A bi-objective robust optimization model for hybrid E-bus operation under in-motion charging strategy

Electric buses (e-buses) powered solely by batteries face challenges like limited range, long charging times, recurring bigger battery costs, and insufficient infrastructure, hindering their widespread adoption. To address these issues, a hybrid in-motion charging (IMC) enabled e-bus system is proposed where the buses are powered by overhead catenary cables for some parts of their route and supported by a smaller onboard battery for the rest. Thus, significantly reducing range anxiety compared to pure battery-operated e-buses, while also offering greater manoeuvrability due to the onboard battery. A bi-objective optimization framework evaluated the trade-off between total investment cost and the environmental benefits to the near-road population from transitioning to e-buses. To account for uncertainties in energy consumption and power transfer from the catenary cable to the battery, a robust optimization framework was formulated, ensuring resilience under varying field operating conditions. Our model, tested on Delhi’s bus network, indicates that electrifying around 1/5th of the route in the deterministic case and 1/4th under robust planning will ensure uninterrupted e-bus operations. IMC proves more cost-efficient in the long-term, particularly at higher fleet replacement, compared to terminal charging (TC) under similar operational scenarios. This study also recommends key policy measures emerging from Delhi’s case study.