The project

First EU-supported large scale Green H2 Underground Storage Demonstrator

Hypster stands for Hydrogen Pilot Storage for large Ecosystem Replication

Officially launched in January 2021, the project aims to use salt cavern storage to connect hydrogen injection by electrolysis to industrial and mobility uses. It will also test the technical and economic reproductibility of the process to other sites throughout Europe.

In partnership with ESK GMBH, ARMINES-Ecole Polytechnique, Ineris, AXELERA, Element Energy, Storengy, INOVYN, Brouard Consulting and Equinor, this project is part of a dynamic region with growing green hydrogen uses.

Etrez : A site located ideally at the crossroads of production, storage and consumption.

Located north-west of Bourg-en-Bresse, on the north-south European corridor, the Etrez storage site is the largest French natural gas storage site in salt caverns in terms of capacity.

Hypster is at the heart of the Auvergne-Rhône-Alpes Region and will participate to the French regional hydrogen stragegy with other significant projects (Zero Emission Valley, the construction of hydrogen production units and filling stations in the region of Bourgogne-Franche-Comté, the Chemical Valley) by making possible the development of a local hydrogen hub to reduce atmospheric and noise pollution thanks to a transition towards hydrogen mobility and on the other hand, to decarbonise other local uses.

Key figures




1st demonstrator of Hydrogen green storage


Total budget:


5-million-euro granted by the Fuel Cells and Hydrogen Joint Undertaking FCH JU)


Production of 400 kg of hydrogen per day

(the equivalent of the consumption of 16 hydrogen buses).




3 tons

of green hydrogen to be stored  during the first stage

The project timeline


Definition of the regulatory framework for the project & signature of the consortium agreement by all partners


Start of the engineering studies.


Construction of the electrolysis unit for on-site green hydrogen production.


Experimentation of hydrogen storage in a salt cavern and hydrogen production.

*One bus tank containing 25 kg of hydrogen

Downstream applications for the green hydrogen produced on-site

The hydrogen produced on site will be distributed by trucks in the region within a radius of 150km, mobilising public and private key players in the region for two kind of use :
Decarbonizing industrial uses of hydrogen consumers by switching from a supply of grey to green hydrogen.
Power hydrogen refueling stations for green mobility (lorries, buses, vans, garbage trucks, etc. ).

The objective of the project is also to massify uses in order to optimize the price of hydrogen for final consumers. In addition, Etrez is well-positioned for European gas carriers to contribute to « The European hydrogen Backbone » a hydrogen network. It will ensure the flexibility of the network and the security of supply in a cross-border context with potential hydrogen exports to Germany.

Thanks to hydrogen underground storage facilities acting at intermediary between intermittent production and variable hydrogen demand, many other hydrogen projects will be able to be developed at a European scale.

A unique technique

The storage of hydrogen in salt cavern, located between 500 and 1.500 meters below our feet, is the most advanced solution for storing energy over several months or years.

Generic scheme for the storage of hydrogen in salt cavern

The purpose of this project is to demonstrate technical feasibility of underground hydrogen storage in terms of safety and environmental impact. It will make it possible to determine the cost of hydrogen storage, the place of underground storage in the hydrogen value chain and the quality level of hydrogen after extraction from the cavern.

As an investor, designer, builder and operator of the facilities, Storengy aims to replicate hydrogen underground storage on other natural gas storage sites in order to contribute to the development of hydrogen ecosystem.

Thanks to the expertise of the different partners involved, HyPSTER will contribute to the development of a strong hydrogen ecosystem.

A closer look at hydrogen:

Hydrogen from renewable production has a prime position in energy transition.
It can be used for a variety of purposes:
– in the industry (chemical, electronic, glass, metal…), hydrogen can be used to produce different materials, but also for energy purposes (steam, for instance), and to lower the carbon intensity of the production chain;
– in transports and mobility, it replaces traditional fuels with the advantage of not generating any emissions while offering significant autonomy and very short refuelling time.

Green hydrogen, renewable energy sources contribute to the decarbonisation of industrial and mobility sectors.