The environmental performance of current mass-produced passenger vehicles in Japan

Abstract

This study systematically analyzed life cycle CO₂ (LCCO₂) emissions of a comprehensive set of mass-produced 2,000 cc class sedan-type vehicles, using a hybrid life cycle inventory approach. Gasoline and diesel internal combustion engine vehicles (ICEVs), hybrid electric vehicle (HEV) as well as battery electric vehicle (BEV) and fuel cell vehicle (FCV) were investigated, considering (i) the current BEV market trends, (ii) Japan's energy mix (the average for 2012–2014), and (iii) the use of the HVAC system. The results show that the annual average increment of CO₂ emissions in use phase by HVAC system in Japan (assumed annual mean temperature of 15°C) was presumed to be evenly 9% regardless of vehicle types, although further detail analysis is required. The CO₂ emissions in use phase of BEV were higher than those of HEV and FCV (applied hydrogen produced by steam reforming of LPG (on-site)) due to thermal power dominant electricity generation mix in Japan in recent years. As a consequence of high CO₂ emissions from power supply and battery production, the LCCO₂ emissions of BEV equipped with 75 kWh battery were higher than those of HEV, FCV (on-site), and conventional ICEV (diesel). By reducing the battery capacity to 40 kWh or less, the LCCO₂ emissions of BEV become lower than those of ICEVs and FCV (on-site), making BEV a competitive alternative. However, it is difficult that BEV mitigates both LCCO₂ emissions and driver's range anxiety. In conclusion, HEV shows the competitive performance in terms of LCCO₂ emissions with long driving range in Japan.