Before its upgrade, Loyd Ray Farms was a classic “feeder-to-finish” operation, bulking up thousands of swine for slaughter every year. These large, confined hog facilities spread rapidly through North Carolina in the 1980s and 1990s. But during this heyday, heavy rains caused several manure lagoons in the state to rupture; public outrage swept the country as pathogen-laden sludge leached into waterways.
Meanwhile, researchers were showing that besides soil and water contamination, hog CAFOs emit high volumes of the potent greenhouse gas methane (pound for pound, hog manure produces twice the methane of cattle manure) and ammonia, which has been linked to respiratory ailments. Farmers exacerbate these health hazards when they spray the liquid manure onto their fields as fertilizer, volatizing more chemicals and producing an ungodly stench.
Seeking to redeem its hog industry, the Tar Heel State imposed a temporary ban on new or expanded hog farms in 1997. A decade later, the state signed the ban into law but exempted farms that met strict environmental criteria, such as eliminating the discharge of animal waste to groundwater and preventing the release of pathogens to the environment.
In 2007, with this new environmental law in place and the renewable energy law under consideration in the state Legislature, environmental scientists at Duke University seized the opportunity to reimagine swine farms. They teamed up with Duke Energy, North Carolina’s largest utility, to convert a standard hog CAFO into a sustainable farm. Engineers from Cavanaugh Solutions designed a system that would turn the animal waste into energy. Soon, Google got wind of the project. With its well-known corporate commitment to reduce the carbon footprint of its operations to zero, Google’s top brass saw investment in the project near its Lenoir, N.C., data center as a step toward achieving that goal. All the group needed was a factory farm to test the technology.
When a project manager approached Loyd Bryant with the blueprints in 2009, the owner of Loyd Ray Farms was up for experimenting. “I liked the idea of reducing odors on the farm, which I knew my neighbors would appreciate. I liked the idea of having healthier pigs from the ammonia control, which helps them grow better and reduces mortality. And I liked the idea that I might be able to expand my farm someday because of this innovative system,” Bryant explains.
A Day on the Farm
Now Bryant’s daily chores include flushing 80,000 gallons of manure from two barns into the farm’s biodigester, a 174-by-218-foot plastic-covered pit. Inside, anaerobic bacteria — which do not require oxygen — silently convert the organic matter into methane, carbon dioxide and other chemical byproducts. Bryant’s biodigester mixes the liquid inside to keep digesting bacteria in constant contact with the waste material. This maximizes digesting efficiency and helps the bacteria outcompete pathogenic strains, reducing pathogen loads without the use of synthetic chemicals.
At the other end of the digester, Bryant captures biogas composed of about 60 percent methane and 40 percent carbon dioxide. A machine called a gas skid brings this mixture to the right temperature and pressure for turning a 65-kilowatt microturbine. The electricity it generates is enough to run the waste treatment system plus the lights and machinery in five of Bryant’s nine hog barns. Any excess biogas is burned in a flare that converts methane into less-polluting carbon dioxide.