Biodiesel causes more pollution, new study concludes

BOISE – Preliminary findings of a local study say burning biodiesel to cut vehicle exhaust may actually produce more air pollution.

“They’re not exactly what we expected,” said June Ramsdell, the regional airshed manager for the Idaho Department of Environmental Quality.

She added that the results mean more research must be conducted into the effects of biodiesel, which is fuel mixed with vegetable oil from soybeans or recycled restaurant grease.

Officials have promoted biodiesel as an environmentally friendly and renewable energy source. Diesel contributes both to wintertime particulate pollution and summer ozone pollution that hangs over the valley.

Local air quality officials say several factors – such as contaminated fuel – may have affected the findings, which show some pollution at levels three times higher for biodiesel.

“To throw out the national research is probably not the way to go,” Ramsdell said.

Outside experts, including the U.S. Environmental Protection Agency and the University of Idaho, are reviewing the findings. The study was conducted earlier this year on about 200 Meridian school buses, which ran on B20, a mixture of 80 percent diesel and 20 percent biological oil.

This study, funded by a federal grant and the Community Planning Association of Southwest Idaho, differed from others in that emissions were tested as the buses slowly rolled past a testing station. Other studies, which found lower pollution levels from biodiesel, hooked machines to engines and tested emissions at levels varying from idling to highway speeds.

Statewide, about 200,000 gallons of biodiesel were sold in 2003, the first full year that it was available.

The state Energy Division has a program that pays the difference in cost between diesel and biodiesel to participating agencies. The B20 blend costs about 15 cents more per gallon than regular diesel.