It’s the biggest methanizer of France. In Mourenx (Pyrenees-Atlantiques)the new website of TotalEnergiesBioBéarn, produced its first cubic meters of biogas in January and should eventually supply 30,000 households annually.

In this town in the Lacq basin, which for sixty years was at the foot of the Pyreneesthe largest deposit of gaz natural gas operated in France, the industrial site is now focusing on renewable energies.

220,000 tons of organic waste, or “60 trucks per day”

At full capacity, BioBéarn will produce 160 GWh of so-called “green” gas annually, or the equivalent of the annual consumption of 32,000 households. This new biogas plant, the group’s eighth in France, required an investment of 50 million euros. In 2023, the start-up year, “we will make half the capacity of the site before ramping it up”, explains Olivier Guerrini, manager of the biogas sector for the French energy giant.

The methanizer will eventually receive 220,000 tonnes of organic waste, or “60 trucks per day”, underlines Omar Boufares, director of the Bearn site, and will in return generate 200,000 tonnes of fertilizer product for agriculture.

On its three-hectare tarmacked unit, BioBéarn recovers the vast majority of waste from agriculture, of animal or plant origin, but also sludge from treatment plants or household bio-waste. The raw material, essentially slurry or sweet corn residues – the “ground material” – is first heated to 70 degrees for one hour, “to remove all pathogenic elements such as avian influenza or other viruses. », explains Matthieu Patalano, operations manager. The biogas produced at this time is recovered via a “pipe”, purified to be suitable for domestic use, and injected in the form of biomethane into the network.

“Digestate” spread in the fields to replace chemical fertilizers

At the same time, the digesters also produce “digestate”, a fertilizer product reused at the end of the chain by 161 farmers within a radius of 50 kilometers, who spread it on their fields, explains Christian Matheu, methane manager of the agricultural and agri-food cooperative group Euralis .

One way to reduce the use of chemical fertilizers, explains Mélissa Coton, a farmer in the neighboring town of Pardies. Recently engaged in the use of digestate, it also hopes to reduce by more than 100 euros the cost price, per hectare, of its cereal production which extends over 200 ha.

Noise pollution and odors worry local residents

The announcement of the installation of a biogas plant in Mourenx, however, aroused opposition among residents of the industrial zone, at the origin of a petition which collected around 700 signatures in 2020. Noise pollution and odors worry them. The TotalEnergies biogas manager ensures that the “acceptability” of the project has been studied: “We have thresholds to respect, so we try to set up in areas where there are already a lot of trucks. »

A treatment unit, costing 500,000 euros, must also eliminate odors. “In France, we have a historical experience with small agricultural methanizers on farms, where everything was done in the open air and where odors spread, but the industrialization of the process now allows us to avoid it”, wants reassure Olivier Guerrini.

From 2021 to 2022, the quantity of biogas injected into the pipes in France has more than doubled, going from 4.3 TWh to 10 TWh; the sector aims to produce 25 TWh of renewable gas in 2025 and 80 TWh in 2030. More than 500 methanizers are now connected in the territory.

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