Cow Manure Digesters Effectively Cut Methane, But Leaks Undermine Climate Benefits

UC Riverside study finds dairy digesters are highly effective at capturing methane, but occasional leaks can offset their climate impact.

Mar. 31, 2026 at 12:00am

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A highly textured, abstract painting in soft greens, browns, and blues, featuring sweeping geometric shapes and precise botanical spirals, conceptually representing the complex interplay of methane emissions and manure digester performance on dairy farms.Satellite and airborne monitoring reveal the delicate balance between methane capture and leaks in dairy farm manure digesters.Riverside Today

A new study from the University of California, Riverside has found that systems designed to capture methane from cow manure, called dairy digesters, are highly effective at reducing greenhouse gas emissions. However, the researchers also detected occasional large leaks that can offset the climate benefits of these systems. The study analyzed eight years of satellite and airborne data from 98 dairy farms across California, tracking emissions before, during, and after digester installation.

Why it matters

Dairy farms are a significant source of methane, a potent greenhouse gas, and digesters are seen as a key climate solution to capture this methane and convert it into usable fuel. However, this study shows that while digesters work well overall, the rare but powerful leaks that can occur undermine their environmental benefits. Understanding the performance of these systems at scale is crucial as California continues to invest in expanding dairy digesters as part of its strategy to reduce heat-trapping gas emissions.

The details

The study, published in Environmental Research Letters, found that across the 98 dairies examined, the number of strong methane plumes declined after digesters were installed, suggesting the systems are effective overall. However, the researchers also detected occasional leaks that were far more intense than emissions from traditional manure storage, with some releases reaching around 1,000 kilograms of methane per hour. By comparison, typical emissions from open manure lagoons ranged from 20 to 100 kilograms per hour. The researchers also captured spikes in emissions during digester construction and installation, a phase that is rarely measured but can produce substantial short-term increases.

  • The study analyzed eight years of satellite and airborne data from 98 dairy farms across California.
  • The researchers detected methane plumes emerging from a dairy digester in California on June 22, 2023.
  • The team observed a dairy farm methane plume measured on July 27, 2020.

The players

Alyssa Valdez

A University of California, Riverside climate scientist and lead author of the study.

Francesca Hopkins

A UCR climate scientist who previously led a study examining emissions at a single dairy using ground-based measurements.

University of California, Riverside

The institution that conducted the study on the performance of dairy digesters across California.

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What they’re saying

“I think manure emissions on dairies are underestimated. These digesters seem to be a solution that captures a lot of methane, but I wanted to make sure they were working properly.”

— Alyssa Valdez, University of California, Riverside climate scientist

“For the most part, the digesters are working well. But the few leaks that happen, they make a huge impact.”

— Alyssa Valdez, University of California, Riverside climate scientist

“A farmer might not know their digester is leaking. This gives us a way to detect issues early and prevent them from becoming long-term problems.”

— Alyssa Valdez, University of California, Riverside climate scientist

What’s next

The researchers say satellite and airborne observations are most effective when combined with on-the-ground measurements to provide a fuller picture of dairy farm emissions. As California continues to invest in expanding dairy digesters, close monitoring of these systems will be crucial to ensure they are delivering the expected climate benefits.

The takeaway

While dairy digesters are an important tool in reducing greenhouse gas emissions, this study highlights the need for comprehensive monitoring and maintenance to address the risk of powerful methane leaks that can undermine the climate benefits of these systems. Ensuring the proper functioning of digesters is crucial as California and other regions rely on them as a key strategy to mitigate the environmental impact of the dairy industry.