Dayton’s wastewater treatment plant produces millions of cubic feet of biogas each year that officials say is burned and wasted. But the city now aims to find a company to buy that byproduct and convert it into renewable natural gas.
“The main benefit of this project is the repurposing of the valuable biogas generated at the Water Reclamation Facility to a revenue generating process,” said Chris Clark, Dayton’s water reclamation division manager. “Equally important is that we play a role in the city’s sustainability initiatives by reducing our overall carbon footprint of city facilities.”
This project is part of a larger city strategy to shift to 100% renewable energy sources by 2035.
The city earlier this year declared a climate emergency, and leaders last year approved a comprehensive sustainability strategy.
Dayton’s wastewater treatment process generates biogas — a mix of methane and carbon dioxide that is the gaseous product of the decomposition of organic matter.
Biogas can be turned into a valuable carbon-neutral renewable natural gas called biomethane when it is treated to remove impurities and moisture, said Michele Simmons, Dayton’s sustainability and environmental projects administrator.
Renewable natural gas is considered “pipeline quality” and can be used to fuel vehicles or replace traditional natural gas for heating and power.
Most renewable natural gas is used to fuel natural gas vehicles because of federal and state incentives, according to CenterPoint Energy, and the renewable natural gas supply has increased nearly 300% in the last five years.
But CenterPoint does not buy its natural gas supply for Ohio customers because of the state’s choice program, and that also means it does not have an opportunity to buy biogas for customers, a company spokesperson said.
Dayton’s wastewater treatment facility is one of the 1,300 facilities across the nation that use anaerobic digestion to produce biogas that is used on site, according to the U.S. Department of Energy.
Fewer than one in 10 U.S. wastewater treatment facilities produce and use biogas in this way.
Dayton’s water reclamation facility at 2800 Guthrie Road produced nearly 208 million cubic feet of biogas last year, most of which was used onsite to provide heat to city facilities and anaerobic digesters that break down waste, Simmons said.
About one-third of the biogas — 68.5 million cubic feet — was burned off in a process known as flaring, which converts waste gases into cleaner emissions, according to city documents.
City staff say this is a wasted opportunity.
Dayton last month issued a request for qualifications (RFQ) seeking companies that want to purchase and purify its biogas to sell on the natural gas market as a renewable product.
Dayton is looking for a company that will agree to clean the biogas at no cost to the city and install a pipeline to get the renewable natural gas into a supply network.
The city also expects to receive payment for the biogas it produces.
In addition to providing revenue to the city, the project will eliminate the need to “flare off” digester gas to the environment, reducing the city’s carbon emissions, Simmons said.
Biogas is more valuable than natural gas, Simmons said, and the city plans to use traditional natural gas instead of biogas to heat its wastewater facilities and anaerobic digesters if it determines this project will lead to sufficient new revenue to make it worthwhile.
The city typically spends about $4 million to $5 million each year on natural gas, city staff said, and last year it purchased more than 4.4 million cubic feet of natural gas from CenterPoint Energy.
Dayton is taking other steps to curb emissions.
The city is working on an internal study to identify operations and facilities that produce greenhouse gases, said Mark Charles, Dayton’s sustainability manager.
The city also has hired an outside group to study 18 municipal facilities to determine how to make them more energy-efficient, he said.
“The purpose for all of those things is to position ourselves should there be federal infrastructure money and climate change money coming down the road in two to three years,” he said.
President Joe Biden’s Build Back Better plan, which has cleared the House of Representatives, calls for large investments focused on combatting climate change.