In Amiens, France, autumn-shed leaves are used to make biogas - just one initiative the city is adopting to turn organic waste into energy, Huff Post reported.
As red-gold leaves start piling upon pavements towards the tail-end of the calendar year, so municipalities are charged with picking them up. In Paris, these leaves are mainly used to produce compost, but Amiens has been able to use them to make biogas - transforming dead leaves into electricity to serve the region's homes.
Isabelle Savariego, vice president of the Amiens Métropole urban community in charge of the environment and biodiversity, said "We try to recover everything that is waste. There are plenty of dead leaves. We said to ourselves: it’s still stupid not to use them."
The city already has a methanation plant that turns other organic waste into energy. "Might as well add the dead leaves. We have to pick them up and do something with them," added Savariego. She said it is important to "produce your electricity, because it is complicated to buy it abroad at the moment."
The transformation process
In 2021, 500 tonnes of dead leaves arrived at the factory. Half of these (the ones that did not need to be cleaned), went to the composting centre, with the other half being treated in the household waste sector. “We remove the glass, a lot of plastic, cups, metal cans. Everything is separated and recovered,” explained Gontran Delamaere, director of the methanation plant.
Once the sheets are clean, the transformation process is launched. “We inject the organic matter from the leaves into digesters, tanks in which there are bacteria. They will degrade the organic matter for three weeks to produce biogas, made up of 55% methane (CH4)", Delamere said. "This biogas, after purification, is recovered on cogeneration engines, to produce at both electricity and heat internally on the plant. The electricity is then injected into the ERDF network."
However, in 2022 the volume is more scarce. "Theoretically, we will have fewer than last year. Spring and summer were dry. There is therefore less plant development,” Delamere continued. Dead leaves only represent a small part of the organic matter used by the plant in the digesters to make biogas - 250 tonnes out of 70-72,000 transformed each year.
On a large scale, supplying an entire city with electricity made solely from fallen leaves seems impossible. According to Delamere, this production can supply the equivalent of just three households. But the total electricity produced by the methanisation plant thanks to all the organic waste together supplies the equivalent of 3,600 homes.
For Delamere, the taxpayer benefits because “the more biogas and energy we produce at the plant, the less it costs the community in terms of treatment costs".
Savariego expressed optimism for future developments: "In a few years, maybe we will have buses that run on biogas."
Amiens, France utilises fallen leaves for biogas production
