Carbon footprint of battery electric vehicles considering average and marginal electricity mix

The current investigation presents a methodology to quantify the error in the greenhouse gas emissions of different electric passenger vehicles when considering the marginal instead of the average CO2 emissions. Both well-to-wheel and life-cycle assessment were carried out. The energy required for the vehicles was calculated by analyzing passenger cars of different segments and different powertrain systems in various driving cycles using detailed vehicle models. Results obtained were compared to the targets set by the European Union, following the current legislation, to highlight a realistic position of the different powertrains (electric, hybrid and combustion engines) in the current paradigm of the transport sector. The approach followed along the study showed variations respecting many previous works, unveiling higher environmental impact - in terms of CO2 - due to electric vehicles usage, although still below the pollution level of internal combustion engine cars, in the case analyzed. In normal conditions, pollution calculated based on marginal emissions turn to be more than the double in the current scenario for the case studied. The standpoint and methodology presented in the present work demonstrate that using average emissions values of the energy generation systems might lead to gross miscalculation of the environmental impact of the future transport sector.