Abstract
The information about energy efficiency of electric vehicles in comparison to petrol vehicles is useful and significant for decision making of consumers. In Japan, the travel distance per electricity (km/kWh) or petrol (km/liter) are commonly used as indexes of energy efficiency. In this study, the conversion coefficients between these 2 indexes were estimated, on the basis of tank-to-wheel, well-to-wheel, and greenhouse gas emission. For tank-to-wheel, 1km/kWh corresponded to 9.58km/liter, and 4.08 for well-to-wheel. From the catalogs of electric and hybrid vehicles, both were equivalent in well-to-wheel energy efficiency. The conversion coefficients on the basis of greenhouse gas emission were 7.14 in case of Tokyo and 7.18 for Tohoku. However, this would vary due to the change in the structure of energy source for electricity production, caused by the east-Japan earthquake. The changes in coefficients were also estimated from the forecast of energy source structure of power plants in the next summer. The revised estimation of the coefficients were 5.67 for Tokyo and 5.79 for Tohoku. Despite the damage of nuclear power plants by the earthquake and growing dependence of power plants on fossil fuel, electric vehicle had superiority from a viewpoint of greenhouse gas emission in comparison to petrol vehicles.
