In transport section, it is necessary to reduce amount of CO₂ emissions and Oil dependence. Bio fuels and Fuel Cell Vehicle (FCV), Electric Vehicle (EV) and Plug-in Hybrid Electric Vehicle (PHEV) are expected to reduce CO₂ emissions and Oil dependence. We focus on PHEV. PHEV can reduce total energy Consumptions because of its high efficiency and can run with both oil and electricity. Introduction of PHEV reduces oil consumptions, however it also increases electricity demands. Therefore we must evaluate PHEV's CO₂ reduction potential, not only in transport section but also in power grid section. To take into account of the distribution of the daily travel distance is also very important. All energy charged in the PHEV's battery cannot always be used. That influences the evaluation.
We formulate the total model that combines passenger car model and power utility grid model, and we also consider the distribution of the daily travel distance. With this model, we show the battery cost per kWh at which PHEV begins to be introduced and oil dependence in passenger car section is to be reduced to 80%. We also show PHEV's CO₂ reduction potentials and effects on the power supply system.