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

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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.

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[Cows getting ready to be milked at Wickstrom Jersey Farms]

[Cows getting milked on rotating platform]

Brent Wickstrom (interview): “This is Wickstrom Jersey Farms. We milk about 2,500 cows here. Since 1973, we shipped to Hilmar Cheese. All our milk is produced into block cheese products.”

[Cows standing in water flushing out manure to lagoons]

[Cows in covered pen]

[Wickstrom walking on dairy digester capturing gas from lagoon at Wickstrom Jersey Farms]

Brent Wickstrom (interview): “But while it’s in there, the plastic cover is capturing all the methane that that manure liquid emits. So instead of going into the atmosphere, it’s captured, and sent in a pipeline about 20 miles to their ethanol plant.”

[Dairy digester]

[Wickstrom walking on dairy digester]

[Macias and Wickstrom standing next to uncovered lagoon on dairy farm]

[Machine separating out solids from manure]

[Dairy digester on dairy farm]

[Aemetis ethanol biogas processing plant]

[Aemetis biogas facility that processes methane from nearby dairy farms]

Rob Macias (interview): “In the last 5 to 7 years, companies like ourselves have come in, worked with the dairymen, resolved their methane mitigation issues, and then also provided them with the revenue stream.”

[Plant processing digester gas]

[Dairy digester on dairy farm]

[Cows on dairy farm]

Leslie Martinez (interview): “This isn’t like a small mom-and-pop firm. This is thousands of cows that are living next to people. A cow is producing waste, and we are incentivizing this waste to be produced next to poor communities.”

[Calgren ethanol and biogas facility that processes methane from nearby dairy farms]

[Beverly Whitfield eating lunch with friends]

[Beverly Whitfield stands in her backyard]

Beverly Whitfield (interview): “We don’t need any more cows here. Our town is not big enough for no more cows. We got enough cows here, and they pooping and everything else. And we smelling the poop and all that. I think we’ve had enough poop for a while.”

[Maria Arevalo demonstrating respiratory she wears at night to treat sleep apnea]

Maria Arevalo (interview): “Please help us, help us to breathe better air in Pixley and our communities around here.”

[Digester on dairy farm]

Michael Kleeman (interview): “So the bottom line conclusion about dairy digesters in California is that they don’t significantly impact the air pollution that we experience.”

[Dairy digester on Wickstrom Jersey Farms]

Michael Kleeman (interview): “I do believe that the dairy digesters in the form that they’re being used are a net benefit in reducing greenhouse gas emissions.”

[Cows in pen at Wickstrom Jersey Farms]

This script was provided by The Associated Press.

The related lesson for this video will be published next Tuesday.