Optimal battery electric bus planning and its economic and environmental impacts

Battery electric buses (BEB) have attracted attention as future eco-friendly public transit. However, planning a large-scale BEB system is challenging, with additional constraints related to charging facilities and batteries. We present a bi-objective decision-making framework to minimize the overall cost and greenhouse gas emissions, robust to operational uncertainty and applicable to various real-world scenarios. We propose a tractable queuing-theoretic solution method to determine three optimal planning factors: charging infrastructure, fleet size, and battery capacity. We demonstrate the proposed method in a numerical example and derive the following practical insights. First, sharing chargers among BEBs assigned to different routes is beneficial, but pooling BEB fleets does not always guarantee economic and environmental benefits. Second, the optimal BEB system, while not the most economically preferable option, provides the maximum environmental benefit compared to conventional non-fully-electrified systems. Additionally, through a sensitivity study, we show the necessity of accurately evaluating electricity consumption stochasticity