Welcome and Introduction
Good morning everyone, and welcome to today's H2conf webinar. Thank you for joining us for this session with Vallourec on sizing hydrogen systems — solving the storage challenge for industrial projects and Power-to-X.
We are very pleased to welcome Ms. Katrine Hagege. She is the Business Development Manager for the European and African region for Delphy by Vallourec. Today's session will focus on one of the most important questions for hydrogen project development: how storage can support more reliable, flexible and practical industrial hydrogen systems.
Before we begin, a quick note — this webinar will include a presentation followed by a Q&A session, so please feel free to add your questions in the Q&A section during the presentation and we will address them at the end. The replay of this session will be available in a few days on our website.
Katrine, thank you for joining us today — we are happy to have you here. The floor is yours.
Thanks a lot. Good morning everyone — thanks for the introduction and for inviting me to participate in this hydrogen conference track.
Over the next 20 minutes I will introduce Vallourec and Delphy, our underground hydrogen storage solution, and explain how large-scale hydrogen storage can really support industrial and Power-to-X projects.
We believe, within the Vallourec and Delphy team, that storage is a key enabler of the hydrogen economy and a key enabler to scale up Power-to-X projects. It addresses some of the major challenges that project developers are facing, especially when they are looking to include storage in their projects — meaning safety, footprint, operational flexibility, and ultimately project economics.
We will try to keep the presentation concise. Please don't hesitate to write your questions or comments in the chat. Igor, my colleague, will try to answer them throughout the webinar — otherwise, at the end we will have enough time to address those questions. Thanks again for joining, and I hope you will enjoy the coming 30 minutes.
About Vallourec
First, a few words about Vallourec. Vallourec is a French company with approximately €4 billion in revenue and is recognised as a global leader in premium seamless pipes. We produce seamless pipes mainly today for the oil and gas industry, but we are now leveraging decades of expertise in steel making, threading, heat treatment, and high-performance connections to support the energy transition.
We have a team working on other types of applications — geothermal, CCS, hydrogen transport, and hydrogen storage. Igor and I are part of the Delphy team, which is the name of our hydrogen storage solution. We operate as a kind of startup within a large group, reporting directly to the CEO in order to accelerate innovation, and we are specifically focused on hydrogen storage.
Why Large-Scale Hydrogen Storage?
We see — and that is great news for the sector — that green hydrogen projects continue to scale up, and the need for storage is becoming more and more crucial. For our customers, storage is not seen simply as a commodity asset; it is really seen as a strategic tool to improve production efficiency and optimise the project business case.
Why is it so important?
It is a way to manage electricity coming from renewables — solar and wind — producing and storing hydrogen when the electricity price is low and using the hydrogen when the electricity price rises.Many projects are producing not just hydrogen but derivatives. Downstream applications such as e-fuels, green ammonia, or green steel need to operate under stable conditions. Avoiding stoppages within the process helps increase efficiency and ensures the full industrial setup is properly managed.We see across different clients — and this comes up in our discussions — that storage can help manage intermittency from renewables, but also act as a buffer to ensure steady consumption, reliable supply, and improved overall operational stability.
The Value of Storage Model
Something we have worked on over the last few months is the value of storage — a model we have developed and are presenting to many of our clients. Behind a storage asset there is often a CAPEX, so the idea is not to ask "how much does the storage cost?" but rather "what value can the storage bring, and what is the return on investment?"
We work on this model and analyse it with our clients. The key value levers are:
Renewables intermittency management — the ability to cope with variable renewable generation.Electricity price arbitrage — buying and storing when prices are low.Full value chain optimisation — working with our partner Nexeom, we have shown that including storage in a green ammonia production loop can help reduce the LCOA by 15%.Avoiding equipment oversizing — some projects oversize electrolysers or compressors to manage potential equipment failures. Having a storage buffer can avoid this extra CAPEX.Avoiding production stoppages — maintaining an ongoing supply of hydrogen avoids losses that can be very costly for applications like green ammonia, eSAF, and especially green steel.In short, storage brings value and is becoming a key component of bankable hydrogen projects. Depending on the application, the location, and the size of the project, clients will adapt the storage capacity they need in their industrial setup.
