“Where there’s muck there’s brass”, so the saying goes. 

A possible £400m/year, in fact, if methane emissions from slurry produced by UK dairy cows was turned into biogas, plus some significant reductions in CO2e emissions to bring down warming. However, that’s based on findings that we may be underestimating emissions from dairy manure management by 4-5 times. Not so good. 

You can read more in this paper, written by Prof Andy Atkins (IFEAA) and our co-lead, Prof Neil Ward (UEA). You can also watch a webinar with Andy and Neil about their research, and access a list of video presentations from scientists, engineers and farmers on methane measurements and scaling up the technology for converting emissions into biofuels. IFEAA has also produced a handy White Paper with lots more figures in a very digestible format. Also check out the Net Zero Methane Hub, which features the Cornish farms where the measurements in the study were taken.  .

💰Turning fugitive methane emissions from UK dairy cow slurry into biogas could be worth £52,000 a year in saved fuel costs to the average farm:

• Methane emissions escaping to the atmosphere from dairy farming may be 4-5x greater than estimated and reported in the UK’s National Inventory submitted to the UNFCCC. That’s according to field measurements from two farms in Cornwall, plus a growing body of evidence from similar studies abroad, including Canada, Denmark, the US and Cyprus. This would mean total methane emissions from UK dairy cows (enteric and manure management combined) would be 429 kt rather than the reported 301 kt, which is 42% higher than reported. Manure management would then make up 46% of all methane emissions from dairy cows rather than the reported 23%.

• However, if these fugitive emissions were converted to biogas and farmers used this on farm, methane emissions from UK dairy cow slurry could be worth more than £400m/ year to the sector, or around £52,000/ year to the average-sized UK dairy farm, in saved fuel costs, based on current forecourt prices. For an average-sized herd of 140 cows, this would have the same energy potential as 33,055 litres of diesel fuel/ year.

🌍Using biogas from methane, instead of diesel, could save around 4.5m tonnes of CO2/ year and generate income from carbon credits:

• Commercial technologies are already available to capture slurry lagoon methane, which can then be used to fuel vehicles or generate electricity, reducing the warming impact of methane by a factor of 28 or more than 96%. 
• Turning methane from slurry emissions into biomethane would save the UK around 4.5m tonnes of CO2 emissions/ year (or around 3,000 tonnes of CO2e per farm in the first year) – this could be worth an estimated £191m/ year in carbon credits to the sector, at current carbon prices. 
• Capturing the emissions from manure management of the EU dairy herd would represent a saving equivalent to 5.8% of the remaining global temperature rise budget if temperature were to be kept to 1.5 ◦C of warming.

🐄Emissions from manure management are a ‘missed opportunity’ to tackle warming:

• Tackling methane emissions from manure management should receive much greater attention, since this latest research shows that methane emissions directly from cows (enteric) and from manure management may be roughly equal. Most research has so far focused on enteric emissions, both nationally and internationally, because of the belief that the majority of dairy methane emissions come from enteric sources. 

• The current focus on enteric emissions is leading to missed opportunities. Technology exists to capture and convert emissions from manure management , which would reduce the accumulation of GHGs in the atmosphere and slow rates of global warming.

🚜Technology already exists to capture and convert methane and is being piloted on farms:

• Technology already exists to cover slurry storage facilities with air-tight covers and capture the methane for processing and use, at large and smaller scales, while a methane-powered tractor was launched in 2021. 

• Cornwall County Council is sponsoring six farms to participate in a biogas processing trial. The captured fuel is used to power local authority vehicles. This also reduces local air pollution from ammonia emissions and improved slurry management and reduced need for manufactured fertilisers.

🤓The IPCC’s method for calculating methane emissions may not be robust:

• The findings in this paper suggest that the IPCC framework used by countries, including the UK, to calculate methane emissions from farming, may not be robust: The UK uses the IPCC’s ‘Tier 2’ method – a calculation based on a national set of data related to its herd, management practices, and climate. But this method is based on a small set of studies from the 1990s and 1970s that are coming under increasing scrutiny from scientists. 

• Field measurements in the UK, Canada, Denmark, the US and Cyprus, all point to the Tier 2 method underestimating emissions from manure management. There also appears to be a wide variation in the reported methane emissions from manure management between different countries with similar systems and climates. 

💡Urgent research into manure management is needed, supported by investment and regulation to unlock biogas opportunity. Recommendations:

• Urgent and systematic research into methane emissions from manure management under different geographical and environmental conditions. 

• An incentives framework for capital investment on farms, coupled with regulation, to unlock the potential of existing technology to capture, process and use methane. 

• Research on the obstacles and barriers faced by farmers to adopting these technologies, and how they might best be overcome.