Methane: A Potent Greenhouse Gas with a Hidden Opportunity

While carbon dioxide is the most important anthropogenic greenhouse gas, methane (CH4) is far more potent. This comparatively short-lived gas traps 80 times more heat than CO2 over a period of two decades.

Greenhouse gases are essential for making our planet habitable, but high concentrations of these heat-trapping gases are now raising the earth's surface temperature significantly, leading to global warming and climate change.

While carbon dioxide is the most important anthropogenic greenhouse gas, methane (CH4) is far more potent. This comparatively short-lived gas traps 80 times more heat than CO2 over a period of two decades. According to the UN Environment Programme, since pre-industrial times, methane has accounted for about 30% of climate change.

This second most abundant greenhouse gas is the main component of natural gas and biogas.

Methane is colorless, odorless, and highly flammable. Natural methane is found below the ground, with wetlands being its largest source. It is also found under the sea bed, beneath the Antarctic ice, and in oceans. This gas is also produced by volcanoes as well as the decay of plant and animal matter.

An important contributor to methane's release into the environment is human activities which include landfills, agricultural activities, livestock, manure, coal mining, and oil and gas production.

When emitted into the air, methane reacts in hazardous ways. Not only it releases carbon dioxide emissions through oxidation but also contributes to the forming of the ozone. This way, it decreases air quantity, leading to premature human deaths, reduced crop yields, and causing health issues in animals.

In humans, this potent greenhouse gas can also cause issues like asthma, cardiovascular disease, and increased risk of stroke. Methane gas poisoning, meanwhile, can lead to asphyxiation.

High levels of methane can also cause issues like memory loss, slurred speech, nausea, flushing, headache, vomiting, mood changes, and vision problems. Meanwhile, contact with liquefied methane released under pressure may cause frostbite.

Given the harmful effect of methane, there has been a greater focus on better quantifying and drastically reducing methane pollution to prevent the worst climate impacts.

Methane Emissions from Manure Far Greater

Farm livestock are a prominent source of methane emissions from agriculture. As per the current Intergovernmental Panel on Climate Change (IPCC) estimation, it accounts for 12% to 14.5% of all human-induced GHG emissions.

The national inventories of greenhouse gas emissions meanwhile report that emissions coming directly from the digestive systems of animals (enteric fermentation) are three to nine times greater than those from manure management, including the storing and spreading of slurry and manure. However, the emissions from these two cases could be much closer to 50:50.

According to new research, though, the actual methane emissions from slurry stores on dairy farms could be as much as five times more than what the official statistics suggest.

Conducted by the University of East Anglia (UEA) and a not-for-profit association, the International Fugitive Emissions Abatement Association (IFEAA), the study is based on calculations from two dairy farms in England.

The research suggests the ‘Tier 2' calculations currently being used by countries to report their emissions annually to the IPCC may not be robust, hence the underestimation.

The measurements of emissions from slurry lagoons were analyzed by researchers during 2022-23. To capture methane, airtight covers were used to enclose the slurry lagoons, which showed that they generate far more CH4 than previously suggested.

As per the findings, the actual emission was 145 kg per cow per year on one farm and 198 kg per cow per year on the other farm. This is 3.8 – 5.2 times higher than the existing official figure of 38 kg per cow reported in the UK's National Inventory.

While the standard international methodology seems to underestimate slurry storage methane emissions, the research says that today, we have the technology that can help “turn this problem into a business opportunity.” Methane can actually be easily captured and then used as a fossil fuel alternative, which also creates “an additional income stream for farms.”

Highlighting the huge potential for turning that methane into a renewable energy source, Professor Neil Ward of the Tyndall Centre for Climate Change Research at UEA noted that using methane as a fuel can help farmers reduce their energy bills and become energy independent.

Capturing and turning emitted methane into biogas could save an average-sized dairy farm about £52,500 in fuel costs. In total, this cost saving could be over £400 mln for the dairy sector.

Existing technology can capture the gas, and using it across the EU's dairy herds could cut emissions by an estimated 5.8% of the budget for limiting global warming to 1.5°C, according to research.

The significant underestimation of manure management emissions means that not only are the estimates inaccurate, but priorities regarding reducing options may also be distorted.

“This research therefore represents an urgent call for action and further work to better understand methane emissions from manure management.”

– Prof Ward

So,