Swine Waste-to-Energy (Loyd Ray Farms)

Loyd Ray Farms


Loyd Ray Farms (LRF) is an 8,600-head feeder-to-finish swine operation located in Yadkinville, North Carolina. Traditional waste management systems on swine farms store waste in open-air lagoons that release methane, a greenhouse gas 25 times stronger than carbon dioxide, into the atmosphere. To reduce these greenhouse gas emissions, produce renewable energy, generate carbon offsets, reduce odor, and minimize the overall environmental impact of the swine farm, an innovative waste management system was installed at the farm.

The project was made possible through the collaborative efforts of Duke University, Google Inc., and Duke Energy, and grants received from the Natural Resources Conservation Service's (NRCS) Environmental Quality Incentives Program (EQIP) and the NC Division of Soil and Water Conservation's Lagoon Conversion Program. The system generates carbon offsets for Duke University, while all renewable energy credits (RECs) generated by the project are contracted to Duke Energy for their project partnership. The electricity generated is either used onsite by the swine-farm facilities, the innovative system, or is fed back into the grid.

Project Highlights:

  • Has the capacity to produce approximately 2,500 offsets annually
  • Project registered with Climate Action Reserve
  • Can generate approximately 300 Renewable Energy Credits (RECs) annually
  • System is cost competitive when compared to other systems that clean up swine waste ($460 per 1,000 lbs of steady-state live weight)

How the system works

The hog waste from 8,600 hogs is flushed into an in-ground lined and covered anaerobic digester that produces and captures biogas. The biogas is used to power a 65-kilowatt microturbine with excess beyond this capacity diverting to the system's flare, during times of high biogas production. From the digester, the liquid waste flows to an open-air basin where the wastewater is aerated to reduce the concentrations of ammonia and other remaining pollutants so that it can be reused to flush the barns maintaining healthy populations of good microbial communities.

Photo of how Loyd Ray Farms works

Project Co-Benefits

Educational: Provides faculty and students with research and touring opportunities through the Pratt School of Engineering, Nicholas Institute for Environmental Policy Solutions and other partners.

Social: Reduces odor and soil toxicity, potentially increasing surrounding property values.

Environmental: Reduces ammonia and BOD levels and increases soil and groundwater quality. Lowers the likelihood of waste run-off that causes fish kills.

Scalable: Serves as a model for livestock waste management through our peer reviewed publications and best practice guidance materials to support a growing industry.

Project Partners: Duke Pratt School of Engineering, Nicholas Institute for Environmental Policy Solutions, Google, Duke Energy, Cavanaugh & Associates, NC Soil and Water Conservation, and Natural Resource Conservation Services.

photos of students at Loyd Ray Farms
Three of Sustainable Duke's summer interns and Rebecca Hoeffler, visited the farm in the summer of 2017.


U.S. Livestock Offset Project Protocol (CAR)

Bass Connections - Framework for Solving Animal Waste Issues (whitepaper)

Peer-Reviewed Publications

Performance evaluation of a full-scale innovative swine waste-to-energy system (2016)

Design and Assessment of an Innovative Swine Waste to Renewable Energy System (2016)

Nitrification of anaerobic digester effluent for nitrogen management at swine farms (2014)

A spatial-economic optimization study of swine-waste derived biogas infrastructure design in NC (2013)