Plug-in Hybrid School Bus

Lake Chelan School District (LCSD) in North Central Washington is one of 19 districts in 11 states contracted to receive a hybrid (diesel and electric) school bus in 2007 from IC Corporation. The bus will be configured for plug-in hybrid electric technology; when not in electric mode it will run on low-sulfur diesel blended with biodiesel. The Port of Chelan County’s Advanced Vehicle Innovations (AVI) assisted the school district with this project.

BACKGROUND

Since 2003, LCSD transportation supervisor Scott Logan has been involved with a national buyers’ consortium working to acquire hybrid school buses: developing product specifications, seeking vendors and coordinating funding requests. The Hybrid Electric School Bus (HESB) Project has been facilitated by Advanced Energy, a nonprofit in Raleigh, NC. Advanced Energy awarded a bid to IC Corp. for 19 buses. IC is a subsidiary of International Truck & Engine and is partnering with Enova Systems, Inc.

HOW IT WORKS

The powertrain for a hybrid plug-in electric bus couples a V8 diesel engine with an 80-kilowatt hybrid electric drivetrain, incorporating a transmission, batteries and an electric motor. The system recovers kinetic energy during braking, charging the batteries while the bus is slowing down. The bus is plugged in overnight to a standard 120-volt socket, charging the hybrid drive system batteries (minimum storage 28 kilowatt hours). A battery management system allows the batteries to be charged via a connection to the local electric utility (Chelan County PUD). Other equipment monitors the status of the batteries, and a dashboard indicator light tells whether the bus is operating in a “charge depleting” or “charge sustaining” mode. A system including temperature sensors protects components from heat damage due to electrical overload.

BENEFITS AND NEED

Hybrid technology greatly increases fuel efficiency, which lowers fuel costs and reduces the use of fossil fuels. Hybrid vehicles emit fewer pollutants, reducing greenhouse gases which contribute to global warming. The use of biodiesel also decreases fossil fuel use and creates a market for Northwest growers of canola, mustard seed and even used restaurant grease. A school bus, making frequent starts and stops, is an ideal vehicle for hybrid technology, which generates energy from braking. Fuel costs for the school district will be considerably reduced with this bus, which will likely achieve 18 miles per gallon. Standard buses get 5 to 7 miles per gallon of diesel.

COST AND FUNDING

Lake Chelan School District’s plug-in hybrid electric school bus cost about $210,000. The school district has committed $75,000. Other funding sources include $55,000 in federal funding from the HESB consortium, $52,000 from the state Department of Ecology, $10,000 from the Port of Chelan County, and $18,000 from various other private and public sources.