By flushing your toilet in the Valence Romans conurbation, you are now producing biogas. A methanation unit built in the Mauboule district makes it possible to recycle almost all the sludge from the wastewater treatment plants in Valence, Romans – sur Isère and Portes-lès-Valence: 4,500 tonnes of materials per year which were previously incinerated. The sludge from Portes-lès-Valence arrives at the Mauboule site via a pipeline of more than 4 kilometers. Those of Romans are transported by truck.
The sludge is heated in a tank at 35° for 3 to 4 weeks. This fermentation produces gas, which is stored in a large balloon, then filtered, purified and injected into the GRDF network (from August; for the moment, the unit is still in the running-in phase). Interesting for the environment and to depend less on foreign gas: “wastewater, we produce it every day, its quantity increases with the population” underlines Pierre Ribaute, general manager of the water activity at Véolia, “rather than considering them as waste, we consider them as a renewable resource. And with the context of very volatile energy prices, producing gas locally becomes an issue.”
– Nathalie Rodrigues
Enough to heat 7,000 inhabitants
The Mauboule methanisation unit cost 11 million euros, with significant aid from the Water Agency. It roughly produces enough to heat 7,000 inhabitants: “7,000 inhabitants every day for at least 30 years, because it is a station that has a lifespan of at least 30 years” indicates Nicolas Daragon, president of Valence-Romans Agglo, “There, that means something, especially in this period when our dependence on fossil fuels must decrease, because we no longer have enough of them, because they create CO², greenhouse gases, and then because that prices are exploding and that the purchasing power of our fellow citizens will not support it, like that of local communities elsewhere.”
The State wants to develop methanisation. Elodie Degiovanni, the prefect of Drôme, will hold a meeting in the fall to raise awareness among local authorities. Its services have already drawn up a framework document to support project promoters.
– Nathalie Rodrigues