GET MORE INFORMATION
• EPA's Landfill Methane Outreach Program
• Solid Waste Association of North America
James Flowers can't just call Jiffy Lube when it's time to do maintenance to the new engine at work.
The oil change, required every two months, takes four 55-gallon drums of industrial lubricant, and a set of spark plugs runs about $6,000 for the V-12 engine.
The motor is at the heart of a new methane gas-to-electricity system at the sealed-off Catoosa County landfill, which Flowers manages.
But Flowers isn't complaining.
"It hums along pretty good," he said.
Catoosa officials say they're pleased with the new $2 million system, which is meant to pull a $7 million monkey off the county's back. That's the estimated cost to monitor and maintain the defunct 60-acre landfill at the end of Shope Ridge Road until 2035 as required by the state.
The landfill opened in 1974 and stopped accepting trash in 2005. Yet it still emits methane given off by rotting organic matter. Another environmental concern is liquid runoff from the landfill, technically known as leachate.
"We have to monitor it for at least 30 years after it closed," Flowers said.
To keep an eye on the landfill, Catoosa County must pay to monitor for groundwater contamination and greenhouse gas emissions as well as employ three full-time workers to mow the landfill and otherwise maintain it.
"You'll end up spending $280,000 a year maintaining that site," Catoosa County Chief Financial Officer Carl Henson said. "We had to come up with some source of revenue to relieve the general fund of that liability."
Until recently, landfill gas was just going up in smoke. To get rid of methane, the county was burning it in a flare on site.
But thanks to a Tennessee Valley Authority program that made electricity generation economically feasible, Catoosa County now earns $50,000 a month selling methane-generated electricity into the power grid, part of TVA's Generation Partners pilot program.
"That made the project feasible," Henson said.
The landfill should produce enough methane to keep the V-12 engine humming for 16 years, and proceeds from TVA should fund the landfill's final closure without burdening taxpayers or straining the county's general fund, he said.
"We're hoping to cover that $280,000 [annual cost] plus pay back the $2 million cost of this project," Henson said.
BIG ENGINE IN A BOX
Boiled down to essentials, the methane-to-electricity system is easy to understand.
Picture an engine, like one you'd find inside a car or truck. Now supersize it and house it inside a shipping container. Then place a giant muffler, exhaust pipe and radiator on the container's roof.
In a nutshell, that describes the "containerized" 12-cylinder power plant the county bought from GE Jenbacher, an Austrian manufacturer of specialty generators that run on waste gases emitted by landfills, sewage treatment plants, coal mines and the like.
The power plant was shipped from Europe to Savannah, Ga., then hauled to Catoosa. Many of its gauges are in German, and the engine block is painted green, presumably as a nod to the "green" electricity the plant generates.
When the big V-12 runs, it spins a generator that sends electricity into the power grid, producing enough kilowatts to power about 200 homes.
The methane gas that feeds the V-12 comes from 88 extraction wells that pierce the landfill's grassy hide. A suction pump system helps draw out the methane.
LANDFILL GAS USE NEW TO SOUTH
It may sound obvious to use methane gas to produce electricity instead of "flaring" it off as smoke and flame. Yet Georgia only has 15 landfill gas energy projects, Tennessee has nine, Alabama has three, and Mississippi just got its first landfill gas project, according to the U.S. Environmental Protection Agency's Landfill Methane Outreach Program.
Nationwide, there are 576 operational landfill gas-to-energy projects and 510 landfills that are good candidates for the system, according to the EPA program, which offers technical assistance and other help to communities considering such the project.
The Northeast and the West have more gas-to-electricity projects than the Midwest and South, said Bill Malone, assistant director of sanitation in DeKalb County, Ga., which opened its landfill gas-to-electricity plant in 2006 and was the first one to sell electricity to Georgia Power.
"One reason the South and the Midwest have been low is we have such low electrical rates," Malone said.
DeKalb's gas-to-electricity project was a success; it's already paid for, Malone said. Georgia Power, which serves all but four of Georgia's 159 counties, is paying DeKalb a "little bit more" for electricity, Malone said, and that's what made the plant feasible.
Now, the county is working on a project to clean up methane to the point that it can be used to fuel garbage trucks. Other uses for methane around the country include firing brick kilns and heating greenhouses.
Catoosa County officials had a lot to figure out before they bought their methane-to-electricity system.
For one, they needed to know how much methane the landfill produced.
"It was 2010 before we had an actual measurement," Henson said.
The county also had to buy an engine that was the right size to optimize electricity production - and revenue. Plenty of firms were willing to sell Catoosa a bigger engine than it needed, County Manager Mike Helton said.
One strategy that county officials employed was buying two sets of $6,000 spark plugs to minimize downtime. The plugs are reusable; they just need to be cleaned with a wirebrush between uses. Having a clean set ready to go reduces downtime when the plugs need changing every three weeks.
County Commissioner Bobby Winters said credit for the gas-to-electricity project should go to the county's five-member Public Works Committee, which Winters sat on until it was dissolved in 2009.
"I just think the Public Works should get some credit for the work we did," said Winters.
He said he visited gas-to-electricity plants in cities such as La Grange, Ga., to get ideas about what Catoosa might do.
Other lessons Catoosa officials learned could help other counties make their landfills less of a liability. For example, to help insure a steady methane supply, Catoosa installed a well-dewatering system which automatically pumps leachate out of the landfill into the sewer system for treatment miles away at Chattanooga's water treatment plant at Moccasin Bend on the Tennessee River.
"You must take the water out of the well in order to extract the gas; otherwise, it's vapor-locked," Henson explained.
Previously, county workers dewatered the landfill by pumping out the wells one at a time, which Henson said was "very time-consuming and labor-intensive."
A side benefit of dewatering the landfill is that it reduces the chance of groundwater contamination, officials said, which has been a problem at landfills elsewhere such as in Rhea County, Tenn.
Catoosa officials said they plan to hold an open house soon so the public can view the methane-to-energy facility. Other municipalities also are welcome to see how Catoosa's is using its landfill gas to generate power.
"They're welcome to come look at it. We're proud of what we've done," Helton said.