Comment Fréjus produces “organic” and local gas which brings in a nice jackpot each year
While the price of gas has been soaring for months and soaring since the war in Ukraine, the community of eastern Var municipalities has been visionary. By looking for solutions for several years and by investing, the Estérel Côte d’Azur conurbation (EC2A) has achieved the performance of creating entirely organic gas.
Not only “green energy”, this gas is therefore local… and does not come from Russia.
It all started when the Var-Estérel-Méditerranée urban community (Cavem in 2015), in a desire to offer its energy dependence, asked Veolia to find a process that would reduce the mountains of sludge produced by the treatment plant. of Reyran.
An exemplary physico-chemical and biological plant which treats the territory’s ten million cubic meters of wastewater every year. Its main waste, sludge, residual sediments, are not incinerated but are composted to improve the land.
35% less sludge to evacuate
Philippe Chaniol, engineer, then proposed an innovative solution. So much so that the call for projects and the legal texts only came out during the final editing of the file.
“We jumped at the chance. La Cavem had to reduce the 10.00 tonnes of sludge that came out of the factory after the wastewater treatment. I proposed to build a 4,000 m sludge digester3 which could reduce them by 35%. By reducing the volume of sludge to be evacuated by the road network, thus going from 10,000 to 6,500 tonnes per year, transported to make compost, the gain is 400,000 euros”, explains Philippe Chaniol, Project Manager at Véolia.
The second advantage of the digester is the possibility of transforming sludge into energy. Products on the territory, valued as raw materials, transformed on site to produce ecological energy, corresponding to more than 30% of the consumption of the Raphaëlo-Fréjusien sector in summer or the supply of 750 households in winter.
Pure enough for the GRDF network
“The gas passes through membrane filtration, which enriches it and brings the methane to more than 99%. The product comes from biological, non-carbon digestion, which is not captured and does not come from oil”, continues the expert.
The sludge, heated to 37% (as in a belly) by heat pumps which recover the calories from the station’s wastewater (a real virtue), ferments in the digester. Bacteria degrade organic matter.
The recovered methane has the same characteristics as natural gas. “The biogas is pure enough for the injector into the GRDF network. This process won over Cavem, which responded to the water agency’s call for projects and won”, says the engineer.
770,000 m3 of biogas produced in 2021
In 2021, the plant produced 770,000 m3 of biogas. Sold for one million euros. “France wants to develop this system very significantly. But it’s recent. If farmers make it from slurry, this was not the case for wastewater treatment plants. That of Reyran was the first in Paca”, emphasizes the specialist.
“The GRDF network also had to be able to recover the 110 to 120 m3 of gas per hour injected, he adds. GRDF made a direct connection to the station. Their professionals carry out analyzes and checks constantly to check that the gas is compliant. The quality is there.”
Philippe Chaniol is working on other innovations such as a system for bio methane to produce hydrogen.
The digester project in the Reyran station was the 2019 winner of the Green Solutions Awards, an international competition presented in front of buildings, examples of infrastructures contributing to the fight against climate change.