This Waste-to-Energy demonstration is the first-of-its-kind which was constructed through the support of Duke Energy, Duke University, and internet giant Google. Funding for the project was also provided by the NC Division of Soil and Water Conservation and the USDA Natural Resource Conservation Service. Loyd Bryant who is a forward-thinking farmer allowed this project on his 9,000 head swine farm in Yakinville, N.C., called Loyd Ray Farms.
The renewable energy system works in this manner. The waste generated by the pigs is directed into an anaerobic digester, where bacteria consume the waste and respire biogas that is rich in methane. This methane is then used as fuel for a 65 kilowatt microturbine electricity generator. The electricity that is generated is used to power a waste treatment system to clean up the wastes that are not converted to biogas, and power about half of the farm.
“By generating electricity from the waste, we are able to power systems to reduce the odors and emissions from the farm, and treat the wastes to a higher degree than before,”said Gus Simmons, PE and lead designer for the project. “Not only are we able to treat the waste without adding cost to the farm owner, the revenues generated by the project repay the capital cost for construction.” Additionally, the waste stream is recycled and the energy in the animal feed is re-harnessed, thereby saving the consequences of runoff into the streams.
This ‘next generation’ project does more than just generate electricity; the system, which was designed by Cavanaugh to meet the environmental performance standards for new and expanding hog farms set forth by North Carolina law, has dramatically reduced the odors on the farm. Marvin Cavanaugh, who is responsible for the day-to-day operations of the project, reported that the neighbors realized a huge difference. The system also reduces greenhouse gas emissions through the combustion of the methane in the generator. Methane is 21-times more potent than carbon dioxide, as a greenhouse gas. The reduction in emissions from this project is the equivalent of taking 900 cars off the road.
In return for their funding support, Duke Energy receives the RECs that are produced to offset the requirements of the NC Renewable Energy Portfolio Standard, which requires utilities, like Duke, to generate a portion of its electricity from pig waste. Similarly, Duke University and Google receive the Carbon Credits that are generated to aid in their goals of reducing their carbon footprint at their North Carolina facilities. “Through this pilot, (we are) showing how these projects can make economic sense for North Carolinians and lead to dramatic reductions in emissions over the long term,” wrote Jolanka Nickerson, the program manager for Google’s Carbon Offsets Team. “We hope technologies like this can scale across the U.S. and world. This pilot project is performing better than even we expected.”
Cavanaugh & Associates, P.A. is a progressive civil/site consulting engineering firm that specializes in cutting-edge solutions in surveying, engineering, environmental and utility services. ACEC/NC is a professional association of over 210 member firms in North Carolina, composed of 8,000 professional engineers, technicians and scientists, and a member organization of the American Council of Engineering Companies in Washington, D.C. Projects that are winners at state level EEA competitions are eligible for ACEC’s National Engineering Excellence Award competition.