Climate change adaptation and mitigation potential of EVs in Tokyo metropolitan area

Penetration of low heat-emitting electric vehicles (EVs) in urban areas is expected to have a positive effect on climate change adaptation by improving the thermal environment, and indirect mitigation by reducing building CO2 emissions. To assess these effects, a case study was conducted in Tokyo using an urban canopy model. We quantified the impact and characterize its spatio-temporal structure, through a comparative evaluation with other forms of e-mobility (hybrid electric vehicles and fuel cell vehicles) and established UHI measures (ground greening and cool roofs). EVs showed the largest effect among all e-mobilities, both in absolute temperature reduction (Delta T) and cooling efficiency (Delta T per reduced heat), owing to the positive feedback on atmospheric stability. The Delta T caused by EV is more pronounced in the morning and evening hours, and in urban centers. On the other hand, the Delta T due to UHI measures peaks at midday and is more pronounced in suburban areas. In other words, they complement each other spatially and temporally. The peak Delta T caused by the EVs exceeded that of the UHI measures by approximately 40% of the total area. The contribution of indirect CO2 mitigation is negligible in the life-cycle CO2 emissions of EVs.