Smart Charging System in a Bus Depot: Cost-Effective Strategy

This study presents a practical approach to quantify the economic benefits of dynamic price-based charging strategies for electric bus operators with overnight depot charging. The replication of the methodology allows for the precise estimation and charging schedule for the specific schedule. However, this work is also designed to target decision makers, allowing them to access the investment in this technology and its integration using the presented results. This paper defines a Mixed-Integer Linear Programming framework to optimize electric bus charging schedules using day-ahead electricity prices, incorporating real-world operational constraints and infrastructure limitations, and presents the potential savings achievable with the implementation of the proposed framework. The methodology includes a benchmark that schedules the charging as soon as possible, thereby replicating uncontrolled charging. Validated with actual operational data from a medium-sized Italian transit company, the model demonstrates substantial cost reductions by strategically shifting charging times to exploit lower-priced energy periods, especially aligning overnight charging with reduced electricity tariffs. The case study with real data from Italy shows a potential reduction of up to 1500 € (9% of the bill) for an 11-bus fleet. Scenario-based analyses highlight potential monthly savings with reductions in energy costs ranging between 7.8% and 15.1%, depending on operational contexts. Sensitivity analyses confirm that the operational variability further enhances cost-saving opportunities, while constrained grid power significantly limits these benefits, showing the impact for an adequately sized charging infrastructure. Also, a table is provided to easily extend the results to other European countries.