Pork power: Renewable energy source?

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Electric power holding company Duke Energy is to purchase swine and poultry waste from a planned facility in North Carolina and use the methane produced to generate renewable electricity at four power stations.

"It is encouraging to see the technological advances that allow waste-to-energy projects in North Carolina to be done in an environmentally responsible and cost-effective manner for our customers," David Fountain, North Carolina president of Duke Energy, said in a statement this week.

"The gas from this project will generate carbon neutral electricity compared to the emissions that would result if the waste was left to decay naturally," Fountain went on to add.

The facility will be built and owned by Carbon Cycle Energy.

According to Duke Energy, the methane, once captured, will be treated, injected into the pipeline system, and then used at four Duke Energy plants. Around 125,000 megawatt hours of renewable energy should be produced every year, "enough to power about 10,000 homes for a year."

The potential of producing energy from food and drink sources is considerable, and not confined to pigs and chickens.

Last year, Sustainable Energy spoke to Arthur Kay, founder and CEO of bio-bean, a company that turns waste coffee grounds into biomass pellets and briquettes.

"It's essentially using a product which is already in the carbon cycle and used for a primary purpose," Kay told CNBC.

"In this case it's coffee but other examples would be, for instance, used cooking oil," he added. "Essentially, what we've done is… identified a new second generation fuel that hasn't been valorized before."