North Carolina Sees Energy Potential in Pig Poop

But it may not be the solution local communities need to escape the stench and swill of the pork industry.

A farmer on a digestion field where methane is captured at a hog farm in Lillington, North Carolina

Credit: Alex Boerner

Poop happens. And when it happens on farms housing thousands of hogs, it causes major problems.

In North Carolina’s Duplin County, where hogs outnumber humans 30 to 1, an estimated 15,700 tons of manure are generated every day. Hog farmers store the waste in open-air lagoons that produce methane, a potent greenhouse gas. When the lagoons are full, farmers mix the manure with urine to create a liquid fertilizer that’s sprayed on fields. A 2017 study linked this practice to numerous health and environmental threats, which include increased exposure of local communities to airborne pathogens.

The enormous amount of waste also can also run off and contaminate groundwater and waterways. And of course there is the omnipresence of an odor most foul. In fact, the stench from hog lagoons is so strong that a federal jury in Raleigh awarded 10 families living near them $50 million in a nuisance suit earlier this year. (A judge reduced this to just under $3 million due to state laws limiting punitive damages in such cases.)

“One of the most noxious sores on the environment in the state is the swine lagoons and waste lagoons that are famously creating a lot of harm,” says Tim Profeta, director of the Nicholas Institute for Environmental Policy Solutions at Duke University.

North Carolina’s Renewable Energy and Energy Efficiency Portfolio Standard, which passed in 2007, requires utilities such as Duke Energy to generate 0.2 percent of their retail sales from pig power by 2021. So in a $1.2 million pilot project launched just after the standard became law, Duke University partnered with several stakeholders, including Duke Energy, to test the potential for converting methane from hog lagoons into renewable energy.

For this project, an 8,600-head hog farm in Yadkinville, called Loyd Ray Farms, which is still operational, diverts manure to an in-ground anaerobic digester, where anaerobic bacteria feed on the waste and produce methane. A network of pipes then transports the gas to a biowaste converter where the methane, called swine biofuel, is cleaned and injected into the natural gas pipeline. The wastewater is also captured, aerated to reduce ammonia concentrations, and then used to clean the barns. This pilot project, which powers a 65-kilowatt microturbine and produces an estimated 2,500 carbon offsets for Duke University and 3,000 renewable energy credits for Duke Energy each year, shows promise.

Going Whole Hog

In 2015 in Kenansville, Duplin’s county seat, OptimaBio, a Raleigh-based swine biofuel developer, launched a $10 million project dubbed Optima KV. The system involves a digester and a pipeline network connecting five farms with a total of 62,000 hogs; it began operating this past March, capturing sufficient methane to generate 11,000 megawatt-hours of energy—enough for about 1,000 Duplin County homes. Now the company is looking to expand with a second digester, construction for which could start by the end of the year.

Meanwhile, in Bladen County to the southwest, OptimaBio is hoping to start construction in August on a new project, OptimaTH, at a Smithfield Foods processing facility in the town of Tar Heel. Swine gas from that plant could come online as early as 2019—if all the paperwork goes through.

But getting approval from the utilities to use swine biofuel has been challenging. Utilities don’t get paid to take risks,” Mark Maloney, OptimaBio’s CEO, explains. “It’s been a fight to get the project pulled together―not just from an engineering and financial perspective, but also a fight with the utilities to get [swine biogas] into the pipeline system.”

Lipstick on a Pig?

Duke University hoped swine biogas could help it reach its goal of carbon neutrality by 2024, but a proposed pig power plant on campus has struggled to garner support from faculty and students. Many deride the plan as a reinvestment in natural gas infrastructure that would be inappropriate for a university that is a climate leader in other ways. The project is on hold—for now—but Profeta hopes the university can one day incorporate the technology to help meets that climate goal.

Other critics think this fledgling biogas industry does not go far enough to alleviate the bigger environmental problems that communities are facing. Both the North Carolina Waterkeeper Alliance and the Julius L. Chambers Center for Civil Rights have spoken out against the environmental issues associated with massive hog farms in eastern North Carolina. Mae Wu, NRDC deputy director of health and food, calls swine biogas a “false solution that the hog industry is pushing on communities.”

Wu believes there are other technologies, including a process that turns waste into a “super soil” that could be sold as compost and a reactor that converts nitrogen into nitrogen gas that’s released into the atmosphere. But a 2000 agreement between Smithfield Foods and the attorney general of North Carolina doesn’t require solutions to be implemented unless they are technically, operationally, and economically feasible—and so far the trifecta has proved elusive.

Duke Energy is interested in swine biofuel as a method to help meet the state’s renewable energy portfolio standard. Others hope use of swine biofuel would also earn carbon offset credits. But environmental groups, including NRDC, object to such double-counting because it would weaken the overall emissions reductions achieved by these programs.

Duke Energy spokesperson Randy Wheeless believes the viability of swine biogas as a renewable energy source could come down to dollars and cents. Currently, he estimates the manure-based fuel is up to 10 times more expensive than natural gas.

OptimaBio’s Maloney thinks achieving scale―and lowering the cost―is possible. He hopes to build infrastructure to connect as many farms as possible to the grid, vowing to take all of the waste the hogs produce and convert it to swine biofuel.

“The first time you do anything, it costs more,” Maloney says. “I think as the renewable gas industry evolves and develops and grows and consumers start to demand more renewable options, all of the components and technologies and prices will come down and it will become more competitive.”

Even if all of the pieces come together, Wheeless doubts swine biogas will become a significant source of renewable energy in North Carolina. “There is no reason why it can’t be a growing part of the energy landscape,” he notes, “but do I see a time where it’s 10 or 15 percent of the energy mix? No, I don’t see that.”

What many do see, however, is with pig power or not, there will continue be too much pig poo in Duplin County.

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