Measuring methane

Professor Euan Nisbet.

Jersey is being used as a ‘test bed’ for vital scientific global research into greenhouse gases. Cathy Le Feuvre visited a local farm to find out why the experts had set up measuring equipment in a cow shed

When it comes to methane there are few people who know more than Professor Euan Nisbet.

As the Foundation Professor of Earth Sciences at Royal Holloway, University of London, he’s one of the world’s leading experts in the field of greenhouse gases, which are known to be main drivers of climate change.

For more than 30 years scientists have been researching greenhouse gases and it’s that study that brought Professor Nisbet and a team of experts to Jersey and to Cowley Farm in St Saviour, in November 2021.

Cowley is home to farmer Andrew Le Gallais, who’s also the chairman of the Jersey Milk Marketing Board. The JMMB invited Professor Nisbet to the Island to help the local dairy industry understand more about local greenhouse gas emissions - and specifically methane - from Jersey cattle. ‘Methane is the second most important greenhouse gas,’ Professor Nisbet explained.

‘It’s in the air for nine to ten years, and it comes from many different sources. The biggest sources are environments like natural wetlands; then there are fossil fuels, natural gases, coal, and also agricultural sources - and cows in particular.’

‘With any sort of ruminant, the methane comes out of the front end of the cow. They breathe it out! Cows are like a walking tropical wetland. If you imagine somewhere in the Congo forest where you get a wetland that is about 37 degrees – that’s a cow! All the cow has done is to internalise the wetland … it does a very good job in digesting grasses as a result.’

Measuring methane and other gases is vital to build up a global picture of emissions, which will ultimately help us understand how we might deal with greenhouse gases.

He continued: ‘Ordinary air that blows in from the Atlantic is about two parts per million methane… if you have a million litres of air, two of those litres would be methane. It’s not worth taking the methane out of that. You’d spend so much energy getting the methane out that your greenhouse gas emission from the energy used would be much worse.

‘But once you get up to about one hundred parts per million, then it’s probably worth destroying the methane. You can essentially burn it into carbon dioxide and water. CO2 is far less warming than the methane … methane is so much a stronger greenhouse gas.’

State of the art equipment, including pipework and an extraction unit, was set up in the centre of the cowshed at Cowley Farm where most of the ‘rumination’ takes place when the cattle are there.

‘In the middle of a cowbarn you get air that’s one hundred parts per million or more of methane, so it may be worth taking that air and putting it through something that destroys the methane,’ Professor Nisbet explained.

Tests were made in sheds, on manure and on slurry being spread on fields, and the scientists also took to the road. The Royal Holloway academic team also came with a vehicle specially fitted with incredibly accurate measuring equipment and a GPS receiver. Touring the Island, the air was sampled to identify different methane sources as well as co-emitted gases, including ethane and carbon dioxide.

Dr James France of Professor Nisbet's research team, measuring methane. “ With any sort of ruminant, the methane

comes out of the front end of the cow. They breathe it out! Cows are like a walking tropical wetland. If you imagine somewhere in the Congo forest where you get a wetland that is about 37 degrees – that’s a cow!

Mapping different methane sources according to their carbon isotopes allows the scientists to determine whether methane is coming from cows, or gas or other sources. It’s effectively a ‘chemical fingerprinting’ of the methane in the air.

‘Jersey is a very good natural laboratory,’ Professor Nisbet said. ‘There’s wind coming in from the Atlantic and if you drive around Jersey, you can identify all of the gas sources because it’s not just cattle, there’s also gas use in Jersey as well as sewage and waste burning and so on … we can pick up all of that.’ The results of the Jersey research will eventually be written up as academic papers which will become part of the wider understanding of greenhouse gases not just here in the Island and in the UK, but also across the globe.

Results will also be fed back to the JMMB and Andrew Le Gallais and to the wider Jersey farming community, which is very conscious of the global debate around the impact of the dairy industry and greenhouse gases produced by cattle.

‘We do want to understand how different diets might affect the production of methane, and how we might be able to control methane emissions especially when our cows are housed during the winter months,’ Andrew said.

‘The really exciting part of our relationship with Euan and his team from Royal Holloway is their enthusiasm to use our Island as a valuable test bed for their research. Controlling greenhouse gas will increasingly dominate all our lives in the years ahead, and I passionately believe that we owe it to our unique Jersey Cow, to make sure that she is not unfairly represented.’