Ride On buses in Montgomery County will soon be powered by renewable energy produced by poop–another step the county is taking towards its climate goals. On June 21, the Washington Suburban Sanitary Commission (WSSC Water) announced a partnership with the county where they will sell methane gas captured at it’s forthcoming bioenergy facility, the Piscataway Bioenergy Facility.
“This agreement to turn methane gas into fuel for our buses is a win-win-win for our constituents, commuters and, most importantly, our environment,” County Executive Marc Elrich (D) said in a WSSC Water press release.
“Increasing the efficiency and reliability of our Ride-On bus system is critical toward the county’s goal of a 100% carbon emission reduction by 2035,” he said. “This agreement, along with our new electric buses and microgrids are important improvements within our fleet of Ride On vehicles.”
The Piscataway Bioenergy Facility in Accokeek is a renewable natural gas (RNG) energy production facility that captures methane gas from wastewater at WSSC Water’s Piscataway Water Resource Recovery Facility. Construction of the $271 million bioenergy facility began in 2019 and is expected to be complete by November 2024.
“Utilities are looking for any way to reduce costs and diversify revenues to take the pressure off customer rates,” said WSSC Water General Manager/CEO Kishia L. Powell in the release. “The Piscataway Bioenergy project will generate revenue and save our customers more than $3.4 million annually by reducing operating costs.”
On May 16, WSSC Water signed a five-year contract with the county to provide RNG for its Ride On bus fleet. The county plans to purchase approximately 500,000 dekatherms per year. A dekatherm is a unit of energy equivalent to one million British thermal units (Btu).
Michael Yambrach, chief of the Office of Energy and Sustainability at the county’s Department of General Services, told MoCo360 that the bioenergy project will be able to supply “between half and three quarters of the natural gas and compressed natural gas buses” in the county.
According to the press release, the bioenergy facility will “transform how WSSC Water handles biosolids,” which are the nutrient-rich organic material that are byproducts of wastewater treatment.
Transforming poop into energy begins with sewage. WSSC Water treats the sewage, or wastewater, from its service areas in Montgomery County and Prince George’s County at its Piscataway Water Resource Recovery Facility. Anything flushed down the toilet and drained into pipes head to the facility for treatment.
The facility heats up wastewater in a process called thermal hydrolysis, which breaks down the biosolids and kills pathogens. Afterwards the wastewater is transferred to an anaerobic biodigester for the “digestion” phase where the heat is reduced and allows microbes to digest the solids, stabilize the biosolids and reduce odors.
From these reactions in the biodigester, methane gas is produced and then upgraded to biomethane, or RNG. Upgrading is a process which removes any CO2 and other contaminants present in the gas. After biomethane is produced, a belt filter press squeezes out water from the biosolids to create soil amendment for gardens, forests, farms and lawns.
Biomethane gas that WSSC Water captures will be pumped into the Washington Gas system and then purchased by the county, Yambrach explained. The county will not buy the actual molecules of methane gas, but the energy equivalent of what WSSC Water will pump into the system.
The press release said WSSC Water received a license from the Maryland Public Service Commission to sell natural gas in Washington Gas and Baltimore Gas and Electric territories in Maryland. The license allows WSSC Water to sell natural gas to Montgomery County to power Ride On buses and some county facilities.
Selling RNG will also generate Renewable Fuel Credits that can be sold for additional revenue, the release said. WSSC Water estimates this will generate an additional $3.2 million per year from selling the credits.
In addition, the bioenergy project will reduce WSSC Water’s greenhouse gas emissions by 13%, according to WSSC Water.
According to Yambrach, once the project is complete in the fall of 2024, the county’s Ride On fleet will start to be powered by the methane gas produced from waste flushed down the toilet.
Yambrach told MoCo360 that using RNG is just another initiative the county is taking to reduce its carbon footprint. There are currently four fully electric Ride On buses that run on a single charge per day. Yambrach added that the county will soon see hydrogen powered buses, too.