The Hydrogen Storage Landscape
Despite its value, hydrogen storage remains challenging. There are different types of hydrogen storage available today:
Salt caverns — a good way to store very large capacities (thousands of tons of H₂), but they require the right geological conditions, grid connections, and can take seven to nine years to set up.Above-ground cylinders — an interesting option, but once you need to store a few tons of hydrogen, footprint and safety considerations start to become challenging.This is exactly where Delphy has been developed, with storage capacity between 1 and 100 tons:
1–3 tons — typically mobility applications.5–15/20 tons — applications such as eSAF, particularly in a European context.Above 100 tons — large projects such as green steel and green ammonia, including projects we have in discussion in the Middle East.
What Is Delphy?
Delphy is Vallourec's turnkey underground hydrogen storage solution — and "turnkey" is a keyword to keep in mind, because it is not just the pressure vessels; it is the full setup.
The solution assembles our seamless pipes, connected with fittings that are certified for hydrogen service. You build a cavity — and we work with civil works partners on this. Depending on the quantity of hydrogen to be stored, the target pressure, and the soil conditions at the project site, the size of the cavity is adapted. Those civil works partners have the capability to build cavities down to 100 metres depth, and the diameter of the cavity is also adapted to the hydrogen quantity and pressure required.
Inside those pressure vessels, hydrogen is stored in compressed form, typically between 200 and 350 bar for industrial applications. Some projects are looking at approximately 500 bar, but this is mainly for refuelling stations.
This configuration enables storage of 1 to 100 tons of hydrogen with a very limited footprint — something I will detail further in a moment.
The Demonstrator
In the middle of the slide, you can see a picture of our demonstrator, located in the north of France. You are all very welcome to come and visit it.
We built and commissioned this demonstrator in 2023 — so this is not just a concept on a slide; it is a solution that has been in operation since 2023. It was built to validate all key aspects of the technology, including:
Filling and emptying cyclesPressure cycling and performanceSafety systems — ultrasonic sensors to detect leaks or the start of a fireVentilation systemsWater managementMonitoringAll of this work was supported by Vallourec's R&D capabilities, covering material testing, fatigue assessment, simulation, and operations.
Qualifications Achieved
Equipment qualification from Bureau VeritasMore recently, a full-system qualification from DNV — helping us move into the commercialisation phase
Key Advantages of Delphy
Safety
Safety is at the core of the design. We have conducted several quantitative risk assessments comparing Delphy to above-ground solutions. Key results:
Safety exclusion zone reduced by a factor of 2, because the storage is underground with a limited footprint and less instrumentation.Footprint reduced by up to 30 times versus above-ground solutions.This is a key driver for projects in Europe, where you often have cluttered environments — industrial sites, port areas, or refuelling stations with busy surroundings and residential areas nearby. An underground, invisible storage asset is a very compelling proposition. We have also heard this argument in the Middle East and Northern Europe: being underground means the contents of the cavity are not visible, which also provides resilience against risks such as drone attacks.
Flexibility and Modularity
The cavity size can be adapted to the quantity of hydrogen to be stored.The storage can be scaled up as needed.Pressure groups can be configured independently.On the right-hand side of the slide, you can see a picture of the top of the demonstrator cavity. We have seven strings going down to 20 metres and three pressure groups, used to test pressure cycling and to demonstrate how multiple pressure groups can be used to optimise an industrial setup. This is something we discuss with developers depending on the storage purpose and project size.
Safe by Design
Safety is of course critical when handling hydrogen, and it was a very strong focus when we developed the solution.
Pressure Vessel Design
Hydrogen-compatible steel, validated by a comprehensive test programmeCE/PED certifiedHydrogen cycling tested within the pipesLeak-tight connections using our BAM21 connections, certified for hydrogen servicePassive Safety Features
Two key passive safety features are built into the design:
1. Top cavity natural ventilation — if there is a leak from the tubes or connections inside the cavity, the hydrogen molecules bubble up and disperse into the top cavity, which is naturally ventilated. We have run ventilation simulations to demonstrate this.
2. Water inertisation — all strings are supported by a support plate, and everything below the support plate is submerged in water. This eliminates the risk of an explosive atmosphere below the plate.
