Potential Impact of Battery Electric Vehicle Penetration and Changes in Upstream Process Emissions Assuming Night‐Charging on Summer O3 Concentrations in Japan.

A regional meteorology–chemistry model was used to evaluate the impact of battery electric vehicles (BEV) penetration on summer O3 concentrations in Kanto (Japan's most populous region). When all passenger cars shifted to BEVs, daytime ozone (O3) concentrations decreased over a wide area. The reduction of vehicle exhaust reduced O3 in inland suburban areas (NOx‐limited) and the reduction of gasoline fuel evaporation from vehicles and gas stations reduced O3 in urban areas (volatile organic compound (VOC)‐limited). The maximum location of maximum daily 8‐hr average O3 (MDA8hO3) sensitivity (−5%; −5 ppb) was at midway between urban and suburban areas, to which the reduction of exhaust and fuel evaporation contributed equally, respectively. The additional emissions from thermal power plants due to BEV's night‐charging could cause up to ±5% sensitivity to next‐day surface O3 concentrations topically. Depending on the O3 sensitivity regime (NOx‐ or VOC‐limited), additional NOx‐rich plumes from rural (urban) power plants tended to increase (decrease) the next day's O3. However, the spatial distribution of the regime varies temporally depending on such as NOx/VOC emission ratios and meteorological conditions. This study indicated that the distribution of negative (positive) O3 sensitivity by NOx‐rich plume is consistent with that of small (large) H2O2/HNO3 concentration ratios, indicating that H2O2/HNO3 works well as an indicator to discriminate O3 sensitivity regimes. Utilization of the H2O2/HNO3 indicator would enable regime distribution predictions without sensitivity simulations with varying NOx and VOC emissions, which would contribute to reducing computational costs. Plain Language Summary: Ozone (O3), which causes respiratory health effects, is formed in the atmosphere by its precursors NOx and volatile organic compound (VOC). Conventional gasoline vehicle exhaust is a major source of NOx and VOC, gasoline fuel VOC evaporate from vehicles and gas stations and thermal power plants emit mainly NOx. This study evaluated the impact of BEV penetration on summer O3 concentrations in Kanto using numerical simulation. When all passenger cars shifted to BEVs, daytime O3 concentrations decreased over a wide area in Kanto (up to −5%). The additional emissions from thermal power plants due to BEV night‐charging had a ±5% impact on next‐day O3 concentration topically. O3 has a NOx‐ or VOC‐sensitive region (called O3 sensitivity regime), and different effective NOx‐VOC emission measure. The above sensitivity was explained by the emission change by BEV shifting and the O3 sensitivity regime distribution. The spatial distribution of the regime varies temporally depending on NOx/VOC emission ratios and meteorological conditions. This study also indicated that H2O2/HNO3 is a useful indicator for its discrimination. Utilization of the H2O2/HNO3 indicator would enable regime distribution predictions without sensitivity simulations with varying NOx and VOC emissions, which is originally required, and would contribute to reducing computational costs. Key Points: The impact of battery electric vehicle (BEV) penetration on summer O3 concentrations in the Kanto region of Japan was evaluatedDaytime O3 decreased in both urban and inland suburban areasAdditional NOx emission from power plants due to night‐charging for BEV affected next day daytime O3 depending on meteorological conditions [ABSTRACT FROM AUTHOR]