Evaluating the sustainability of electric bus during operation using field data - A case study of electric buses in Guangzhou, China

Abstract

Environmental sustainability is a crucial issue for all human beings, and vehicle emissions significantly contribute to climate change. This has prompted many countries, including China, to focus on electrifying transportation. This study evaluated the sustainable performance of electric buses (EBs) in Guangzhou, China, by quantifying their carbon dioxide emissions throughout their life cycle using a life cycle assessment (LCA) methodology. The operation and charging phase is highlighted, with analysis based on field data from over 500 electric buses in operation during 2021, where the electricity consumption rate was 90.15 kWh/100km. The results show that the life cycle CO2 emissions are 1097.07 g CO2/km/vehicle, including stages of battery manufacturing, powertrain manufacturing, glider manufacturing and assembly, operation and charging, and end-of-life. The operation and charging stage contributes the most to the lifespan CO2 emissions at 69.6%, due to the carbon-intensive energy mix of the local grid. Additionally, lifespan emissions of EBs are predicted to be reduced by 15.28% by 2030, when China’s carbon peak goal will be achieved. A comparison between EBs and conventional internal combustion engine (ICE) buses demonstrates a significant reduction in CO2 emissions with EBs. However, considering regional differences in grid carbon intensity across China, the overall benefit of bus electrification depends on transitioning to a greener energy grid nationwide. Therefore, the development of hybrid engines and improvements to the energy grid are still crucial.