Last week, Covington, Tennessee, mayor David Gordon flipped the switch on a new gasification power plant that puts his town squarely on the map of cutting-edge sustainable practices — by turning wood waste and sewage sludge into energy.
Town leaders, PHG Energy officials, and the media were on hand for the plant’s grand opening on October 30th. The morning-long event included speeches, a barbecue plate lunch, and a tour of the facility, located just steps away from the town’s sewage treatment plant.
Calling himself a “confirmed nerd,” Gordon says he spent two years researching energy conversion before enlisting PHG Energy’s assistance in building the plant. Many cities have expressed interest in this emerging technology, but no one wanted to be first. “It’s not just a feel-good,” Gordon said. “I’m a steward of taxpayers’ money. What we did had to make financial sense, not just be good for the environment. I was finally convinced that this would make financial sense.”
“Yesterday, Covington was throwing wood waste and sewage sludge into the landfill,” said Chris Koczaja, PHG Energy vice president of sales and engineering. “Today, they’re mixing 80 to 90 percent woodchips with 10 to 20 percent sewage sludge and gasifying it into heat energy.”
What helped was a $250,000 grant the town received from the Clean Tennessee Energy Grant Program, administered by Tennessee’s Department of Environment and Conservation. The funds, which were part of a five-year federal settlement from the Tennessee Valley Authority, are earmarked for energy projects that operate with lower emissions and pollutant rates in cities and towns across the state.
“We funded this to see if this will work, so we can have data,” said Kathy Glapa with the Office of Sustainable Practices. “The town will report for five years on their carbon reduction and energy savings.”
The $2.5 million gasification plant is designed to burn up to 12 tons of waste a day. It can even take tires. Small towns such as Covington (pop. 9,500), a rural community 40 miles north of Memphis, spend thousands of dollars annually to haul tons of wood debris to landfills, paying approximately $30 per ton in transportation and tipping costs.
Now, the plant’s construction tab will be offset with $3.5 million in savings over 20 years. PHG Energy officials say they are pleased with the results, since it is the first time the Knoxville-based company has built a downdraft gasifier using these two different waste streams. The biggest challenge, according to PHG Energy president Tom Stanzione, was navigating the state’s regulatory requirements. But the savings, he notes, aren’t just monetary. “You’re saving in CO2 emissions. This plant represents significant carbon reduction,” he said.
Little remains at the end of the process but “biochar,” a carbon-rich charcoal. Several companies have expressed interest in using this end product to produce fertilizer, something Gordon’s office plans to investigate. The plant doesn’t require specialized personnel to run it; instead, employees at the sewage treatment plant are being trained to take the helm.
Gasification is not a new technology. Developed during the 19th century, it was first used to burn coal, producing gas for street lamps. But as fossil fuel emerged, the development of gasification slowed. Now, it is on the upswing again, as companies like PHG Energy scale down the size of the plants and find different waste streams that can convert biomass into energy.
“This is cutting-edge,” said Josh McGill, with Applied Chemical Technologies (ACT), the company that worked with PHG. “Lots of people are talking about it, but not many are doing it.”
“This technology is real, and it’s cost-effective,” added ACT founder, Ray Shirley. “A lot of people will be coming to Covington to see how this works.”
