Most Americans depend on gasoline-powered vehicles for their personal travel, but when it comes to mass transit and freight, diesel power moves the nation.

Anyone who has sat in traffic behind a diesel-fueled bus or big truck knows the fumes can be unpleasant. Burning petroleum diesel also produces harmful emissions, according to Mississippi State University biological engineer San Fernando.

“MSU biological and chemical engineers are working with several alternative fuel sources that have the potential to reduce both harmful emissions and U.S. dependence on imported oil,” he said.

Fernando is working with biodiesel, an alternative fuel produced at several Mississippi facilities. Biodiesel, is usually a refined vegetable oil such as soybean oil that has been put through a chemical process.

“Blending biodiesel with petroleum diesel reduces most of the harmful emissions,” he said. “There is a minimal increase in nitrogen oxide emissions, and research is under way to find ways to reduce their output.”

Children’s exposure to emissions from diesel-powered school buses is a concern, and the use of biodiesel is seen as a way to reduce health risks.

Every day, about 440,000 yellow school buses transport about 24 million children to and from schools and school-related activities, according to the National Biodiesel Board Web site, http://www.biodiesel.org. The NBB is the trade association representing the biodiesel industry and helps coordinate research and development. State soybean commodity groups founded the board in 1992.

“Pollution from diesel vehicles has health implications for everyone, especially children. The use of biodiesel can reduce that threat,” said Amber Thurlo Pearson, a spokesperson for the NBB. “Because it works in any diesel engine with few or no modifications, biodiesel offers schools a relatively inexpensive option for an immediate solution to air quality concerns.”

About 200 school bus fleets nationwide are using at least a B2 biodiesel blend in their buses, she added. The biodiesel available commercially is a blend of pure biodiesel and petroleum diesel. A blend containing 2 percent biodiesel is referred to as B2.

Mississippi’s Lauderdale County School System is using biodiesel in its bus fleet. Since 2003, the Lauderdale system has been running several of its buses on a B10 biodiesel blend and there have been no problems with the buses running on biodiesel, said Roger Wright, transportation director for the school district.

“We’ve seen no differences from a maintenance standpoint in the vehicles running on regular diesel and the ones using the biodiesel blend,” he said. One positive change he has noticed is the cleaner exhaust pipes on the buses with the biodiesel blend.

“They are cleaner than what you usually see on diesel vehicles,” he said.

Soybean producers see use of biodiesel in school bus fleets as a way to both reduce harmful emissions and strengthen demand for their crops.

“Biodiesel has been in use for several years and has been shown to produce fewer harmful emissions than pure petroleum diesel,” said Morgan Beckham, a Leland, Miss., soybean producer and member of the Mississippi Soybean Promotion Board. “School bus fleets are just one of the uses for a product that can reduce demand for foreign oil while increasing demand for U.S. grown crops.”