A newly completed renewable energy project in North Carolina is now producing pipeline quality biogas from hog farms — and using that to generate electricity for Duke Energy customers.
Duke Energy and Raleigh-based swine waste-to-energy project developer OptimaBio first finalized the project in May 2016. Called Optima KV, the project in Duplin County, North Carolina, captures methane gas from five local farms’ hog waste, Duke Energy explained. Then, more than 42,000 feet of in-ground piping move the methane to a central location, where the gas is cleaned and converted to pipeline-quality natural gas.
“The project injects the renewable natural gas into the Piedmont Natural Gas system, which transports it to Duke Energy’s Smith Energy Complex in Richmond County, where it is used to produce electricity,” the utility says. The project’s interconnection to Piedmont Natural Gas was completed last week.
Under a 15-year term, Optima KV is expected to produce about 80,000 MMBtus of pipeline-quality captured methane annually, which should yield about 11,000 megawatt-hours of electricity each year, Duke Energy says.
Under North Carolina’s Renewable Energy and Energy Efficiency Portfolio Standard law (REPS), established in August 2007, all investor-owned utilities in the state must supply 12.5% of 2020 retail electricity sales from eligible energy resources by 2021.
The law’s overall target for renewable energy includes technology-specific targets of 0.2% energy recovery from swine waste. Duke Energy says the new project will help it satisfy the state’s swine-to-waste energy mandate. Headquartered in Charlotte, North Carolina, Duke Energy’s Gas Utilities and Infrastructure business unit distributes natural gas to around 1.6 million customers in the Carolinas, Ohio, Kentucky, and Tennessee.
“Historically, renewable natural gas has been used by smaller, on-site generators that are connected to the overall energy grid,” Duke Energy says. The utility added that its larger, more efficient plants allow for more renewable energy to be created with the same amount of renewable natural gas.
Swine waste-to-energy has taken off in other areas as well. Last October, the world’s largest pork processor and hog producer Smithfield Foods launched an initiative called Smithfield Renewables. Projects under the initiative include converting manure from hog farms into energy, which the company anticipates will help produce over 2 billion cubic feet of renewable natural gas.
“Because we operate a lot of hog farms, we have a lot of manure,” William Gill, vice president of environmental affairs at Smithfield Foods, said at the 2017 Environmental Leader Conference and Energy Management Summit. “We’ve partnered with tech providers and utility experts, and we have a manure farm in Utah that actually creates electricity from manure.”
One of the challenges with waste-to-energy systems has been the cost of adding infrastructure to farms in the United States. Nevertheless, projects have proliferated, driven by renewable energy requirements and corporate GHG reduction targets.
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