Dairy farms reduce climate impact with methane digesters, but communities worry about effects

Home to about 1.7 million cows, California is the country's leading dairy producer and a large contributor of methane. Cow burps and manure emit the potent planet-warming gas. A growing number of dairy farms are using methane digesters to convert manure and other organic waste into biogas to produce electricity or power vehicles. The number is expected to increase since waste management practices such as digesters became eligible for funding from the Inflation Reduction Act—President Joe Biden’s law to combat climate change. In the last decade, about 120 digesters have cropped up across California and roughly 100 more are in the pipeline. But a technology hailed as a cost-effective way to help the state reach its methane reduction goals has become controversial. Industrial-scale dairy farms already are among the biggest polluters in the San Joaquin Valley, a premier U.S. agricultural region with poor air quality. Now residents worry methane digesters could make pollution worse. In the Tulare County town of Pixley, the stench of cow feces, urine and ammonia forces residents to keep windows and doors closed. Some run air purifiers constantly to maintain comfortable and healthful conditions. A study funded by California air regulators recently concluded widespread digester adoption would have minor effects on local air quality. Officials also are looking into whether digesters increase potentially harmful ammonia emissions. Supporters point to the technology’s effectiveness in mitigating climate change. AgSTAR, sponsored by the Environmental Protection Agency and the U.S. Department of Agriculture, estimates manure-based digesters reduced greenhouse gas emissions by more than 10 million metric tons of carbon dioxide equivalent in 2022. That's roughly the annual greenhouse gas emissions from more than 2 million passenger vehicles. Supporters argue biofuel from methane reduces pollution by replacing fossil fuels with cleaner vehicle fuels. Studies have found people living near large dairies can experience fatigue, respiratory problems, burning eyes and runny noses if odors are concentrated enough. And some research suggests digesters can increase ammonia emissions.  This article was provided by The Associated Press.