Variability of driving conditions and its effect on charging time for urban battery electric buses

Due to growing environmental concerns and stringent vehicle emissions regulations, there is a constant urge in the automotive industry to move towards electrified propulsion systems. Public transportation plays a major role in contributing towards lowering the emission level. Battery electric buses are regarded as a type of promising green mass transportation as they provide the advantage of less greenhouse gas emissions per passenger. However, the electric bus poses a threat of limited range and is not able to drive throughout the day without being charged again. This research focuses on the current bus transit systems in the city of Ann Arbor and investigates the impact of different electrification levels on the final CO2 reduction. Utilizing models of a conventional diesel bus, hybrid electric bus, and battery electric bus, the CO2 emission for each type of transportation bus is estimated. Measured vehicle speed data from various routes under different driving conditions are used to investigate the variability of performance metrics. Finally, recommendations are made for charge requirements of battery electric bus considering the variation in drive conditions.