They have been multiplying on farms across France for several years: lare methanizers. These units produce biogas from animal waste. At a time when the European Union is trying to do without Russian gas, this technology is presented as an interesting alternative.
But some biogas projects are far from unanimous, with opponents who remain mobilized even in summer. This was the case on Wednesday July 20, near Saint-Brieuc. A new rally to protest against the project to install a biogas plant. For them, for sure, this unit will aggravate the problem of green algae. In a few words, a methanisation unit is made up of large tanks where manure and slurry ferment, which produces two things: biogas that can then be reinjected into the network and what is called digestate, these are residues of organic matter.
And it is this digestate that poses a problem for Breton opponents, because it is then used by farmers as fertilizers, enough to normally do without synthetic fertilizers. This digestate must therefore be spread on agricultural land in the bay of Saint-Brieuc. For opponents, it is a real green algae bomb since this material is loaded with nitrogen. And nitrogen is the element that these algae, which have been polluting Brittany’s beaches for years, love. Several municipalities had therefore issued an unfavorable opinion during an initial consultation. Opponents are now awaiting the results of the public inquiry which ended on Wednesday July 20.
Brittany is not the only region affected by these protest movements: in Ile-de-France, Occitanie, Alsace… several demonstrations have been organized in recent weeks. There, the problem is not the green algae, the residents fear the smells, the increase in truck traffic, the risks of pollution. They denounce disproportionate projects. But Brittany, land of pig and cattle breeding, remains the region where the mobilization is particularly strong with calls to rethink the agri-food system.
For’Environment and Energy Management Agency (Ademe) anaerobic digestion is a promising sector with multiple benefits. Source of income for farmers. According to the agency, it has environmental impacts that remain generally positive. However, precautions must obviously be taken, particularly with regard to the sealing of the units.
Since 2011, thanks in particular to subsidies. Methanizers have multiplied across France. There are more than 1,000 today. Of which 400 connected to the gas network. The sector hopes to continue to grow and reach 15% in total gas consumption by 2030. This is equivalent to the share of Russian gas.