Power of Hog Poop

The 71-year-old farmer and his brother co-own Butler Farms in Harnett County, North Carolina. The 108-acre commercial hog farm won the North Carolina Clean Energy Business Innovation Award by the North Carolina Sustainable Energy Association in 2013.

Butler’s journey toward renewable energy began out of concern for his community -- in particular, for his neighbors.

“The odor doesn’t bother us very much but, we make a living off of pig farming… my neighbors don’t,” he said. “They have to smell the same thing I smell and they don't get any money out of it.”

The “odor” is that of the high volume of manure that Butler’s hogs produce. The farm houses between 7,000 and 8,000 pigs at a time and all of their waste is poured into giant ponds called “lagoons.”

Back in the 1990s, the farm switched from a smaller, more traditional agricultural endeavor to raising commercial hogs for Prestage Farms, a large turkey and pork producer. The hog farming industry has grown exponentially across the country, increasing in value 25 percent in value between 2007 and 2012, according to the U.S. Department of Agriculture.

North Carolina is the second largest pork producer in the United States, and the county where Butler Farms is located borders the two largest hog counties in the country, Duplin and Sampson.

The same USDA report declared that only three states, including North Carolina, were responsible for over 50 percent of the industry’s sales and inventory.

The $22.5 billion industry is composed of independent farmers and large corporations like Prestage, Smithfield and Maxwell Foods. Under this set up, Butler does not own the hogs, but he owns everything else: the land, the hog pens, the silos, the grains and the hog poop.

When he became a hog farmer, his neighbors expressed their concern. While searching for ways to reduce the smell of the “poop pits”, he found lagoon covers -- tarps that could help contain the smell.

Butler didn’t realize, however, that the covers also trap the naturally occurring methane biogas the poop produces. That realization spawned Butler’s renewable lifestyle. Methane, a powerful greenhouse gas, damages the environment when released into the atmosphere. It is more than 20 times more potent and has a higher global warming potential than carbon dioxide. At that point, Butler didn’t realize how much methane his farm was producing.

The covers help trap the methane in the ponds, enabling Butler to use the methane biogas as generator fuel by turning it into carbon dioxide. His 180 kilowatt generator then turns the carbon dioxide into energy to power Butler Farms. After three months he has enough energy to power Butler Farms the rest of the year and, during the other other nine months, the farm has a “power purchase agreement” with the South River Electric Membership Cooperative.

This power purchase agreement allows Butler to sell the surplus energy that he is generating to SREMC and generate revenue. The energy is then rerouted to local homes for electricity and other uses.

“I think renewable energy production has become one of the few activities that is bring economic resources to rural communities around the state and country,” said Greg Gangi, an environment and ecology professor at the University of North Carolina at Chapel Hill.

He also said that environmentally friendly practices are “expanding opportunities for farmers by allowing them to also become energy producers.”

Hog farming, and the mass production of livestock in the agricultural sector contributes about one third of all methane emissions in the ozone through feces.