Modeling Fuel Consumption of Hybrid Electric Buses: Model Development and Comparison with Conventional Buses

Electric hybridization technologies appear to be one of the most promising approaches to improving the energy efficiency of buses; however, this improvement has not been systematically quantified. A fuel consumption model is essential for capturing fuel consumption behavior accurately and quantifying the fuel benefits of hybrid buses. Consequently, the objective of this study was to develop a fuel consumption model for hybrid buses on the basis of the framework of the Virginia Tech Transportation Institute’s comprehensive power-based fuel consumption model and then to quantify the benefits associated with hybridization technologies relative to conventional diesel bus operations. The model estimates were demonstrated to be consistent with in-field measurements, and the optimum fuel economy cruise speed was demonstrated to be approximately 50 km/h. The results demonstrate that hybrid buses consumed less fuel overall, while heavier buses and higher passenger loads may have reduced the fuel savings. The results also reveal that more fuel savings could be achieved for cruise and stop-and-go activity compared with idling behavior and that stop-and-go operation generated the highest level of fuel efficiency benefits. The conclusions of this paper can support bus planning applications to achieve fleet fuel savings