Environmental Impacts of Battery Electric Vehicles: Implications of the Cascaded Battery Life Cycle and Yearly Charging Electricity

The environmental performance of battery electric vehicles (BEV) is influenced by their battery size and charging electricity source. Besides, the environmental performance of BEV may consider the changes in the European Union (EU) energy sector and the interest in repurposing used BEV batteries for a second life. This study conducts a Life Cycle Assessment of the environmental impacts of a BEV, considering changes in the EU electricity mix and the repurposing of its Li-ion battery (LiB).
The system boundary covers all the life cycle stages of the BEV, including its repurposed LiB cells, except the use stage of the repurposed LiB. The yearly emission profiles (2020 - 2031) of the EU electricity mix were used to estimate the BEV's well-to-tank (WTT) emissions. These were modelled based on the "Stated Policies Scenarios" for the EU reported in the World Energy Outlook 2019 report. The inventories for vehicle and battery manufacturing were based on secondary data. The ReCiPe 2016 impact assessment method was used. The used BEV battery has been repurposed for second-use in a residential application. The repurposed LiB was modelled considering battery refurbishment and assuming 50% of the used LIB cells are viable for a second lifetime of 10 years. The study also tested the sensitivity to these parameters, considering 10% to 100% cell conversion rate (CCR) and a second lifetime between 1 and 5 years.
The results showed that BEV could reduce 8% in global warming potential (GWP) when future changes (increase in the share of renewable energy sources) in the charging electricity are considered. When recycling is considered, an 11% reduction in GWP was noted and a further 3% for repurposing the used LiB cells. The sensitivity analysis showed that GWP reductions occurred for a lifetime of 10 years for all CCR values. For a 5 years lifetime, GWP reductions started at 40% CCR. However, GWP increases for a lifetime of 1 year for all CCR values.
The results show that available LCA studies on BEV are likely to overestimate the life cycle GWP of current BEV by at least 8% when future electricity sector changes are not considered. Thus, the environmental advantages of BEV are likely minimised. The study also found added benefits of LiB repurposing under certain conditions and confirmed the importance of recycling on BEV's net environmental performance.