When the tractor works thanks to cow dung

A few steps from the stable, a farmer from the Dordogne, in the southwest of Francefills the engine of his tractor with methane extracted from excrement of his cowsa way to reduce harmful emissions from the agriculture without giving up breeding animals.

Since its creation in 1926, the Guérin family farm has undergone several changes compared to what was the historic farmhouse with a stone house. The cow barn is largely automated.

Two tanks convert manure into gas, and a service station, with its pump and credit card payment terminal, has recently been installed. Diesel does not come out of the hose, but bioGNV (natural biogas for vehicles), which is cheaper and less polluting, is produced directly on the farm surrounded by walnut trees.

This fuel supplies all the cars on the farm and a new tractor, the first to run on bioGNV, put on sale since last year by the Italian-American manufacturer New Holland.

Bertrand Guérin, 59, hopes that in the near future the company truck that collects his milk will also fill his tank at the farm station. Like the Dutch and British who visit the region, better equipped than the French in gas-powered vehicles.

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

Their fear is that giant companies like Engie and TotalEnergies, looking for alternatives to fossil fuels, “take over the market” linked to methane from agricultural activity.

“Let the peasants develop this trade”cries the farmer.

In all the farms there is methane that is lost

In the vast barn, a Montbéliarde cow addresses itself to the milking robot. Freed – without human intervention – from several liters of milk, she rubs her head under a rotating brush. She then goes through, almost unperturbed, the automatic scraper in charge of evacuating the slurry from the hundred dairy cows on the farm.

The manure and urine from the cows fall into a well and are pumped to the methanizer on the farm.

The straw is also regularly transported to this machine so that, according to the farmer, “there is no time for it to release methane.”

This gas, whose greenhouse effect is much higher than CO2, reduces the carbon balance of cattle farming.

Nearly half of French agriculture’s greenhouse gas emissions are due to methane, either burped by cows or released from their manure.

“In all farms there is methane that is lost”observes Bertrand Guérin.

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

The organic matter is absorbed by the methanizer to ferment at 38º. “It mixes and brews. Bacteria degrade materials and degas CO2 and methane”describes the farmer.

Most of this biogas is burned to run an engine that generates heat and power. Electricity is injected into the grid to supply “to the equivalent of 1,000 families”.

A fraction of the biogas is purified to conserve only the methane, and compressed to produce bioGNV.

At the same time, methane discharges (called digestates) fertilize farm gardens, crops and meadows, partly replacing synthetic nitrogen fertilizers made from fossil gases.

The farm, which has five family members and three employees, aims to get rid of the diesel that the other tractors continue to consume as soon as possible.

(With information from AFP)