A MILP-based Approach to Account for Battery Degradation in Electric Bus Charging Scheduling

Electric buses (e-buses) are a promising solution for transitioning into electrified transportation. With that being said, a rigorous planning needs to be conducted in order not to face significant costs in e-bus fleet operations. In addition to the electricity cost of charging, the battery degradation costs could make up a significant portion of the running costs. In this regard, we propose a mixed-integer linear programming (MILP)-based approach to integrate battery degradation costs into a cost-optimal e-bus charging scheduling problem. Within the approach, we adopt an existing battery degradation model from the literature and approximate it using linear regression and piecewise-linear approximation. Numerical case studies conducted on a part of the shuttle bus service of National University of Singapore reveal that the proposed approach approximates the actual degradation model with a good accuracy and enables up to 61.92% reduction in battery degradation costs compared to the benchmark e-bus charging approaches.