A $30.1 million project to use the methane-rich biogas produced by one of Columbus' South Side sewage treatment plants to fuel generators and produce electric power and heat was approved Monday by the Columbus City Council.
Within two years, the Jackson Pike plant will burn methane extracted from its series of large, domed "anaerobic digesters" that motorists pass along Interstate 71 south of Downtown as fuel for both turning electric generators and heating the plant using a new combined heat and power (CHP) engine system.
The project is part of the city's ongoing effort to produce electricity from wasted energy. The sewage treatment plant currently "flares," or burns off without any use, the methane produced by sewage — a process that is both dirtier for the environment and wastes potential heat energy.
"You're building a power plant inside an existing (and continuously operating) wastewater treatment plant, so obviously it's a very complicated process," Council member Rob Dorans, chair of the utilities committee, told The Dispatch after the meeting. "The way we're releasing (methane) right now is much dirtier. We don't have any use for it. We don't have any infrastructure for it."
The city hopes to break even on the project after an unspecified number of years by providing half of the waste treatment plant's electric power using two heat-recovery steam generators, which a 2018 study estimated at potentially up to 3 megawatts.
The digesters use some of the methane — the main component in natural gas — in the process of breaking down and treating sewage, but the rest is flared as a waste product, said the report by Arcadis, an engineering firm hired by the city.
A 2011 U.S. EPA study found that biogas cogeneration through CHP systems was "technically feasible" at more than 1,300 wastewater-sewage treatment plants across the U.S., and could be "economically attractive" at up to about half of those sites. "CHP can save facilities considerable money on their energy bills due to its high efficiency, and it can provide a hedge against unstable energy costs," the report found.
The Dispatch reported in January that the city was breathing new life into its utilities' generation program by approving $15.3 million in bond money to repair the electric hydrogenerators at O'Shaughnessy Dam. The dam, located near the Columbus Zoo and constructed in the 1920s, began producing power in 1987 under a federal program to reduce reliance on foreign oil. It had a 5-megawatt capacity — enough to potentially power thousands of homes. That facility should be operational once again by mid-2023.
In other business Monday, the council: