French village heats school with walnut shells, saving €9,000 annually

A small village in southwestern France is using walnut shells as fuel to heat its school and municipal buildings, cutting costs and reducing waste, reports Swedish public broadcaster SVT.

In Sainte-Mondane, what was once considered agricultural waste is now a resource. Workers carefully sort walnut shells—previously discarded—to use as biomass fuel in a shared heating system. The process involves emptying and cleaning the shells before transporting them to a boiler that supplies heat to the local school, community hall, and government offices.

Lucilia Goncalves, who sorts the nuts, explains the meticulous process: “The important thing is to empty the shell completely, ensuring nothing remains inside and that it’s clean. You have to be thorough and patient.”

The initiative has already delivered financial benefits. Mayor Gilles Arpaillange estimates annual savings of around €9,000, funds that can now be redirected to other community projects.

Meanwhile, researchers are exploring further uses for walnut shells, including converting them into electricity, as part of broader efforts to repurpose agricultural byproducts in the energy transition.