‘Cow Power’ Goes Dark as Manure-to-Electricity Fizzles

August 31, 2022

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by Marc Heller (E&E News/Climatewire) After almost two decades making power from manure, Jon Patterson is done. The electric generator he installed on his dairy farm in upstate New York’s Finger Lakes region in the late 2000s sits idle while he contemplates more promising ways to make money from the back end of a cow. Patterson’s problem: Despite promises that farmers could make a windfall from selling electricity to utility companies, dairy farmers in New York are paid so little for the power they generate from manure that they can’t afford to maintain the digesters and related systems they put in years ago.

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The U.S. has 317 anaerobic digesters operating on farms, according to EPA. The number grew during the 1990s and the first decade of the 2000s but leveled off from 2014 until last year, when the number ticked up again due to interest in renewable natural gas, EPA said.

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Most farmers can't make money at the current low rates, Serfass (Patrick Serfass, executive director of the American Biogas Council) said. "We can blame the fracking of gas for maybe all of that."

Serfass and other supporters say they're optimistic about another product, renewable natural gas, which is more lucrative for farmers and can be either piped from farms or put on trucks in compressed form for shipping. And on-farm electricity production could be revived if EPA takes action under the federal renewable fuel standard to reward "cow power" that's directed toward electric vehicles.

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The idea made sense to farmers who were eager to cut down on manure odor complaints from neighbors. They were willing to try something new and expensive as long as the state paid some of the upfront cost.

Patterson was one of them. So was Jon Greenwood, a longtime farmer in the northern New York town of Canton, about 20 miles from the Canadian border.

"I think a lot of them went into it for the odor reason," said Greenwood on his farm. "Manure stinks, there's just no getting around it."

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Digesters work by heating manure to around 100 degrees Fahrenheit, warm enough for bacteria to generate methane gas that can be trapped and used to power an electric generator, which is connected to the regional power grid. Farmers can also convert the methane to renewable natural gas or compressed natural gas for vehicles, or flare it off on the farm, which reduces greenhouse gas emissions.

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Greenwood signed up for the digester and energy project around 10 years ago, at a total cost of about $3.5 million — covered largely through grants and state tax credits. In addition to dealing with manure, Greenwood said there was another incentive: His farm had become so big, he had to use diesel generators to support the fans in the barns because the electric grid couldn't provide enough power.

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Farmers said they didn't expect to make much profit on manure-generated power and certainly nothing to approach milk, their main source of income. But utility companies haven't been very supportive, Greenwood said, adding that he doesn't necessarily blame them for disliking a system that's been imposed on companies.

"They don't control it. It's power that's coming onto their line," Greenwood said. "They aren't helpful at all on this kind of a project."

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(Qingbin) Wang and fellow researchers found that in 2019, anaerobic digesters generated about 1.28 million megawatt-hours of energy equivalent while reducing greenhouse gas emissions by 4.63 million tons of carbon dioxide equivalent. And that's a "very small proportion" of what agriculture could accomplish, they said.

A NYSERDA spokesperson, Theresa Smolen, said the agency has funded upgrades to generators. But at his Adirondack Farms, (Jon) Rulfs is giving up on his. In June, he and Suburban Propane Partners LP announced they'd build a new digester system on the farm to make renewable natural gas. He'll still get the benefit of reducing manure odors and making leftover dry manure solids into cow bedding. READ MORE

Economic feasibility of converting cow manure to electricity: A case study of the CVPS Cow Power program in Vermont (American Dairy Science Association)

Natural gas could power new chapter in manure-to-energy: Let down by electric utilities, farmers bet on natural gas as a more promising way to make a return from cow manure. (E&E News/Climatewire)

Massachusetts bill adds biogas to Clean Peak Standard Program (Biomass Magazine)

Methane Capture at Dairies, but the Program May Have ‘Unintended Consequences’ -- Scientists and environmentalists appeal for more data, noting that research on the ammonia emissions from processed manure raises troubling questions about a vital element of California’s climate change strategy. (Inside Climate News)

Excerpt from E&E News/Climatewire: California's low-carbon fuel standard is driving changes in the way farmers like Burroughs turn manure into energy. After years struggling to make enough money from electricity sales to maintain aging generators, Burroughs and other farmers are switching to RNG, which generates credits for California's low-carbon fuel standard program and could give new purpose to manure digester systems that might otherwise go idle. READ MORE

Excerpt from Inside Climate News: Digester companies argue they are providing an essential climate technology that’s ready for deployment today. But scientists told Inside Climate News that a better understanding of the impact of digesters on potentially harmful ammonia emissions is needed as the state centers the technology in its strategy to slash emissions and confront climate change. Today, ammonia mitigation technologies for digesters exist, but the state does not require the digester projects it funds to use them.

Digesters are “one of the most successful ways to mitigate methane emissions,” said Rebecca Larson, an author of the paper published by Wisconsin researchers and an expert in manure management at the University of Wisconsin-Madison. “But sometimes, there’s unintended consequences.”

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Each year, the digester projects installed in the state achieve greenhouse gas reductions comparable to more than 2 million metric tons of carbon dioxide, according to the state. That’s equivalent to taking more than 400,000 gas-powered cars off the road for a year. To reach the methane reductions that California law requires by 2030, the state expects it will need to install more than 200 more digesters.

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On farms with digesters like Bar 20, the digestion process results in two products: biogas and the leftover digestate. While the biogas is captured and piped elsewhere for processing and then sold as fuel, the digestate often sits in an uncovered secondary storage pond until a farmer collects it to spread its valuable nutrients on crops.

At dairies like Bar 20, the length of time that the digestate sits in the pond depends on which crops need to be irrigated, a process that varies by season. When the fertile sludge, sitting in a secondary pond or spread on a crop field, is open to the air, it continues to release trace amounts of leftover methane as well as other pollutants like nitrous oxides and ammonia. READ MORE