School Bus Biodiesel (B20) NOx Emissions Testing

This study investigated the impact of biodiesel (B20: 20 percent biodiesel, 80 percengt conventional diesel) on the oxides of nitrogen (NOx) emissions emitted from diesel school buses. Two drive cycles were developed based on the real rural and urban drive cycle data collectedusing a global posiitoning system (GPS). The developed synthetic drive cycles captured the important characteristics of real worl driving conditions for replication on a tes track. Five buses were selected according to the current model year mix in texxas and were driven following the developed drive cycles for three fuel blends -- texas Low-Emissions Diesel-compliant as base fuel, B20 market blend, and B20 all soy. A state-of-the-art portable emission measurement system (PEMS) unit was used to measure the NOx emission along with other emissions, ambient weather condition, GPS readings, and vehicle engine data. The data were cleaned and aggregated to represent the current Texas school bus fleet and rural/urban mix of miles driven. The results of statistical analysis showed that using B20 had no significant effect on the level of NOx emissions emitted by the school buses.