In-state hog farms are increasing the state’s supply of RNG
DUPLIN COUNTY—A Duke Energy power plant is using renewable natural gas from North Carolina-based hog farms to produce electricity—the first use of this technology at in-state farms.
“This is a major breakthrough for renewable energy in North Carolina,” said David Fountain, Duke Energy North Carolina’s president. “This project allows for the capture of emissions from hog operations and converts the RNG to electricity for customers.”
“North Carolina has a large hog population,” Duke Energy spokesman Randy Wheeless told American Gas. “And hog waste is stored in open lagoons. The methane was just escaping into the environment. I think there was a lot of momentum in the state to see if we could dampen the environmental impact of that.”
The Duplin County project, known as Optima KV (due to Duke Energy’s partnership with OptimaBio), captures methane gas from the swine waste of five local farms. Using more than 42,000 feet of in-ground piping, the methane is moved to a central location where the gas is cleaned and converted to pipeline-quality natural gas. The RNG is injected into the Piedmont Natural Gas system and transported to Duke Energy’s Smith Energy Complex in Richmond County, where it is used to produce electricity.
“Biogas is such a rich resource for the state, especially for North Carolina’s agriculture industry,” said Gus Simmons of Cavanaugh & Associates, an OptimaBio partner. “Harvesting unused organics such as swine manure from farms can create a new business opportunity for farmers, provide an in-state source of energy fuel, and improve the sustainability of the agriculture and energy sectors. It’s a win-win.”
While it is not unusual for states to export their RNG or sell it for credits, North Carolina has no such plans, even if the project expands. “We’re taking the total output of that project, no matter how large that project turns out to be,” Wheeless said.
Historically, RNG has been used by smaller, on-site generators connected to the overall energy grid. Duke Energy’s larger, more efficient plants allow more energy to be created with the same amount of RNG. The project is expected to yield about 11,000 megawatt-hours of electricity—enough to power about 1,000 homes.
The project will help Duke Energy satisfy state swine waste-to-energy mandates. By law, the utility must generate 0.2 percent of its retail sales from swine waste by 2023.