Diesel buses and personal vehicle trips for school transportation emit millions of tons of greenhouse gases per year into the environment, which contribute to global warming, and expose children to harmful pollutants that can affect their health and academic performance. What would it take for the yellow school bus--and school transportation…

In recent years, school districts have converted portions of their bus fleets to cleaner-burning, sometimes cheaper, alternative fossil fuels, such as compressed natural gas or propane. Others have adopted biodiesel, which combines regular diesel with fuel derived from organic sources, usually vegetable oils or animal fats. The number of biodiesel…