how do gas storage sites work in France?

How to get out of the trap of dependence on Russian gas highlighted by thee conflict in Ukraine ? Europe is looking for ways to reduce this bias: the leaders of the 27 are considering setting up a common gas purchasing platform as a solution, as they have done for anti-Covid 19 vaccines. objective is also to have larger stocks: Brussels thus wishes to increase the reserves of gas stored in the basements, by fixing a minimum filling at the entrance of each winter. In France, this already exists: the gas is stored in depth in eleven sites spread across the country.

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In Lussagnet, not far from Mont-de-Marsan in the Landes, kilometers of pipes go in and out of the ground on the Téréga storage site. It is the second gas storage facility in France, after a subsidiary of Engie. With its two neighboring sites in the Bearnaise countryside, Téréga manages a quarter of France’s gas reserves, 500 meters below ground.

“The storage structure is a geological structure made of porous rock, it is finally sand, protected by about 500 meters of layers of clay, which ensures its tightness. This storage is several square kilometers of capacity“, explains Michel Boche, director of the group’s infrastructure projects.

Filling in summer

Like giant straws planted in the storage layer, several wellheads make it possible to fill or empty this geological reservoir. A highly regulated supply cycle: “The injection is done in summer, the withdrawal is done rather in winterspecifies Michel Boche. You inject gas when it’s cheap, and pull it out of the ground when demand is high. If we had no stock, we would be subject to the market price much more strongly, and we would undoubtedly have difficulty meeting the peak of extreme demand.

The stored gas does not belong to Téréga, but above all to the big suppliers of the market, for example Engie or the Italian ENI. It fills its reserves with gas purchased abroad, first in Norway, then in Russia.

For Thomas Pellerin-Carlin, energy specialist at the Jacques-Delors Institute, doing without Russian gas to fill stocks is possible, but under conditions: “This makes it more difficult, you have to play on several levers, the most discussed currently, and which is a necessary evil, it is the import of liquefied natural gas from abroad. This is something particularly economically expensive, and ecologically degrading, but it is necessary for the years to come. Then it is all the more easy to increase the stocks if we consume less. So all the gas that we continue to use these times- here to heat the café terraces, all this gas that we are wasting in March, we could very well store it.

Gas storage represents 20% of consumption in France, it would be essential in the event of an embargo on Russian gas, but not enough.