Since its creation in 1926, the exploitation of the Guérin family has changed a lot around the heart of the historic stone farmhouse.

The cow barn is largely automated.

Two semi-buried tanks with rounded dome convert their dung into energy.

And a dark green gas station has just sprung up below, with its pump and bank card payment terminal.

At the end of the pipe, no diesel, but bioNGV (natural biogas for vehicles), cheaper and less polluting, produced directly on the farm surrounded by walnut trees.

This fuel powers all the farm's cars and a new tractor, the first to run on bioNGV, put on sale last year by the Italian-American manufacturer New Holland.

In the near future, hopes Bertrand Guérin, 59, the company truck that collects his milk will also fill up on site.

As well as the Dutch and British visiting the region, better equipped than the French in vehicles running on gas.

Farmer Bertrand Guérin uses a biogas service station in Beaumontois-en-Périgord, February 14, 2023 © Philippe LOPEZ / AFP

The station displays the Biogaz de France brand, created by the Association of Methanizer Farmers of France (AAMF), of which Bertrand Guérin is vice-president.

His fear: that giants like Engie and TotalEnergies, in search of alternatives to fossil fuels, "seize the market" linked to methane from agricultural activity.

"Let the peasants develop this profession", pleads the 59-year-old breeder.

"We mix, we brew"

In the vast barn, a Montbéliarde goes by herself to the milking robot.

Relieved, without human intervention, of several liters of milk, she rubs her head under a rotating brush and relieves herself.

Then she straddles, almost imperturbable, the automatic scraper responsible for evacuating the manure from the hundred or so dairy cows on the farm.

Dung and urine cascade into a well and are pumped to the farm's methaniser.

The cows' straw bedding is also regularly sent to this digester so that this manure does not have, according to the breeder, "no time to release methane".

Cows photographed in the Guérin family barn in Beaumontois-en-Périgord on February 14, 2023 © Philippe LOPEZ / AFP

This gas, which has a much higher warming power than CO2, weighs down the carbon footprint of cattle farming: nearly half of the greenhouse gas emissions from French agriculture are due to methane - whether belched by cows or that emerges from their manure.

"In all livestock farms, we have methane that is lost", observes Bertrand Guérin.

To improve its carbon footprint and spend less, it transforms this source of pollution into fertilizer and fuel.

Every day, 40 tonnes of organic matter (two-thirds manure/slurry, one-third waste from the food industry) are engulfed by the methanizer to ferment at 38 degrees.

"We mix, we brew. Bacteria degrade the materials and degas CO2 and methane", describes the farmer.

Most of this biogas is burned to run an engine that generates heat and power.

The electricity is injected into the network to supply "the equivalent of 1,000 families".

A fraction of the biogas is purified to keep only the methane, and compressed to make bioNGV.

Bertrand Guérin examines the control panel of a generator powered by biomethane in Beaumontois-en-Périgord on February 14, 2023 © Philippe LOPEZ / AFP

At the same time, the discharges from the methanizer (called digestate) will fertilize the orchards, crops and meadows of the farm, and partly replace synthetic nitrogen fertilizers, made from fossil gas.

The operation, which has five family partners and three employees, intends to free itself as soon as possible of the diesel fuel still consumed by the other tractors.

For this almost century-old farm, enthuses the breeder, "it's completely the beginning of the story".

© 2023 AFP