Two Iowa school districts are helping test the use of batteries to power buses, with mixed results over the past three years. Steve Jennings drives a big yellow bus for the Nevada School District. The motor of the bus starts up with the power of diesel fuel, but once on the road the vehicle starts drawing power from two big batteries underneath the bus which charged overnight, in hopes of using less diesel.
“You know, they were talking about getting 16 to18 miles per gallon,” Jennings says. “We’re not getting that. We’re getting between 9 and 10 for a monthly average.” School buses that run strictly on diesel normally get about six-miles-to-the-gallon. Shauna Hallmaker, an environmental and transportation professor at Iowa State University, says it will take “several years” to get back what’s been invested in the battery-powered buses that’re in use in Nevada and in the Sigourney School Districts.
“They had a lot of maintenance issue on the buses, so the charging system didn’t always work the way it should. It went out. They had to get repaired several times for both school districts,” Hallmark says. “When the charging system goes out, they are able to turn the bus off and turn it just to a regular bus, so just it’s operating on the internal combustion system, so it’s not completely out of service, but while they’re waiting to get it fixed, it’s not running as a hybrid.”
The two buses, which are equipped with plug-in rechargeable batteries, cost about 80-thousand dollars more than a traditional school bus. Richard Scott recently retired as transportation director for the Nevada School District. He says the biggest problem has been the life of the battery because after the bus goes 35 miles, the charge in the batteries is gone.
“We ran it the first year out in the country — regular routes, activities, every thing. The second year we brought it in town and just strictly did in town, plus activity trips,” he says. “It was a benefit better than it was out in the country. It does not like Iowa muddy roads, point blank. It just pulls the battery (power) down something fierce.” Iowa’s cold winters have been a major drain on the bus batteries, too. Jennings, the Nevada school bus driver, says there’s another down-side to using the combination of diesel-fuel and battery-power for the bus during the winter.
“The diesel engine never warms up until you’ve been on the road for an hour and then you start getting heat in there,” Jennings says. “So we had to go to auxiliary heat in the bus in order to keep the students warm in the winter time.”
The Nevada and Sigourney School Districts each paid about $70,000 for the hybrid buses being used in the experiment, which is the cost of a traditional bus. The districts split a $217,000 federal grant to cover the additional costs for the two buses.