A new study out of California suggests a simple fix could make a big dent in methane emissions from dairy farms: just cover manure lagoons with a tarp. Researchers with the University of California, Riverside, tracked methane emissions at a large dairy operation in Tulare County before and after a "digester" system—essentially a sealed cover that traps methane, which is then extracted and burned to generate electricity or converted into natural gas—was installed over its manure pond. The result, per the study published in Global Change Biology Bioenergy: an 80% drop in methane levels, with average concentrations falling from 28.6 parts per million to just 3.7.
"Until now, [these systems'] real-world performance hadn't been verified this rigorously," notes UC Riverside. The process is not without its challenges—installing a digester requires significant investment, there are regulatory hurdles, and ongoing maintenance is required. Indeed, leaks were initially detected at the study site, but they were located and repaired with help from researchers.
But LiveScience provides some numbers from the researchers that indicate just how big a dent digesters could make in California, where livestock manure is the top source of methane emissions. The state passed a law in 2016 aiming to cut methane from dairy and livestock operations by 40% below 2013 levels by 2030. Per the researchers, there are 139 digester projects that were completed or planned in the state as of 2023. If their results align with those of the farm in the study, they would take care of 39% of the 40%. (This content was created with the help of AI. Read our AI policy.)
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