Development of hydrogen infrastructure and optimisation of the electricity system in Auvergne-Rhône-Alpes Region
September 16th, 2025
A study conducted by NaTran-RTE-Storengy in collaboration with Auvergne-Rhône-Alpes Region confirms the benefits of developing shared hydrogen transport and storage infrastructure to optimise the electricity system and decarbonise industry in the case of production from flexibly operating electrolysers.
In July 2023, RTE and NaTran (then GRTgaz) conducted a study¹ to assess the challenges associated with developing hydrogen transport and storage infrastructure and ensuring its proper planning alongside electricity transport infrastructure. The analyses showed that the main benefit was to connect hydrogen basins to saline storage facilities so that electrolysers could offer their flexibility to the electricity system (a benefit of €1.5 billion/year for the entire energy system).
NaTran and RTE, in partnership with Storengy, worked on applying this study at the regional level in collaboration with the Auvergne-Rhône-Alpes Region, which is at the heart of industrial decarbonisation issues. Hydrogen transport and storage infrastructure is an essential technical lever for the flexibility offered by electrolysis to the electricity system. The study shows that pooling these infrastructures can strengthen the economic viability of flexibility (up to nearly 20% savings on the full cost of low-carbon hydrogen according to the assumptions, i.e. up to €1/kg).
Highly industrialised (Chemistry Valley, Greater Lyon, Alpine corridor, Ain Plain, Grenoble area, Rhône Valley, etc.) and therefore at the forefront of decarbonisation needs, the Auvergne-Rhône-Alpes region is a strategic hub in the national hydrogen roadmap:
- It has France's greatest potential for hydrogen storage in salt caverns in Etrez (Ain), operated by Storengy, whose brine caverns can be converted to hydrogen as early as 2030-2032.
- It is located on the route of the HY-FEN project, a hydrogen transport infrastructure on which NaTran is working with the aim of connecting hydrogen production, consumption and storage sites in France, while ensuring the transit of hydrogen between the Iberian Peninsula, France and Germany by 2030.
- As in all regions, RTE is studying opportunities to strengthen the electricity network, particularly to accommodate consumption by new industrial sites, for example in the Chemistry Valley (Vallée de la Chimie, Rhône) or at PIPA (Ain). This is the challenge addressed by the Ten-Year Network Development Plan.2
Hydrogen transport and storage infrastructure is a key technical lever for the flexibility that electrolysis offers the electricity system. The study conducted by NaTran, RTE and Storengy in collaboration with Région Auvergne-Rhône-Alpes confirms, in line with the national study conducted in 2023, that the pooling of hydrogen transport and storage infrastructure enhances the economic viability of the flexibility offered by electrolysis, which is necessary for the balance of the electricity system. The shared network structure proposed by the HY-FEN project and access to the Etrez underground storage facility would enable savings of up to 20% of the total cost of hydrogen produced, according to the assumptions, and promote the competitiveness of hydrogen solutions for decarbonising industry.
In line with national findings, shared underground storage in salt caverns is once again identified in this study as the most robust storage solution, particularly in terms of ensuring a high level of continuity of supply to connected industrial users and reducing the land impact of infrastructure.
In conclusion, the study highlights the need for coordinated planning at national and regional level for energy infrastructure, particularly for hydrogen transport and storage in salt caverns. Without the pooling of these infrastructures, the cost borne by each project could become prohibitive, slowing down investment and depriving the energy system of a valuable source of flexibility: according to the findings of this study, planning is therefore a prerequisite for optimally exploiting the flexibility potential of electrolysis.
1 Challenges in developing hydrogen storage and transport infrastructure associated with the development of electrolysis and levers for optimisation with the electricity system’, study by GRTgaz and RTE, July 2023 (here)
2 The main strategic guidelines of the SDDR (programme plan for the future of the electricity transmission network) have been subject to public debate led by the National Commission for Public Debate (CNDP) since 4 September 2025. This debate raises awareness and involves the general public in issues related to the development of the public electricity transmission network and the main guidelines proposed by RTE for 2040.
A review of energy planning already initiated by the industry
The findings of this study will inform multi-energy planning initiatives at both local and national level.
The work carried out by NaTran, RTE and Storengy in collaboration with the Auvergne-Rhône-Alpes Region will thus contribute to the planning exercises mentioned in the national decarbonised hydrogen strategy. At the territorial level, it will also inform the work of the recently launched Low-Carbon Industrial Zones (ZIBaC) initiative, such as the DeClyc (DECarboner LYon vallée de la Chimie) project, and contribute to the Auvergne-Rhône-Alpes Region's hydrogen strategy, which is currently under review.
NaTran and Teréga are currently conducting "Perspectives d’Avenir » (‘Future Prospects’)" consultations to enrich their infrastructure development plans with their stakeholders; the findings of the study conducted on the challenges of hydrogen infrastructure development in Auvergne-Rhône-Alpes will be used in this context, in particular to update the prospective hydrogen development plan.
3 ‘National Strategy for Carbon-Free Hydrogen 2025’, published by the Government in April 2025