Modelling benefit-to-cost ratio for initial phase electrification using battery electric bus

Abstract

In light of growing global concern regarding environmental pollution, greenhouse gas emission and fast-depleting petroleum resources, electric buses are being considered as an integral part of future urban transportation system. However, substantial financial resources required for complete transition from conventional fuel-driven buses to electric buses means that this process will take place progressively. We have developed an optimization framework to assist in decision-making during the initial phase of transitioning to electric buses while working within financial constraints. Our approach focuses on a route-specific performance metric, the benefit-to-cost (B/C) ratio, which maximizes fuel savings and emissions reduction when transitioning to electric buses, all while respecting the limitations of available resources. The model identifies the set of bus routes to be electrified, along with the locations of electrified terminals. The proposed model was tested on the extensive public bus network of Delhi, India for two scenarios: compressed natural gas (CNG)-to-electric and diesel-to-electric bus transitions. Additionally, sensitivity analysis was conducted to evaluate how the available electrification budget and charging power affect the benefit-to-cost ratio and decisions related to route and terminal electrification. To fully realize the environmental benefits of electric buses, it is essential for the bus electrification policy to align with a shift from carbon-intensive energy sources to cleaner alternatives. Our study for Delhi suggests that a minimum of 30% of the electricity should come from clean energy sources to maximize the environmental benefits of bus electrification. This framework can thus serve as a useful tool to public transit agencies when planning the initial phases of the bus electrification.