A Cherriots bus powered by renewable natural gas. (Courtesy/Cherriots)
More than half of Cherriots buses now get their fuel from landfills.
In December last year, the transit provider for the Salem area switched the fuel source for 34 buses from compressed natural gas to renewable natural gas. The two fuels are nearly identical chemically and riders likely didn’t notice any change.
But the switch in more than half of Cherriot’s 64-bus fleet is a big part of the transit agency’s plan to reduce greenhouse gas emissions while also boosting its bottom line.
Renewable natural gas is produced by capturing and processing methane, a greenhouse gas more potent than carbon dioxide, from agricultural waste or food decaying in landfills. Buses powered by renewable natural gas still emit carbon dioxide. But using the fuel means capturing methane that would otherwise be released into the atmosphere.
Transit agencies across the country, including the New York Metropolitan Transportation Authority, have been turning to the fuel for environmental as well as financial benefits.
“By flipping on the switch to renewable natural gas, we instantaneously cleaned up our fleet,” said Ian Davidson, president of Cherriot board.
Cherriots now claims to have the cleanest bus fleet. The switch fits in with state and local goals to reduce greenhouse gas emissions. But Davidson said Cherriots wants to do more.
While there are fewer overall greenhouse gas emissions associated with Cherriots, the transit service still puts diesel buses on the road that emit carbon dioxide out of their tailpipes. Davidson said there are plans to phase out the diesel buses, hire a sustainability coordinator and find other ways to reduce Cherriots’ carbon footprint.
Earlier this year, Cherriots received a federal grant to buy five electric buses that could hit the road next year.
But Davidson said that because buses are expensive to replace and last for a decade or more, Cherriots needs to proceed carefully as it seeks to continue driving down emissions from its fleet.
‘Ready to go’
Gregg Thompson, Cherriots maintenance manager, said that in 1998 the transit agency began replacing its diesel buses with those that run on compressed natural gas. The fuel is used in place of gasoline and produces fewer air pollutants than diesel.
Renewable natural gas is nearly chemically identical to compressed natural gas and the two can be used interchangeably. It’s also delivered to Cherriots using NW Natural’s pipeline, said Thompson.
“There’s no difference in fuel economy,” said Thompson. “There’s no difference in tailpipe emissions.”
But renewable natural gas comes with other environmental and financial benefits.
Oregon gives tax credits to companies for using renewable natural gas. Last year, Cherriots signed a five-year contract with renewable fuel company U.S. Gain to provide the gas and manage the tax credits. Under the contract, the transit agency gets 40 cents per ton of renewable natural gas it purchases, which Thompson said works out to about $200,000 annually.
While burning natural gas creates carbon emissions, using its renewable form means less overall greenhouse gas emissions. The process captures methane that would otherwise be emitted into the atmosphere from dairies, landfills and wastewater treatment plants.
“You can say that you’re carbon negative because the amount of methane that you’re capturing compared to the amount that you’re producing from your tailpipe is less,” said Thompson.
According to a statement from Cherriots, using renewable natural gas reduces tailpipe smog emissions by more than 90% and greenhouse gas emissions by more than 40%.
Transportation is the largest source of greenhouse gas emissions in Oregon. Last year, Salem’s Community Greenhouse Gas Inventory found the city had one of the highest concentrations of transportation emissions of Oregon cities.
Switching vehicles to more environmental fuels like renewable natural gas will be important as the city develops its climate action plan, said Connor Reiten, government and community affairs manager for NW Natural.
“Renewable natural gas has a huge role to play because it’s mature and ready to go,” said Reiten, who sits on the city’s climate task force.
Chris Hagen, associate professor of energy systems engineering at Oregon State University–Cascades, said that while the technology for renewable natural gas is mature there could be competition for the fuel as more communities along the West Coast decarbonize.
“There’s not that many dairies and landfills relative to our consumption of fossil fuels,” he said.
Electric or renewable natural gas?
A report from Bloomberg New Energy Finance estimates that in 2017 the number of electric buses worldwide grew to about 385,000. However, 99% of those are in China and U.S. cities have been slow to adopt the technology.
Adopting it hasn’t always been smooth. The Los Angeles Times reported in 2018 that electric buses used locally experienced frequent breakdowns and other mechanical issues.
Hagen said that determining whether running buses using renewable natural gas or electricity is better for the environment is complicated. He said that source of the electricity used to power matters as well as how the buses’ batteries are disposed of matter. But he said that he considers renewable natural gas better because it captures methane.
“It’s a completely new fuel technology for our staff,” said Davidson of the electric buses Cherriots will get next year. “There’s always going to be a learning curve. And so it would be inappropriate and unwise of us to just jump fully in without fully testing it.”
Cherriots plans to debut its electric buses on Route 11, a busy route along Northeast Lancaster Drive. Davidson said Cherriots will push the buses “to the limit” and monitor them to see how well they run.
He said that as Cherriots rewrites its vehicle acquisition policy it’ll also be looking at issues such as how much space charging stations need. If Cherriots decided to invest in electric buses, it could mean the agency would need a new depot, he said.
But in the meantime, Davidson said the renewable natural gas buses are moving Cherriots in the right direction.
“We’re thrilled with it, but we’re not satisfied with it,” said Davidson. “We want to be 100% clean.”
Contact reporter Jake Thomas at 503-575-1251 or [email protected] or @jakethomas2009.
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