Life cycle carbon footprint of battery electric bus: coupling effects of mileage, energy mix and recycling processes

With the global push toward carbon neutrality, reducing greenhouse gas emissions in the transportation sector has become increasingly urgent. Electric buses represent a promising solution; however, their full life cycle carbon footprint remains underexplored. This study aims to address this gap by quantifying and comparing the life cycle carbon emissions of pure electric buses. A life cycle assessment (LCA) approach is applied to evaluate emissions across the production, usage, and recycling stages. Scenario analyses are conducted to assess the impact of carbon fiber reinforced polymer (CFRP) as a material substitute, variations in electricity generation mix, coal consumption rates, and the extent of recycled material utilization. Results show that buses using nickel manganese cobalt (NMC) battery type C have the lowest life cycle emissions at 55,814.89 kg CO₂-eq, while those with lithium iron phosphate (LFP) battery type A have the highest, reaching 59,364.10 kg CO₂-eq. During the production stage, the primary emission sources are the body, chassis, battery system, and electricity consumption. Substituting steel and aluminum with CFRP increases production emissions by up to 108.6%. However, in the operational phase, CFRP significantly reduces bus weight by 41.99% and cuts operational carbon emissions by 36.49%. In the recycling stage, NMC battery type C yields the highest emission reduction, achieving 14,943.86 kg CO₂-eq, mainly due to the recovery of nickel and lithium compounds. These findings offer valuable insights for optimizing material choices, energy structures, and recycling strategies to support the low-carbon development of electric buses.