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By Catherine Clabby, NC Health News
Good news about hog waste can be scarce in this swine-rich state.
But success at converting swine waste into usable renewable energy seems to be gaining steam.
For the first time, this year a bioenergy project in hog-packed Duplin County injected natural gas harvested from hog farms into a commercial pipeline. Duke University now wants to use North Carolina hog-sourced biofuel, rather than natural gas, to fuel its campus steam plants.
“The opportunities are extremely significant. North Carolina is known as the third richest biogas resource state in the country,” said Gus Simmons, director of bioenergy at Cavanaugh & Associates, the engineering firm that designed the Duplin County site. “North Carolina has such richness because of agricultural production in our state.”
But some neighbors to big hog farms who have lived with odors and coped with the consequences of hog waste disposal for years say harvesting energy at these farms is not enough to decrease their environmental health impacts.
Government and industry should ensure changes at concentrated animal feeding operation (CAFO) farms to produce bioenergy should also reduce risks of air, soil and water pollution, they say.
Several people brought that very message in person and in writing to the most recent meeting of the state Energy Policy Council, which advises the governor and state legislators on domestic energy matters.
A NC native gas?
Interest in producing renewable fuel from farm waste, landfill trash and even human sewage is growing globally.
Part of the appeal is that the process harnesses a natural process. To feed themselves, microorganisms that thrive in environments lacking oxygen digest organic waste to extract energy. These dining microbes produce methane gas as waste.
Methane is the primary component of natural gas. When produced on a farm, it can power equipment where it is produced, say lighting or machinery. Or it can be exported off the grounds, by truck or by pipe, including into a natural gas pipeline.
Some 75 biogas systems are already up and running at landfills, municipal wastewater treatment plants and farms in North Carolina, according to a draft 2018 Energy Policy Council report, which describes big potential for biogas production in this state.
Producing hog-sourced bioenergy would not only lessen emissions of the potent greenhouse gas methane at North Carolina farms, advocates say. It could make or save money for farmers and spawn jobs in the eastern part of the state, a rural region hungry for work.
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When it comes to #piggas, as many tag this topic on social media, there are added incentives. The state’s Renewable Energy and Energy Efficiency Portfolio Standard created in 2007 requires power utilities to include hog-sourced bioenergy as 0.2 percent of their retail electricity sales by 2021.
To date, progress has been slow to develop that unique quota due to a lack of supply. But recent engineering progress on display at the Duplin site and elsewhere may make using some of the estimated 8.7 million tons of manure produced by 9 million hogs to make biogas.
Waste to energy
At nearly all 2,200 of North Carolina’s large hog farms, manure gets washed from pits below confinement barns into open-air basins called lagoons, where microbes already decompose some waste. To make room for more hog waste, farmers periodically spray lagoon liquid onto fields near their barns.
If not managed properly, lagoons can stink and their contents can spill into waterways, shortfalls documented by researchers at N.C. State University and elsewhere. A New York-based researcher said DNA tests he’s used have detected particles of hog feces that floated from farms to neighboring homes.
Those complaints have created big conflicts with neighbors and environmentalists here for decades. Very recently neighbors and their allies gained ground with two recent lawsuit wins in federal court and in a federal civil rights complaint settlement with the state Department of Environmental Quality.
Now they want a say in how this state treats farm-to-biogas projects.
Energy & environment?
In the the Optima KV project in Duplin, County, the first to feed a pipeline here, five farms are flushing hog waste into covered anaerobic (oxygen-free) digesters. The resulting methane gets cleaned some on the farm and then piped to a recently built hog biogas refinery nearby, where it is purified until nearly 100 percent methane.
Smithfield Foods, individual hog farmers, Cavanaugh & Associates, and investors have financed the project. And Duke Energy has agreed to buy gas, which will likely help the utility meet this state’s requirement, the only one in the country, to use hog biogas.
Liquid waste left behind on the farms gets stored in their open lagoons until it gets sprayed on fields.
But some swine waste biogas systems take extra environmental clean-up steps, said Will Hendrick, an attorney with the Waterkeeper Alliance, which has been active in recent challenges to environmental impacts from hog farms.
“We could support waste-to-energy that uses environmentally superior technology,” he said.
The North Carolina Environmental Justice Network “supports exploring waste-to-energy projects that meet the standards and “benefit the communities impacted by CAFOs,” said Elizabeth Haddix, a lawyer with the Durham-based Julius L. Chambers Center for Civil Rights.
A Duke University project at Loyd Ray Farms in Yadkinville, Hendrick noted, takes steps to both make methane and clean up the liquid waste still left behind.
The system, also designed by Cavanaugh, treats liquid waste after methane production in an aeration basin, similar to those used at wastewater treatment plants. That step removes pathogens, metals and nutrients such as nitrogen and phosphorus that can fuel excessive algal growth in waterways.
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That approach meets “environmentally superior” hog waste management standards North Carolina has required for any new large hog farm in this state since 2007, Hendrick said.
“I think it’s really important that we find ways to make biogas projects work for the communities where they they are based,” said Tanja Vujic, director of biogas strategy at Duke. “They should just as much work for farmers and work for the environment.”
At the recent state Energy Policy Council meeting, Jamie Cole from the North Carolina Conservation Network and others asked energy policy council members to remember hog farm neighbors when evaluating the promise of hog biogas.
Their pleas seemed to have an impact.
Jennifer Mundt, energy director for the state Department of Environmental Quality, suggested that council members revise their nearly completed 2018 draft recommendations to Gov. Roy Cooper and legislators regarding biogas.
Council members could recommend analyses of environmental and community impacts and benefits of biogas harvesting, as well as an economic impact analysis already endorsed in the document, Mundt said.
Without debate, council members agreed.
Their final report should be submitted to Gov. Cooper and legislators by the end of this month, Mundt said Monday. A copy will be made public immediately after that.