Abstract
Electric vehicles (EVs), including battery electric buses (BEBs), represent a promising solution for reducing greenhouse gas (GHG) and air pollution emissions. However, their environmental benefits are contingent on the energy sources used for charging. This study conducts a well-to-wheel (WtW) life cycle assessment of BEBs in the City of Johannesburg to compare the carbon dioxide (CO2), nitrogen oxides (NOx), and sulphur dioxide (SO2) emissions of BEBs and diesel buses on Metrobus routes in the city. The results indicate that BEBs powered by South Africa’s coal-heavy Eskom grid (2022) exhibit higher CO2 emissions than diesel buses, with the grid’s 82.8% reliance on coal. Trickle charging BEBs amplifies emissions due to sustained grid use, while fast charging using photovoltaic (PV) solar systems mitigates emissions but involves energy demand challenges. Additionally, diesel buses are significant sources of NOx and SO2 emissions, contributing to air pollution, acid rain, and respiratory health concerns. BEBs charged on the Eskom grid indirectly emit notable SO2 and NOx due to coal combustion, contrasting sharply with PV solar-powered BEBs, which eliminate direct emissions and substantially reduce pollutants. Grid-connected PV systems with battery storage offer a balanced approach, decreasing reliance on coal-based electricity while maintaining operational reliability. The study concludes that transitioning Metrobus operations to PV-powered BEBs or hybrid grid-PV systems is recommended to reduce CO2, NOx, and SO2 emissions, achieving greater sustainability and mitigating environmental and health impacts.