Duke Energy has finalized a second deal in 2016 to buy captured methane gas derived from swine waste.

In March, the company announced a project with Carbon Cycle Energy to use swine waste-derived gas at four power plants in North Carolina.

For its newest project, the Charlotte, N.C.-based utility company will partner with Optima KV, a Wilmington, N.C.-based partnership that brings together experts in bioenergy, agriculture, project finance, and environmental stewardship. The project will be located at farms in Kenansville, N.C. -- the heart of Smithfield Foods' pork operations.

The 15-year project will use captured methane gas to generate carbon-neutral renewable electricity at two power stations. Optima KV will construct a digester at each farm and pipe the captured methane gas to a centralized facility where it will be cleaned to pipeline quality specifications and injected into the natural gas pipeline system.

“Duke Energy has been in active conversations with both Smithfield Foods and Piedmont Natural Gas to identify prospective sites for meeting our swine compliance. Over the course of these efforts, five farms were identified as a good cluster for a potential directed biogas project due to their proximity to a physical transportation pipeline,” says Travis Payne, business development manager for Duke Energy.

During these initial discussions, Payne says it became clear technical expertise would be required to make the project a reality. In 2015, Optima KV became a part of the discussions. They are partnering with Cavanaugh & Associates to develop and operate the facility.

“Optima is excited about this partnership with Duke Energy and North Carolina swine farmers,” Gus Simmons, partner in Optima KV and concept designer, said in a statement. “Our on-farm digesters will integrate with and support the farmers' existing operations. By centralizing the gas processing, we can take advantage of cost efficiencies and provide carbon-neutral fuel for Duke's existing power plants. It's a great benefit for the environment and for the economy.”

Optima KV will install digesters at five farms for waste handling and biogas production to collect and pipe-dry biogas to a central location for cleaning and injection into the natural gas pipeline that crosses the property.

“The directed biogas will them be transported to one of Duke Energy’s combined cycle power plants. The combustion of swine derived from directed biogas will generate renewable energy credits (RECs) in order to meet North Carolina’s renewable energy portfolio standards (REPS) compliance obligations,” says Payne.

Under North Carolina's REPS, Duke Energy companies must meet specific compliance targets for swine and poultry waste.

According to Payne, the digester will be designed, built and operated by Cavanaugh.

“Cavanaugh has been operating the exact digester design with swine waste in the state successfully for four years. Guild Associates, who currently has provided over 60 units for similar gas cleaning projects throughout the world, including operating projects in North Carolina, will provide the gas upgrading system,” he says. “Duke Energy is working diligently with Piedmont Natural Gas to set up transportation agreements and develop proper tracking methods for the directed biogas to be moved to its combined cycle plants for combustion.”

The project should be operational by the summer of 2017.

“The project has an expected maximum production potential of about 80,000 MMBtu’s/year of renewable natural gas or 11,100 MWHs/year,” says Payne. “The gas will be produced from wastes generated from roughly 60,000 feeders to finish pigs located on five contiguous farms, owned by three entities with a long and successful operating history. The farms have provided the project with 15-year feedstock agreements along with all required access and easement rights.”