First piece of bad news for fans of devices attached to the hindquarters: methane from cows is mainly released through the mouth. It is produced during the fermentation of food in the rumen, one of the chambers of their digestive system, and is then released primarily through belching. In other words, the climate impact of cows has much more to do with burping than with farting. The FAO points out that cattle account for around 75 per cent of global enteric methane emissions amongst all ruminants.
And the quantities involved are by no means negligible. The methane produced during digestion actually represents an energy loss for the animal: according to the FAO, up to 12 per cent of the energy ingested by a ruminant can be lost in the form of methane.
So why not put a mask on every cow and capture its burps?
The idea isn’t entirely crazy. Researchers are already working with mask-like systems capable of measuring the methane exhaled by cattle. For example, a study published in 2026 tested a device combining a mask, a pump, a flow meter and gas analysis to quantify emissions from cows. It is primarily a measuring instrument, not yet a miniature bovine power station, but the principle demonstrates that these gases can be captured.
Research has even gone further. A pilot study published in 2024 experimented with recovering methane contained in the air extracted from around dairy cows, using cryogenic separation. Under their experimental conditions, the researchers achieved very high efficiency in separating methane and producing highly concentrated liquefied biomethane.
Technically, therefore, capturing methane from a cow is no longer entirely the stuff of science fiction.
But there is an obvious problem: a cow is not a factory with a chimney.
It moves around, eats, sleeps, grazes, turns its head and spends part of its life outdoors. Continuously capturing its belches would require equipment that is lightweight, reliable, inexpensive and, above all, comfortable enough not to turn every herd into a brigade of cattle fitted with breathing masks.
And if the necessary infrastructure costs more energy and money than the methane recovered provides, the idea obviously loses much of its appeal.
On the other hand, there is already one place where recovering methane from livestock is much simpler: manure.
When stored under certain oxygen-free conditions, manure also produces methane. This can be captured in digesters to produce biogas, which is then used for heating, electricity generation or converted into biomethane. The technology already exists on a large scale and is probably a much more realistic version of the famous ‘methane collector attached to cows’ backs’.
The idea could even change the way we view agricultural waste. Instead of seeing slurry and manure solely as a problem to be disposed of, they potentially become a source of energy.
The logic is quite compelling: plants capture solar energy, cows eat the plants, their digestive bacteria produce methane, the manure in turn becomes a source of biogas, and some of this energy is then used to power a farm.
A sort of extremely organic circular economy.
But this obviously does not mean that cows will be able to replace French power stations tomorrow. The concentration of enteric methane in exhaled air, the dispersion of the gas, the cost of recovery systems and animal welfare all present obstacles.
To reduce emissions, research is therefore also focusing on a much simpler approach: ensuring animals produce less methane. Diet, herd health, genetics and various nutritional strategies are among the avenues being explored by the FAO and numerous research teams.
Nevertheless, the original idea remains fascinating.
For decades, digestive emissions from cattle were regarded as a kind of biological inevitability: a cow digests, therefore a cow emits methane.
We are now beginning to think differently.
This gas is certainly a climate problem when it is released into the atmosphere. But methane is also… a fuel.
In other words, something we currently regard as pollution could become a small additional source of energy in the future.
And one of the most promising technologies for the energy transition might ultimately stem from a question that no one dared ask at the dinner table:
What if, instead of simply accusing cows of farting, we recovered what they produce?
Although, scientifically speaking, we’d mainly need to fit the pipe to their mouths.
