Battery-electric transit bus developments and operations: A review

In this article, we review the worldwide developments of battery-electric buses (a) from medium-sized vehicles (e.g., 6.7 m) to heavy-duty vehicles (e.g., 11 m), and (b) from the slow-charging mode (e.g., 6 hours) to the fast-charging mode (e.g., 10 minutes). We also review the worldwide operations of battery-electric buses (a) from 1907 in London, England, the early 1980s in Denver, Colorado, and the early 1990s in Santa Barbara, California, and Chattanooga, Tennessee, to various international cities now, and (b) from less than 20 vehicles in a transit agency to more than 1,000 vehicles. We summarize the experiences and lessons learned from real-world operations. We examine key technical specifications that are critical to the operations of electric bus systems, in particular the operational distance and charging time. Due to a limited operational range of battery-electric buses, three range remedy methods have been proposed: (a) regular (slow) battery charging with backup vehicles equipped with fully charged batteries; (2) battery swapping; and (3) fast opportunity charging during the layover period. We conduct a qualitative analysis on the strengths and weaknesses of each range remedy method. We also analyze the vehicle cost, energy cost, and emissions of transit buses powered by different sources, and examine potential impacts of fast-charging electric buses on the electric grid.