Duke Energy invests more in pig poop

North Carolina is the second-largest swine producing state.
North Carolina is the second-largest swine producing state. N.C. PORK COUNCIL

Duke Energy has signed a second deal to turn swine waste from farms in Duplin County, North Carolina’s pork capital, into electricity.

The project will capture methane gas from the waste and inject it into natural gas pipelines that serve power plants in Wayne and New Hanover counties. It’s expected to start operating by mid-2017.

This is the second poop-to-power project Duke has announced this year. In March, the company said it would partner with Carbon Cycle Energy to use gas from swine waste at four power plants in North Carolina.

Duke is interested in pig waste because North Carolina’s green-energy mandate requires utilities to use it in making a small fraction – 0.2 percent by 2021 – of their electricity. The state is the second-largest swine producer, after Iowa.

Duke does not expect to meet the mandate’s swine target for this year, but will in 2017 when the new projects start up. The company might have more partnerships in the future, spokesman Randy Wheeless said.

“We’re talking to people,” Wheeless said. “We’re thinking more projects will come online.”

Swine waste is already being turned into energy at six locations in four N.C. counties, said Angie Whitener Maier of the North Carolina Pork Council.

“There are several other projects in various stages of development,” she said, including two that are waiting for connection agreements with utilities.

Some developers are experimenting with technology that uses high heat to turn swine waste into gases that can fuel a power plant, Maier said.

Duke’s strategy is to capture methane, a gas that wafts from covered waste pits called lagoons. Natural gas is mostly methane. The methane from pigs is piped to a central site, cleaned and then sent into natural gas pipelines.

In that way, Duke earns credits that help it meet the N.C. green energy mandate. The company says the process releases less carbon dioxide, a gas linked to climate change, than if the swine waste decayed naturally.

Optima KV will build Duke’s Duplin County projects. Duke expects the gas produced to generate about 11,000 megawatt-hours of electricity annually, enough to power about 880 homes for a year.

Bruce Henderson: 704-358-5051, @bhender