Evaluating wireless charging configurations for electric bus systems: A degradation-aware comparison and electricity-pricing implications

Wireless power transfer (WPT) expands in-service charging opportunities for battery electric buses (BEBs), but its economic value depends on interactions among battery capacity, infrastructure deployment, charging schedules, battery degradation, and electricity prices. This study develops a unified optimization framework to compare plug-in charging, static wireless charging (SWC), dynamic wireless charging (DWC), and hybrid WPT under consistent operating and cost assumptions. The framework jointly determines battery capacity, WPT facility locations, and charging schedules while accounting for electricity, infrastructure, cycle-degradation, and calendar-degradation costs. The framework is applied to a case study based on the Tower Transit bus network in Singapore. Under the baseline tariff, DWC reduces the minimum feasible battery capacity from 240 kWh to 40 kWh, while the costs at the four candidate minima differ by only 0.66%. DWC provides the additional charging opportunities required for extreme battery downsizing, whereas the hybrid configuration relies mainly on SWC and uses limited DWC to close residual energy gaps. Lower daytime electricity prices favor smaller batteries and WPT deployment, while higher prices cause WPT to exit. An illustrative bus-specific tariff reduces daily system cost by 3.71% while maintaining its baseline electricity payment. Further sensitivity analysis shows that lower WPT costs and higher efficiency favor smaller hybrid systems, whereas lower battery prices and longer cycle life favor larger batteries and reduce the cost advantage of planning with WPT. Overall, WPT primarily expands battery design flexibility rather than producing a large cost advantage at the candidate minima, and its adoption depends on coordinated battery, infrastructure, and tariff planning.