Methane is an extremely potent greenhouse gas, capable of trapping more than 80 times as much heat as carbon dioxide over a 20-year period. Indeed, it is thought that between 20 and 30 percent of global warming since 1750 can be pinned on methane emissions alone, and agriculture is one of the biggest culprits.
But it is possible to capture and cleanse methane before turning it into a product that can be reused, as one family farm in California has shown. The implementation of dairy digesters could reduce methane emissions by approximately 80 percent, say climate researchers writing in Global Change Biology Bioenergy.
“When the system is built well and managed carefully, the emissions really drop. That’s what we saw here,” lead author Francesca Hopkins, a climate scientist at the University of California, Riverside, said in a press release.
Dairy Cows and Methane Emissions
Dairy cows are one of the largest sources of methane emissions in the state of California. Some of this is an unfortunate by-product of the animals’ burps and farts, but a large volume is produced during the manure storage process.
This is because manure is frequently kept in open, water-filled pits where it decomposes without oxygen and releases methane into the atmosphere. According to the study, these are the largest single source of methane emissions in the state’s inventory and contribute to around 54 percent of the methane emissions associated with the dairy sector.
Read More: Cleaning Up Cow Burps To Combat Global Warming
Turning Emissions Into Fuel
However, that could change with the effective deployment of dairy digesters – essentially, manure ponds that have been sealed with air-tight membranes that prevent any gas from escaping. Trapped methane can be cleaned and repurposed as renewable natural gas, which then can be used as a substitute for diesel in long-haul trucks. There are more than 130 such systems in place in dairy farms across the state, but their effectiveness has not been thoroughly studied until now.
To fix this, researchers at the University of California, Riverside, compared emissions at a dairy farm in Tulare County before and after dairy digesters were installed. The results suggest the addition of dairy digesters can reduce overall atmospheric methane emissions by 82 percent.
As the authors in the study note, it was not entirely smooth sailing. The researchers did detect leaks in the system. But once these cracks had been pointed out, the issues were resolved, and reductions in methane subsequently followed.
“This was a textbook case of adaptive management,” Hopkins said in a press release. “The partnership between scientists, the company, and the farmer really made a huge difference.” Adding, “But this is a real example of cooperation that leads to measurable results.”
Moo-ving forward
According to the United States Department of Agriculture, there are approximately 87.2 million cows currently being farmed in the U.S.. This includes more than 9.3 million dairy cows.
The researchers admit costs may be prohibitive for many – dairy digesters require significant investment, both in terms of money and upkeep. It is also worth noting that they do not account for many other emissions (like ammonia) that are common to dairy farming.
What’s more, renewable natural gas is not without its own controversy or accusations of greenwashing. Yet, the study’s authors say adopting these measures can be a cost-effective method of slashing methane emissions, supporting the state’s efforts to cut total emissions by 40 percent below 2013 levels in the next five years.
“They’re not for every farm,” said Hopkins in the release. “But for dairies that can make it work, this is one of the most cost-effective ways we have to cut these greenhouse gas emissions.”
Read More: Argentina Could Promote More Climate-Friendly Livestock Production
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Global Change Biology Bioenergy. Anaerobic Digester Installation Significantly Reduces Liquid Manure Management CH4 Emissions at a California Dairy Farm
World Resources Institute. 7 Things To Know About Renewable Natural Gas
Rosie McCall is a freelance writer living in London. She has covered science and health topics for publications, including IFLScience, Newsweek, and Health.
