology: hydrogen is stored in high-pressure vessels after being compressed from the electrolyser output. This is a mature and well-understood approach, but its application within an active industrial zone raised specific questions that the design team had to address carefully.

One of the most thought-provoking aspects of the storage design was the question of logistics integration. The production site sits within an existing industrial area with established traffic flows, infrastructure constraints, and neighbouring activities. Introducing hydrogen tube trailers, the vehicles used to transport compressed hydrogen to end-users as well as hydrogen buses, meant thinking carefully about how this new traffic integrated with what was already there. Access routes, turning radii, loading bay positions, and traffic scheduling were all part of the conversation.

Closely related to this was a design principle that guided much of the team’s thinking: minimise the quantity of hydrogen present on site at any given time. This may sound counterintuitive: why build a storage system only to keep it as empty as possible? But it reflects a fundamental aspect of hydrogen safety management. The smaller the inventory on site, the smaller the potential consequence of any unforeseen event. Rather than compensating for this through large buffer stocks, the project team developed demand planning tools and scheduling logic that synchronise production with offtake as closely as possible. The storage system was designed to play the role of a buffer, not a warehouse.

Safety and risk modelling were integral to this approach. Working within applicable European regulations and industry standards, the consortium developed a comprehensive safety case that accounts for the specific characteristics of the site: its geometry, the surrounding activities, emergency access, and the particular behaviour of hydrogen as a gas, which differs significantly from conventional hydrocarbon fuels.

From Atoms to Applications: Who Uses This Hydrogen, and How?

A production and storage system only makes sense in the context of the demand it serves. LuxHyVal’s hydrogen production was designed for two primary categories of use: mobility, in particular buses, and industrial feedstock applications. Both of these use cases share a key property: they are hard or uneconomical to decarbonise through direct electrification, which is precisely where hydrogen plays a distinctive role.

For mobility applications, hydrogen is dispensed at an on-site refuelling station, where it is transferred into the onboard tanks of fuel cell buses at high pressure. The logistics connecting production to this dispensing point are tightly linked to the storage design described above: production scheduling, storage buffer sizing, and refuelling demand were all modelled together to arrive at a coherent system.

For industrial feedstock use, hydrogen replaces fossil-based hydrogen inputs in manufacturing processes.

Underpinning both use cases is the question of green certification. For hydrogen to qualify under EU regulations as a renewable fuel, it must be demonstrably produced from renewable electricity according to specific methodological rules, the so-called Renewable Fuels of Non-Biological Origin (RFNBO) framework established under the Renewable Energy Directive. LuxHyVal’s hydrogen production system was designed from the outset to comply fully with this framework, ensuring that the hydrogen delivered to end-users can be certified as genuinely green. This is not a bureaucratic formality: certification is what gives green hydrogen its economic and environmental value proposition, and it was treated as a non-negotiable design requirement from day one.

“Certification turns molecules into value. Without it, green hydrogen is just hydrogen — and that changes the entire business case.”

Optimising the System: Where Engineering Met Economics

None of the design choices described above existed in isolation. The electrolyser capacity, the storage volume, the demand scheduling, the safety layout, and the certification requirements all interact. Changing one parameter ripples through the others. This was the domain of techno-economic optimisation, and it was one of the areas where Paul Wurth together with ENOVOS invested the most significant analytical effort.

The questions were concrete: What is the right size for the electrolyser given the available renewable electricity profile from both solar and wind sources? How much storage buffer is needed to avoid production curtailment without accumulating excess inventory? What is the break-even cost of hydrogen production at this scale, and how does it evolve as the technology matures and electricity costs change? How do different demand scenarios affect the overall economics?

Working through these questions rigorously was what allowed the project to move from concept to a technically and economically coherent design.

In this sense, LuxHyVal did not just design a hydrogen facility. It built knowledge which may prove to be its most durable contribution to the evolution of other hydrogen valleys.

Looking Ahead

With the design and optimisation phases now complete, LuxHyVal moves forward with the confidence that comes from rigorous engineering work. What the design process made clear is that building a green hydrogen valley is a genuinely multidisciplinary endeavour: it sits at the intersection of electrochemistry, mechanical engineering, logistics, safety science, market economics, and regulatory affairs. It requires all of these disciplines to work in concert.

Enovos, which will own and operate the production plant with the support of LuxEnergie, brings operational experience in energy infrastructure that is essential for translating engineering design into a functioning facility. Paul Wurth, as engineering partner, contributed its deep expertise in complex industrial energy systems and project execution. Together with the wider LuxHyVal consortium, these partners worked to ensure that when this plant is commissioned, it will serve as a genuine reference case, not just for Luxembourg, but for hydrogen valleys across Europe.

We invite you to follow the LuxHyVal project as it progresses. Subscribe to our newsletter or visit luxhyval.eu to stay informed of consortium news and publications.

Author

Davide Galloni — Sales Manager, Paul Wurth S.A. (SMS group), Luxembourg. Davide works within the LuxHyVal consortium on technical aspects of the project’s hydrogen production and distribution system.

Funding disclaimer: The LuxHyVal project has received funding from the European Union’s Horizon Europe research and innovation programme under Grant Agreement No. 101111984 and is co-funded by the Clean Hydrogen Joint Undertaking. Views and opinions expressed are those of the author only and do not necessarily reflect those of the European Union or the Clean Hydrogen Joint Undertaking.