Author(s)

Marco Schiavon, Luca Adami & Marco Ragazzi

Abstract

The transition towards electric mobility is expected to reduce the direct emissions of local pollutants and greenhouse gases (GHGs) from road transport. However, the environmental sustainability of road traffic is also influenced by the level of sustainability of the sources that compose the grid mix used to charge electric vehicles. The present paper aims at understanding if electric mobility can improve air quality and reduce the emissions of global and local air pollutants even if this transition is not supported by a continuous increase in the share of renewable sources in the grid mix. To answer this research question, two scenarios were evaluated through the application of emission and dispersion modelling: (1) a present-case scenario characterized by the movement of vehicles whose composition matches the latest statistics on the Italian vehicle fleet and (2) a future-case scenario entirely composed of battery electric vehicles (BEVs). Both scenarios considered the same study area: a portion of an Italian urban area characterized by the presence of a canyon-like street. To take the comparison to extremes, the few BEVs in the present-case scenario were assumed as fed by renewable energy, while a nearby coal power plant was considered as the power source for the future-case BEVs. In spite of its deplorable energy source (coal) for BEVs, the future-case scenario would allow saving 12% GHG emissions with respect to the present-case scenario. The maximum annual mean concentrations of nitrogen oxides and total suspended particles in the future-case scenario were 99.9% and 68.0% lower in the street canyon compared to the present-case scenario. However, depending on the power plant considered, additional pollutants may be emitted, which may worsen the local air quality, especially if the location, the size and the characteristics of the emission source are not adequately evaluated.

Keywords

air pollution, air quality, AUSTAL2000, carbon balance, dispersion modelling, emissions, environmental sustainability, road traffic, sustainable mobility, urban street canyon.