Hog waste producing electricity, carbon offsets
The system, on a hog finishing facility 25 miles west of Winston-Salem, converts hog waste into electricity and creates carbon offset credits
Yadkinville, N.C., September 12, 2011 — A pilot waste-to-energy system constructed by Duke University and Duke Energy garnered the endorsement of Google Inc., which invests in high-quality carbon offsets from across the nation to fulfill its own carbon neutrality goals.
The system, on a hog finishing facility 25 miles west of Winston-Salem, converts hog waste into electricity and creates carbon offset credits. By capturing greenhouse gases from hog waste and burning them to run a turbine, the system produces enough electricity to power 35 homes for a year.
It is expected to be able to prevent the release of greenhouse gases equivalent to nearly 5,000 metric tons of carbon dioxide per year, which is like taking 900 cars off the road. The $1.2 million prototype system was built at Loyd Ray Farms, a 9,000-head hog finishing operation northwest of Yadkinville, N.C.
It is intended to serve as a model for other hog farms seeking to manage waste, reduce greenhouse gas emissions, and develop on-farm renewable power.
Though this is an established farm, the system meets North Carolinas environmental standards for new and expanded hog farms. It was built mostly with off-the-shelf technology and is an open source design that others may freely adopt.
The system includes a lined and covered anaerobic digester and a lined aeration basin. Methane gas is collected under a thick plastic dome over the digester. Gas not burned in the turbine is burned in a flare to prevent its release.
Open waste lagoons currently in use on most North Carolina hog finishing farms are prolific producers of methane gas, which is 21 times more potent than carbon dioxide, pound-for-pound, as a greenhouse gas.
Duke Energy and the university will share operational and maintenance costs for the first 10 years of operation. Google will assume a share of the university's portion of the costs in return for a portion of the carbon offsets for a 5-year term.
The project is expected to yield many benefits beyond renewable energy production and greenhouse gas reductions, including improved water and air quality; reduced odors, pathogens and nutrients; and increased farm productivity.
As North Carolina continues to explore new ways to generate renewable energy from hog waste, this site serves as a showcase for what others can do to capture the energy from hog waste and turn it into usable electricity for customers.
Capturing the methane creates carbon offset credits for Duke University and Google and using it to generate electricity creates renewable energy credits for Duke Energy. Loyd Ray Farms will use surplus electricity on-site.