An Iowa State University researcher says a study of hybrid school buses shows some promise for decreasing fuel costs and pollution, if mechanical problems with the buses can be fixed. Two hyrbid-electric school buses were purchased for the Nevada and Sigourney school districts and run alongside regular buses.

Shauna Hallmark of the I.S.U. Institute for Transportation, says there were problems with the batteries on the buses holding a charge.

Hallmark says the charging system does some charging from the bus diesel engine, but the majority of the charging has to be done by plugging in the bus. And she says something was not working, so the batter did not charge.

The hyrbid-buses got 30% better mileage in Nevada and 36% better in Sigourney. Hallmark says the savings could help offset the increased cost of buying the specialized buses. She says diesel fuel is occasionally up to $4.00-a-gallon, and a school bus gets about six miles to the gallon.

While she hasn’t done a cost estimate analysis, she believes districts could recoup the cost of the bus in fuel savings. Hallmark says other hybrid systems used in cars and transit buses use only the engine to charge the battery. Hallmark says the type of technology used could be the deciding factor in whether schools would buy hybrids.

She says it depends on the next step for the next generation bus, and that hasn’t been decided yet. Hallmark says if they put the same technology in school buses that’s used in transit buses, then she thinks it would work. Hallmark says it is a promising idea, and there is more to the use of hybrids than saving money.

Hallmark says it’s not just fuel economy, it’s also the emissions put out by the buses. She says buses put out a lot of the small fine black particulates that pollute the air, and the hybrid buses would reduce the amount of pollution the kids are exposed to. Researchers received grants that paid for most of the 217-thousand dollar cost of each bus. The districts each paid about 70-thousand dollars — which is about the cost of a conventional bus.