Editor's Note: A story Thursday about a new gas collection system at the Johnston County Landfill incorrectly stated that the system produces 1.6 megawatts of electricity a year. The system produces 1.6 megawatts of electricity when working at capacity.
SMITHFIELD -- Johnston County is now using trash to power 1,500 homes, a move county officials say helps both the environment and the countys pocketbook.
About 30 people gathered Wednesday at the Johnston County Landfill for a ribbon-cutting ceremony and tours of a new facility that collects gas from the landfill. The gas is then turned into electricity using a generator and sold to Duke Energy Progress.
The facility began running last month and produces up to 1.6 megawatts of electricity when working at capacity.
As trash decomposes, it produces gasses such as methane and carbon dioxide that contribute to climate change. According to the U.S. Environmental Protection Agency, methane gas is the second most common kind of greenhouse gas released by human activities in the country, and 17 percent of it comes from landfills. Methane has a much greater environmental impact than carbon dioxide.
In 2010, Johnston County contracted the company C2i Methane, based in New York, to use its own money, not county funds, to build the facility. C2i Methane owns the facility and has a 20-year agreement with the county for gas collection. The revenue from selling the electricity will be shared by the company and the county.
Officials with the county have wanted to create this type of project since the early 1990s, but at the time there wasnt enough money to make the project happen, said Rick Proctor, solid waste division manager for the county.
In 2007, North Carolina established a Renewable Energy and Energy Efficiency Portfolio Standard, which requires 12.5 percent of the electricity a public utility company sells in North Carolina to be produced with renewable sources by 2021. That has caused power companies to become more interested in buying the electricity produced through landfill gas, making the effort profitable, Proctor said.
Thats what the developers really liked, and we had the door open for it, Proctor said.
C2i Methane partnered with local groups, including Caterpillar and SCS Engineers in Charlotte, to build the facility.
Pipes were placed into the landfills trash heaps to capture the gas, said Matt Wells of C2i Methane, who gave tours of the facility. The gas is then heated and cooled to remove moisture.
The methane is then pumped into a huge Caterpillar 3520 engine, large enough to be enclosed by a small trailer and burning hot to the touch. The generator turns the methane into electricity, which is then added into the power grid through lines provided by Duke Energy Progress.
The rest of the gas, mostly carbon dioxide, is flared off during the process into the atmosphere.
As of now, the system produces 1.6 megawatts of electricity each year, said Annika Colston, president of C2i Methane. But Colston hopes to increase that amount to either 2.4 or 3.2 megawatts.
As they bring in more waste, we can increase the capacity of the project, she said.
Even after a landfill closes, the trash still produces gas, so the methane could continue to be collected for years to come, she said.
Johnston County is only the latest landfill to use methane as fuel for factories or to generate electricity. According to the EPA, at least 30 other landfills in North Carolina use methane gas to generate power, including the closed North Wake Landfill in Raleigh. In December, a Richmond, Va., company agreed to pay Wake $17.7 million over 15 years to extract methane gas from the South Wake Landfill.