Jerry Stewart

Materials are rotting at the old Summit landfill near Collegedale, but it’s not all going to waste.

Since September 2005, the city has contracted with Cogeneration Technologies, Inc., which uses two engines to convert methane gas from the landfill into electricity that the company sells to the Tennessee Valley Authority.

“It’s a shame if you collect (methane) and burn it when you can make energy with it,” said Cogeneration Technologies President Mike McCullough, who has a revenue-sharing arrangement with the city of Chattanooga.

“It’s a gas that would normally not be used for anything,” said Jerry Stewart, Chattanooga’s waste resources director. “It’s a resource there based on decomposition of municipal waste.”

As the city eyes more green-friendly initiatives, Mr. Stewart said he hopes to put together a feasibility study to determine how methane could be used to make energy at the City Landfill on Birchwood Pike and at the Moccasin Bend Wastewater Treatment Plant.

At the Summit landfill, which closed in March 1999, about 50 wells now collect methane and vacuums pull the gas down to a flare, which burns off the methane.

Some of the gas, however, goes to Mr. McCullough’s operation. He said he can produce about two megawatts of electricity continuously, enough to power roughly 150 to 200 homes for an hour.

Dr. Randy Gentry, director of the University of Tennessee’s Institute for a Secure and Sustainable Environment, said while he said he is not sure how many municipalities in the Volunteer State are using methane to create electricity, there is a national push toward the technology.

“More and more landfills are heading in this direction,” said Dr. Gentry, an associate professor of civil and environmental engineering.

Instead of methane being “wasted waste,” he said, it can be put to good use.

“In this way it’s actually preferable to use it as a product,” Dr. Gentry said.

Councilwoman Sally Robinson, who sits on the city’s green committee, which is looking at ways to reduce the city’s carbon footprint, praised city personnel for being “innovative” in trying to harness an existing resource.

“It’s kind of like in the early days when we were taming rivers and using the current of the river to convert it into energy,” she said. “I think that these things are wonderful innovations.”