From gas to hydrogen, storage player Storengy is preparing for the future

“We cannot follow a logic where we wait for the hydrogen market to be ripe to decide that we want storage because otherwise, we will have a delay in the establishment of the market,” indicated during a press conference on Thursday the new general director of Storengy, Charlotte Roule.

“The objective for Storengy is to convert all of our salt cavities to hydrogen,” she explained.

The operator has four sites in salt cavities where the gas is stored in artificial underground caverns with watertightness guaranteed by the rock salt of the rock: Hauterives and Tersanne (Drôme), Manosque (Alpes-de-Haute-Provence) and Etrez (Ain), i.e. a capacity of 12 terawatt hours out of the 100 TWh operated by Storengy. The Terega company operates the rest of the French gas storage capacities, amounting to 34 TWh.

On the eve of winter, these storages are almost 100% filled with gas to supply the boilers and their capacities have already been largely pre-sold until April 2026, to around forty gas suppliers.

But in the future, Storengy sees hydrogen storage as a way to support project leaders.

The storage would be available to serve industrial customers, even when the electrolyzers, which consume a lot of electricity, have to stop due to tensions on the electricity network.

Studies by operators of the electricity transmission networks, RTE and, gas, GRTgaz cited by Storengy estimate the hydrogen storage needs at around 10 to 25 TWh in 2050, and Storengy already estimates that the conversion of all its saline capacities will not be enough.

The operator is therefore investing first in the expansion of its Etrez site to increase its current storage capacity in salt caverns by 10%.

This expansion, authorized at the end of July by the Energy Regulatory Commission (CRE), will add an additional 1,6 TWh to its salt cavern storage capacities.

100% green gases in 2050?

Still in Etrez, in the town of Bresse-Vallons, Storengy has just inaugurated its HyPSTER project where a test phase with around a hundred hydrogen pressure variation cycles must start to confirm the capacity to store hydrogen in safely, because this gas is highly flammable and very reactive.

The salt cavity tested is backed by an electrolyser with a power of 1 MW powered by solar and hydraulic electricity and this first underground hydrogen storage project in the European Union mobilizes 15,5 million euros of investment. investments.

Storengy will start small, with test production equivalent to the consumption of 16 hydrogen buses, but it foresees "in the longer term" that there will be four cavities at Etrez at a depth of 1.300 meters dedicated to hydrogen, with a capacity storage of 6.700 tonnes each.

The operator has obtained an exclusive research permit in the Nancy sector (Meurthe-et-Moselle) to develop hydrogen storage in a salt cavity, and submitted two other permit applications in Alsace, near Sélestat and Mulhouse.

For the moment, Storengy only stores gas, including a very small proportion of biogas (from biowaste or agricultural residue). It is “of the order of 5%”, according to Ms. Roule, although this source of renewable energy meets the needs for security of supply, energy independence and decarbonization of energy.

By comparison, “Denmark today accommodates 30% biomethane in its storage,” recalls Storengy.

“By 2050, there will only be renewable gases in our storage”, whether hydrogen or biomethane, argued Ms. Roule.

Unlike hydrogen, the storage of biomethane requires little investment: “We are more in the process of adaptation,” according to Ms. Roule. Biomethane is intended to be accommodated in aquifers, underground layers of rock which originally housed water and which are used for seasonal storage of gas underground. From the outside, they most often take the shape of a dome.