LMethanization is a process of decomposing organic matter to transform it into biogas. To put it simply, Christian Dolheguy, one of the two brothers who took over the family farm located in Came, explains it in a few words: “It is a reproduction of the cow's stomach”.
More concretely, Frédéric Soulier, GRDF director of the Pyrénées-Landes territory, compares the energy produced by biogas to that of wood. “In the methanization process, we start by recovering organic waste such as manure, slurry or plant substrates. » This step therefore makes it possible to capture CO2.
The elements are then stored in a tank closed by a tarpaulin called a digester which will heat the raw material to recover the biogas. It will subsequently be consumed by households and industries. “As when burning wood, the quantity of CO2 released is almost equivalent to what was previously absorbed, which produces a very interesting carbon footprint,” concludes Frédéric Soulier.
Crop residues from the agricultural operation are stored on the methanization site.
Juliette Grall / “SO”
Energy autonomy and decarbonization
While only what evaporates is used to produce this biogas, what should we do with the rest of all this unused organic matter, called digestate? This is the second interesting aspect of methanization. “98% of this digestate is spread across our 250 hectare fields to replace chemical fertilizers,” explains Christian Dolheguy. We even have to buy additional raw materials from other operators to meet the volumes. »
The two brothers are pleased with the productivity of such an enterprise, “today, our farm covers, on average throughout the year, 60% of the energy needs of households in the canton of Peyrehorade,” continues Christian Dolheguy, “and the needs in fertilizer for our crops are fully covered.” Enough to set an example in terms of energy autonomy and decarbonization.
Income as a motivation
The main motivation that pushed these two brothers to embark on such a project was to diversify the farm's income. “We started thinking about it in 2019.” After the continued increases in the price of livestock, Christian Dolheguy did not escape the numerous losses of his herd due to bovine tuberculosis. He states today that “biogas production represents around a third of [nos] income”.
The installation of these infrastructures required an investment of 3.5 million euros, subsidized up to 23% by the region and Adem (Environment and Energy Management Agency). GRDF, for its part, intervenes in the control of the quality of the gas which is subsequently resold to the Save Énergie company.
Anaerobic digestion meets the objective set by the Region of reaching 30% biogas production across the entire neo-Aquitaine territory in 2030. Today, the percentage is around 6%, which still leaves a lot way to go. The Pyrénées-Atlantiques department has eight methanization sites, including seven in Béarn.
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