City to Implement Waste-to-Energy System Using Thermal OxidationPHG Energy, LaVergne, Tenn., inked an agreement construct a waste-to-energy system using PHG’s downdraft biomass gasification equipment for the city of Covington, Tenn. The environmentally friendly system converts waste materials or renewable biomass to a low-emission substitute for natural gas or other fossil fuels.

The PHG system will integrate established commercial technologies into a single system that simultaneously eliminates waste and produces heat that will be used for feedstock drying and the production of electricity. Covington Mayor David Gordon expects the waste-to-energy system to reduce the landfill and transportation fees for the 360 total tons of previously landfill-bound waste material the West Tennessee city produces each month.

PHG’s biomass gasification waste-to-energy system will be built adjacent to the wastewater treatment plant on city owned property. The waste to be used — approximately 12 tons per day — is primarily composed of woody biomass from the city’s collections. The use of biosolids from the treatment plant also is being investigated as a possible fuel for the gasifiers.

PHG’s technology combines a downdraft gasification system with thermal oxidation equipment and a 125 kW organic rankine cycle (ORC) power generator, manufactured by General Electric, to produce electric power. ORC generators offer low operating and maintenance costs while running without the need for constant attendance by an operator. Combustion of producer gas within the thermal oxidizer provides heat to power the system while maintaining emission levels comparable to the use of natural gas.

"Working with PHG is a win-win for Covington. It helps our environment and it helps our city financially," says said Mayor Gordon. “We looked closely at a PHG gasification facility in a nearby city, and thoroughly vetted the company before entering into this agreement. This system is a terrific financial solution to transportation costs and tipping fees we’ve been paying to get rid of waste, and keeps thousands of tons of material out of landfills each year.”

Covington, a city of 9,000 in western Tennessee, was awarded a $250,000 Clean Tennessee Energy Grant from Tennessee Gov. Bill Haslam and Department of Environment and Conservation Commissioner Bob Martineau for the waste-to-energy system. Total cost of the project is $2.25 million, with $2 million of funding obtained through the Tennessee Municipal Bond fund in the form of a general obligation bond issue.

Construction began in November and will take several months to complete. PHG Energy’s gasification systems provide a non-burning thermo-chemical process in which waste materials or renewable biomass is economically converted to a fuel gas with combustion properties similar to natural gas. That fuel can be utilized for thermal applications such as kilns or boilers or used to produce electricity through either reciprocating engine or other types of generators.