Impact of Different Charging Methods on Electric Bus Battery Size and Grid Demand

Abstract

This paper presents an agent-based model (ABM) that estimates battery size and electricity grid demand for bus charging infrastructure. The ABM considers four charging methods: overnight charging (ONC), end-line charging (ELC), occasionally fast charging (OFC), and wireless charging (WLC). The model accurately captures the energy consumption and charge load of battery electric buses (BEBs) by incorporating GPS coordinates, average speed, and temperature profiles. A case study is conducted on a bus route in Cardiff, UK, to showcase the functionality of the ABM. The results of simulations demonstrate significant reductions in electric bus battery sizes for different charging methods. For example, end-line charging reduces battery size by 235 kWh per bus compared to overnight charging. Occasionally fast charging and wireless charging achieve even lower capacities of 86 kWh and 69 kWh, respectively, however, these charging methods lead to higher and more fluctuating grid loads, resulting in a poor load factor. In summary, this ABM provides a practical tool for infrastructure planners. The case study illustrates its effectiveness in optimizing battery size and evaluating grid demand for BEB charging infrastructure. The findings provide critical directions for both bus operator shifting towards electrification of their fleets and city planners responsible for the deployment of related charging infrastructure.