Quantitative Risk Assessment Summary
We ran a QRA comparing 10 tons of Delphy versus 10 tons of above-ground storage:
Leak frequency from instrumentation reduced by a factor of 3, due to the limited footprint and less instrumentation.Size of the flammable cloud reduced by a factor of 6.We also ran the equivalent analysis for a 20-ton configuration. We are happy to discuss these in more detail under NDA.
Turnkey System and Lifetime Services
Delphy is much more than storage vessels alone. The system includes:
Instrumentation and automationA dedicated control room shelter (depending on project configuration)Everything delivered, installed, tested, and commissionedBeyond commissioning, we also offer lifetime services:
MonitoringInspectionMaintenanceSpare parts managementLong-term operational support when neededThe objective is to maximise reliability while optimising operating costs — a turnkey storage solution supported by an LTSA with our team.
Case Study
We have been running a series of case studies for clients using our value of storage model. This particular case study is for a project currently in pre-FEED phase:
300 MW electrolyser capacity44,000 tons of H₂ production per yearDelphy storage capacity: 10 tonsBy running the model — considering electricity price arbitrage, process buffering, improved operational flexibility, and the avoidance of production stoppages — we arrived at a payback period of 2 years.
Conclusion
Hydrogen storage is a key enabler for the deployment of large-scale hydrogen projects. It is a great way to optimise the full industrial setup, reduce costs through its buffering role, and ultimately improve project economics.
Delphy offers a safe, compact, scalable, ready-to-deploy solution that makes large-scale hydrogen possible.
We are very happy to assist you — to discuss your project, run a preliminary assessment of your storage needs, explain the technology in more detail, and introduce you to the demonstrator.
We have group visits organised. The next one is on 29 October, just after Hydrogen Week in Brussels, in Aulnoye-Aymeries in the north of France. You will see the demonstrator as well as Vallourec's R&D facilities. We will send a link through H2conf so you can find out more about this visit.
We also provide engineering services for pre-FEED and FEED stages.
Thanks again for listening. I will now turn to the questions — and there are a lot of them!
Audience Questions
Civil works scope
Q: Are civil works included in the proposal?
Civil works are not directly within Delphy's scope in the sense that they are typically part of the full EPC setup for the site, with storage being one piece of that overall construction work. However, we are in contact with many civil works partners around the world, and we introduce clients to those partners, because there are often many questions about the capability to build the cavity.
There is then a three-party discussion: depending on the soil conditions at your project location, there is an impact on the cavity design. We work with civil works partners to find the optimum cavity design and the right balance between civil works cost and our cost. With Delphy, the deeper you go, the fewer strings you need, less instrumentation is required, and therefore a more efficient CAPEX is achieved.
Compression scope
Q: Is compression included?
Compression is not in our scope, but we have signed an MOU with Baker — non-exclusive — to address this question, which comes up most of the time. Our sweet spot for storage pressure is around 325 bar, and within the 200–325 bar range this has a very positive impact on storage cost, clearly compensating for the extra compression cost. It is something we can work through in detail for specific projects.
Typical payback period and applications
Q: What is the typical payback period, and for which applications?
For the case study shown, we used 325 bar. We have run cases for eSAF, green steel, and green ammonia. We also see projects coming in from data centres, where having hydrogen storage on-site can be very interesting. We are happy to work on your specific case — looking at footprint constraints, safety requirements, and optimum storage size for your application.
Request for quotation for 10 tons
Q: There is a request for a quotation for 10 tons.
10 tons is a very typical storage size we see. We can discuss it further depending on the pressure requirement and the location of your storage. As a general point, from 10 tons upward, Delphy tends to be more cost-efficient than an above-ground solution — comparing apples to apples.
Hydrogen piping and transport in France
Q: Question on hydrogen piping in France.
That is actually managed by our hydrogen piping team, which is focused on delivering pipe for hydrogen transport applications. It is separate from the Delphy storage team, but we can put you in contact with that team directly.
An additional note: our pipes have also been used for salt cavern applications — for projects from Gaz Uni and Storengy — on the piping side.
Thanks again for your time and for joining the conference, and for all your questions. If you have any additional questions, you will receive the presentation — don't hesitate to reach out. We would be more than happy to discuss your project further.
And remember — on 29 October we have a visit in Aulnoye-Aymeries. Please do join us. It will be a pleasure to welcome you there. Thank you, everyone.
