Duke Energy Corp. said Monday it is expanding its renewable energy from livestock waste, adding poop power to investments the country’s largest electric company has made in whirring wind turbines and acres of solar arrays.

The North Carolina utility said it contracted with Boulder-based Carbon Cycle Energy to build plant that collects methane from pig and chicken waste and refines and delivers enough gas to generate enough electricity to power about 10,000 homes a year.

“We’re collecting something that goes to waste; we’re putting it to good use and at the same time reducing smell, reducing negative environmental impact,” Carbon Cycle Energy co-founder Thomas Mulholland said.

The project is one of the largest in a growing number of waste-to-fuel efforts

spurred by a 2007 state law that requires electric utilities to get 12.5 percent of their power from renewable energy and energy efficiency by 2021. More than half the states have similar requirements. But North Carolina, the country’s second-largest pork producing state, with about 8.8 million hogs, is one of the few that requires utilities to produce some power from swine and poultry waste.