Gas “Made in Isère”: this is the promise of anaerobic digestion, that is to say the production of gas from organic matter, in particular green waste. This gas is already used in buses in the Grenoble conurbation. “It’s a solution for the future“, estimates this Monday March 14 Christine Gochard, general manager of Gas and Electricity of Grenoble. This solution becomes all the more urgent with the war in Ukraine and the surge in gas prices.
France Bleu Isère – First, explain to us what exactly is anaerobic digestion?
Christine Gochard: Anaerobic digestion is a biological process that occurs spontaneously in nature, in marshes, soils or even in the intestines of living beings (note: cows in particular). Concretely, it is a fermentation of organic matter by bacteria, a digestion. Agricultural waste, manure, waste from the food industry, sludge from treatment plants, etc. can be used. And once this biogas is produced by the bacteria, it must be purified, then it can be injected into the gas network.
What is the role of this energy, this biogas, at GEG today?
Today, we operate the Aquapole wastewater treatment plant in Grenoble. It is one of the first methanization facilities in France, it produces 22 gigawatt hours per year, so it is the equivalent of the consumption of 2,500 Grenoble households. This gives you a rough idea of what methanation produces today in the Grenoble region.
What uses can be made of this biogas? It is used in particular in the buses of the Grenoble metropolitan area…
Absolutely. This biogas, once it is injected into the network, can be used like “classic” natural gas: for heating, for natural gas vehicles – especially in Grenoble -, public transport largely uses natural gas and biogas to run buses in the region.
Can this be a bigger solution? It’s minimal so far…
Anaerobic digestion is a solution for the future, but it is already a solution for today, for the present. At the end of 2021, there were 365 biogas installations in France (note: including 7 in Isère) and it is growing every day. These facilities have a production capacity of 4 terawatt hours, which is roughly the consumption of 500,000 households in France. And there is really a very strong momentum: France is aiming for 100% renewable gas by 2050, with a transition point of ten percent in 2030. And then, all of the current momentum around methanation allows us to say that we is really on the right track.
And how many methanizers must be installed to reach an interesting critical size?
So there, today, I was telling you that there are 365 methanizers installed. But there are more than 1,000 projects that are in development, in discussion with the gas distribution network operators, which are “in the pipeline”, if I can put it that way.
Could this also be a solution to soaring gas prices? We have seen that on the markets, gas prices have increased enormously. Are you likely to pass on these prices to your customers next year?
So, it is certain that at the moment, there is an international context which means that energy prices, and in particular gas and oil, have soared. So we, at GEG, have to manage that directly: we have ten people who deal with forecasting consumption, purchasing energy. Today, there are price shields, whether for electricity or gas. The gas tariff shield was planned until June, but the President of the Republic announced its extension until the end of December.
But overall, it is clear that in this context, anaerobic digestion is a major solution, since it is renewable energy, it allows us to reduce imports and it allows us to reduce the share of fossil fuels.