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We depend on drivers and technicians to let us know the pros and cons of the buses.

They drive and work on them every day.” —Michael Warner, Cobb County (Georgia) School District

DIESEL REMAINS A LEADING OPTION Even as districts consider electric and propane, diesel has also become exponentially cleaner in recent years. Allen Schaeffer, executive director of the Diesel Technology Forum, said that 40 percent of school buses rolling on the road today—a total of 208,000 vehicles— are equipped with the newest generation diesel engine. When deciding on new bus purchases, fleet managers can just stick with a cleaner version of the “reliable and durable” diesel technology they’ve long used, in Schaeffer’s view. Renewable diesel is an option for schools that want

to further reduce their emissions, while they “don’t have to buy charging infrastructure and don’t have to retrain their mechanics,” Schaeffer added. Finnish company Neste, for instance is the world’s largest producer of renewable fuels and has ramped up its distribution of renewable diesel in the U.S. Diesel on the market also includes blends of up to 20

percent biofuels (known as B20), and in experimental programs, buses are running on 100 percent biodiesel (B100). Tat fuel is all plant oil or animal fat, but such pure biodiesel is lower in energy, and raises other mainte- nance and operational issues. “Tat’s an exciting next chapter for diesel,” Schaeffer

said. “It’s a proven concept. Te fuel is a lot cleaner and emissions are dramatically reduced.”

WORKING WITH CNG While Fremont in Northern California invested heavily in CNG buses, primarily because of state incentives, the Jordan School District in Utah started buying CNG 20 years ago, “before it was trendy.” Jordan bought those buses because, at that time, they were so much cleaner than diesel. “Now that is not as much of an issue, since diesel has become drastically more efficient and cleaner,” said

52 School Transportation News • JANUARY 2019

Jordan Transportation Director Herb Jensen. His district still relies heavily on CNG, in part because of grants that support it. But he said those grants more often favor other fuel sources. Jensen said CNG buses cost the district about $28,000

more than diesel buses, but he “aggressively” seeks grants to help, and he has received more than $3 million in grants in seven years. Each bus saves about $7,000 in fuel per year compared to diesel, meaning there is an average pay-back period of about four years, even without grants, he said. “We purchase CNG buses when we can, but there are some situations where a diesel bus fits our needs better,” Jensen added. “When we purchase buses to use for field trips, it makes sense for us to purchase diesel transit style rear-engine buses, so we can have undercarriage storage. CNG buses utilize that area under the bus for the multiple fuel tanks.”

MAKING THE TRANSITION Ultimately, fleet managers who decide what fuels to use need to balance the immediate and short-term needs and finances of their district, with planning for a future that may look drastically different. Tat means there may be widespread electrification infrastructure or different emissions regulations.

Cobb County Schools near Atlanta is aiming for a fleet that is about a third diesel, a third gasoline and a third propane, thanks in part to new incentives for alternative fuels, according to Michael Warner, associate director of fleet maintenance. Warner said the district looks at data on cost of fuels and maintenance over the bus life cycle. But that is not the only deciding factor. “We depend on the drivers and technicians to let us know pros and cons of the buses,” Warner said. After all, “they drive and work on them every day.” ●

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