Combatting climate change requires innovation from all industries, including transportation. Guided by a commitment to cleaner air, the Greater Cleveland Regional Transit Authority is replacing its diesel buses with a fleet of compressed natural gas (CNG) vehicles.

GCRTA’s current operation consists of 238 CNG buses and 73 diesel vehicles. A recently-awarded $2.7 million grant from Ohio’s Diesel Emission Reduction Grant (DERG) program will swap out five more diesel-powered buses with a like number of environmentally-friendly CNG bus models.

GCRTA Triskett Bus Maintenance FacilityAnnounced on Jan. 17, the Ohio Environmental Protection Agency (OEPA) grant will fund purchase of the new 40-foot transit buses—the vehicles will replace a phalanx of aging diesel burners nearing the end of their service life, says GCRTA quality insurance manager Brian Temming.

Funding for the DERG initiative is provided by the U.S. Department of Transportation Federal Highway Administration’s Congestion Mitigation and Air Quality Improvement (CMAQ) Program.

Per terms of the grant, the old buses must be taken completely out of commission, notes Temming.

“We have to destroy their engines so they can’t be salvaged,” he explains. “We have our people in the shop drill a hole through the engine block, then send pictures to the [Ohio Department of Transportation].”

Green benefits
Compressed natural gas buses can significantly decrease the carbon footprint of public transit, its proponents maintain. CNG buses are purpose-built to run on compressed natural gas, which is cooled after compression to make it usable as fuel.

A key advantage of CNG is its lower cost compared to diesel. In April of 2024, the average per gallon price of diesel was $3.50, while CNG was $2.90 per gallon. Yet, CNG buses come at higher upfront cost. According to the U.S. Department of Energy, CNG buses typically cost $25,000 to $30,000 more than conventional buses, a price offset by government incentives like the DERG grants.

Refueling a CNG RTA busEmission reduction is the headline-grabber for CNG usage. Diesel combustion produces about 12 times more carbon dioxide than CNG for the same amount of fuel burned. GCRTA reports a 15% reduction in tailpipe emissions with its CNG fleet compared to diesel—the transportation organization already has CNG fueling stations at its Hayden bus facility in East Cleveland and Triskett maintenance garage in Lakewood.

Cleveland neighborhoods will also benefit from the more subdued operation of the new CNG buses, which are up to 10 decibels quieter than diesel models.

“These buses are more like a car riding down a roadway then a Mack truck coming down the road with a large rumbling sound,” Temming says. “This adds to rider comfort as well, as riders won’t be getting the vibrations they do with diesel engines.”

An emissions-free future?
GCRTA follows Greenhouse Gas Protocol standards to measure and manage bus emissions. According to these guidelines, a diesel bus emits 91 metric tons of cardon dioxide annually, compared to 77 tons per year for a CNG vehicle.

“GCRTA is always looking for ways to proactively reduce emissions across all aspects of our operations,” GCRTA deputy general manager of operations Floun’say Caver said in a press release. “This grant funding from the DERG program not only allows us to modernize our bus fleet, but also demonstrates our continued commitment to providing cleaner, more sustainable transportation for our community. We greatly appreciate the continued support provided by OEPA for our bus improvement program.”

GCRTA will replace five of its diesel buses with Compressed Natural Gas (CNG) buses.The switch to CNG supports Cleveland’s goals to decarbonize all transportation emissions by 2050, as stated in the city’s climate action plan. Christina Yoka, chief of pollution outreach for the City of Cleveland, points to CNG’s benefits as well as its drawbacks.

“There are fewer emissions with CNG as compared to diesel, but like with any transportation source, there will still be an impact,” says Yoka. “In terms of air quality, transportation is a big contributor to pollution. Any projects in place to reduce that will help us achieve our overall goals.”

Decarbonizing transportation emissions means turning to energy sources beyond CNG, including electric power and renewable natural gas, adds Yoka.

A $10.6 million grant from the Federal Transit Administration (FTA), awarded last July, will allow GCRTA to purchase 10 battery-electric buses. In addition, the pilot grant supports installation of three electric vehicle charging stations within the GCRTA service area, says Temming.

Due to FTA regulations requiring 12 years or 500,000 miles of service for grant-funded buses, Cleveland's newer diesel buses cannot be replaced until 2033. However, GCRTA leadership remains excited about the possibility of a zero-emissions bus fleet.

“We’re considering electric battery and hydrogen buses, too,” Temming says. “We’ll be evaluating that technology and also looking at the customer experience.”