Raleigh’s wastewater treatment plant now helps fuel city buses

RALEIGH

They may not know it, but whenever Raleigh water customers flush their toilets, they’re doing their part to help fuel the city’s bus fleet.

That’s because the city’s wastewater treatment plant now uses a process that captures natural gas from sewage, enough to keep up to 70 GoRaleigh gas-powered buses on the road.

The city has been working on the new system for six years and celebrated with a ribbon cutting on Wednesday.

“This project proves that we don’t have to choose between protecting our planet and operating efficiently,” Whit Wheeler, the city’s water director, said in a written statement. “We’re taking something that used to be waste and turning it into clean energy that will fuel our city for years to come.”

The city treats about 50 million gallons of wastewater a day at the Neuse River Resource Recovery Facility off Battle Bridge Road, about 10 miles southeast of downtown. The sprawling plant separates sewage into two main components: water clean enough to put in the Neuse River and a byproduct known as biosolids, which is used as fertilizer.

The part of the plant that treats solids and gets them ready to use as fertilizer was old and needed to be replaced. In 2019, the city began work on a relatively new technology called thermal hydrolysis, which heats the solids under pressure, like a pressure cooker. Combined with traditional anaerobic digestion, the process produces about half the biosolids as the old system, plus methane gas that can be cleaned and used as fuel.

The gas is fed into the distribution system for Enbridge, the region’s gas company, which then credits GoRaleigh against what it uses to fuel buses at its headquarters on Poole Road.

GoRaleigh received its first 17 buses that run on compressed natural gas in 2018. By January, 95 of its fleet of 122 buses will use CNG, according to spokeswoman Andrea Epstein.

The city began receiving credit for the renewable gas in June. By August, biogas from the plant was offsetting fuel demand for the majority of the GoRaleigh fleet, Epstein said.

Raleigh says it now has the first municipal wastewater plant to produce usable natural gas in North Carolina and that the city is one of only a handful nationwide to use gas derived from sewage to run their buses. In addition to Raleigh, the city’s utilities department treats sewage from Garner, Knightdale, Rolesville, Wake Forest, Wendell and Zebulon.

The city spent about $227 million on the new bioenergy recovery system. Any gas not needed by GoRaleigh can be sold, the city says. City officials say the project will help meet climate goals the City Council adopted in 2019 to reduce community-wide greenhouse gas emissions by 80% by 2050.