The first two hybrid school buses in the state have found homes in Iowa school districts.

The nearby Nevada Community School District and Sigourney Community School District, in southeast Iowa, have each received a hybrid school bus to add to their current fleets.

Dennis Kroeger, transportation research specialist for the Center for Transportation Research and Education at Iowa State, helped the two districts obtain the buses from Raleigh, N.C.-based Advanced Energy.

“Our role was to coordinate the specifications and assist in getting funding for the buses and coordinate the purchase,” he said.

Kroeger said CTRE heard about Advanced Energy’s program and notified school districts in Iowa. Nevada and Sigourney both responded.

The hybrid buses will require less fuel than other buses. Kroeger said a typical bus’ gas mileage is about 6 to 6 1/2 miles per gallon. With the hybrids, they hope to achieve about 10 to 11 miles per gallon.

“We’re hoping to see approximately a 40 to 50 percent increase in fuel efficiency,” he said.

The hybrid buses save fuel by switching power to an electric motor when the power of the diesel motor is not needed. At highway speeds, the diesel engine takes over, but the electric motor is used frequently in the city.

In city environments, buses stop frequently, and most of the energy used by a traditional bus is spent accelerating the bus after coming to a stop. The hybrid buses alleviate this problem by using the brakes to recover some of the spent energy.

“The batteries are recharged with the regenerative breaking – starting and stopping,” Kroeger said. “The heat from the brakes, when the brakes are activated, that energy is then channeled in order to keep them in a state of charge.”