In a secluded corner of rural eastern North Carolina, at the end of a long and winding farm lane, a pit of stinking hog manure is doing its bit to save the world from climate change.
It may be a whiff of things to come.
"You're standing in the middle of about 12,000 head" of hogs, says Kraig Westerbeek, an executive at Smithfield Foods, the country's biggest pork producer. The animals live in rows of buildings nearby, eating and excreting. Their manure flows into a big pond, called a lagoon, right in front of us. This is the standard form of treatment for hog waste in this part of the country. In the lagoon, bacteria go to work on the manure, breaking it down.
"The bacterial action releases a biogas that's 60% to 65% methane," Westerbeek says.
On most farms, that gas just goes floating off into the air — and contributes to the overheating of the planet. Methane is a greenhouse gas with a warming impact at least 25 times greater, per pound, than carbon dioxide.