A hybrid school bus from Napa Valley USD.

A hybrid school bus from Napa Valley USD.

About five years ago, the Napa Valley Unified School District (NVUSD) became the first in California, and one of only eight school districts in the U.S., to operate a hybrid school bus with the ability to double fuel efficiency and reduce emissions by up to 90 percent.

The new bus came courtesy of a nationwide initiative called the Plug-In Hybrid Electric School Bus Project. The exterior of the hybrid school bus looks the same as a standard school bus, but features Enova’s Charge Depleting System, or “Plug In.”

“The bus gets more than double the mpg of the same bus with a diesel engine,” said Ralph Knight, director of transportation for NVUSD. “It has done a great job over all these years, and we would add more of them if the price was right.”

Alternative-Fuel Vehicle Savings Significant for NVUSD

The 72-unit school bus fleet also operates many other alternative-fuel vehicles, including 31 John Deere/Bird compressed natural gas (CNG) units, four Cummins/Bird CNGs, three Ford/Collins/Azure special needs hybrids, one Ford/Collins CNG special needs, and five Thomas/Eaton C2e hybrids.

About 65 buses are used throughout the school year. The only buses not used include the oldest and “smoking” buses. Knight keeps all of the CNG units on the road.

“All of our alternative-fueled buses have been a major plus to our operation. The fuel savings alone has been more than $26,800 over the past five years with the plug-in hybrid,” explained Knight, who has worked at NVUSD for 18 years, with a total of 43 years in the yellow bus industry.

The CNG buses have saved the district about $105,000 in fuel costs each year when comparing CNG fuel to diesel prices. The Ford/Azure hybrids save Knight the cost difference between gasoline and diesel, which is about 50 cents per gallon. The Thomas/Eaton hybrids achieve about 10 mpg, which is also a savings of 85 percent over a standard diesel bus.

CNGs and Hybrids Keep Working Beyond 200K Miles

Knight has been extremely pleased with the John Deere 8.1L CNG school buses the district previously added to the fleet. All of the buses now have 200,000 to 300,000 miles on them and show no major problems.

“I can’t say enough about the Deere 8.1L CNG engine. Being an early user of the Deere was a dream all around,” Knight said. “And, Deere provided many hours of great training to the shop to get the program up and running.”

He is also thankful that Deere is still there when needed for the shop, and hopes to see that particular engine come back to the school bus world.

Another bright spot in the alt-fuel fleet are the Collins-body special needs buses, based on the Ford E-450 chassis, with Balance drive by Azure. And, according to Knight, these vehicles have done everything the district hoped for.

“The cost of operation has been a plus for these buses,” he said. “They have not been a problem for us at all, and the drivers love to drive the greener buses.”

Knight also reports saving in other areas as well, including vehicle maintenance. Thanks to more modern systems (and excellent fuel efficiency) preventive maintenance work, such as oil changes, are required less often.

Changing the Way a Fleet Thinks with Alt-Fuel Vehicles

District personnel and bus drivers alike love the alt-fuel fleet vehicles. “We have been very happy with all of our alternative buses at this time,” Knight said. “It was new technology to come into our operation. It took training for the shop and drivers for us to gain the best possible mpg.”

A major selling point for the district’s drivers included the new engine technology. And, according to Knight, it actually made the drivers try to get the best mpg out of the bus as possible.

“Overall, it has been a great move on the district’s part to allow me to replace all our old buses with clean fuel buses,” he said. “It has been a major savings for the district in total fuel cost.”

Knight also pointed out that implementing the alternative-fueled buses changed the way the NVUSD fleet now thinks. Saving fuel costs, decreasing vehicle emissions, and letting the area’s school children ride in a vehicle with the newest and best technology not only means saving money, but making a difference in the community as well.

District Acquires New Hybrid-Electric School Buses

The district acquired five Thomas/Eaton C2e hybrid-electric school buses in 2012. The buses are so high tech, Knight said, that “it’s like driving around in your family car. It is great to see this type of technology moving into the school bus world,” he added.

The new purchase hasn’t come without a bit of controversy, however. Since the vehicles arrived on the scene, they have remained out of service because the California Highway Patrol (CHP) maintains that the buses’ green rub rails do not comply with state and national standards. Note: these standards are recommendations only, not law.

According to a section of Title 13 in the California Code of Regulations, the exterior of a school bus must be yellow, with the exception of bumpers, grilles, lamp bodies, and other accessories. Title 13 also specifies that a bus’ moldings and rub rails “may be black.”   

Knight says that, while he understands the California Title 13 requirements, a statutory provision allows for exemptions. He is currently working with the CHP and the proper officials to get the buses out on the road. In fact, NVUSD has applied for funds to get eight more Thomas C2e and two transit CNG school buses.

“Alternative fuels are here to stay in the yellow world,” Knight stated. “Buses are doing a great job out here in the real operational world. The buses run every day and do the job that we want for a safe and clean ride for our students.”

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Cheryl Knight

Cheryl Knight


Cheryl Knight has more than 20 years of editing and writing experience on topics ranging from advanced technology, to automotive fleet management, to business management.

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