Variability in Driving Conditions and its Impact on Energy Consumption of Urban Battery Electric and Hybrid Buses

Growing environmental concerns and stringent vehicle emissions regulations has created an urge in the automotive industry to move towards electrified propulsion systems. Reducing and eliminating the emission from public transportation vehicles 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 faces a problem of limited range and is not able to drive throughout the day without being recharged. This research studies a public bus transit system example which servicing the city of Ann Arbor in Michigan and investigates the impact of different electrification levels on the final CO₂ reduction. Utilizing models of a conventional diesel, hybrid electric, and battery electric bus, the CO₂ emission for each type of transportation bus is estimated. Vehicle speed data collected from various bus drives over different routes under different driving conditions are used to investigate the variability of drive conditions on performance metrics. Finally, recommendations are made for charge requirements of battery electric buses considering the variation in drive conditions which can result to an increase in the required charging time as high as 20%.