A study on the impact of collaboration between power systems and electric vehicles on the costs and CO2 emissions of energy system

The Japanese government has set a goal of achieving a decarbonized society by 2050, and decarbonizing the power system is one of the important issues. However, as the introduction of Variable Renewable Energies (VRE) increases, systems to absorb fluctuations in power generation will be required, which could significantly increase the cost of the overall energy system. On the other hand, the Electric Vehicles (EVs) are expected to be widely used in the future, and the usage of unutilized CO2-free power to charge EVs or the power supply from EVs to the power grid (Vehicle to Grid (V2G)) may help to mitigate fluctuations. Therefore, this thesis paper examined how much costs and CO2 emissions can be reduced in Japan's overall energy system by mitigating power system fluctuations through the collaboration between power systems and EVs. First of all, we hypothesized that the impact of the shift from combustion engine vehicles to EVs (EV shift) on costs and CO2 emissions may vary depending on how the electricity is generated, but we found that “EV shift” may reduce costs and CO2 emissions whether LNG or hydrogen is used as fuel for thermal power. In addition, our hypothesis was that the impact of EV introduction on the reduction of costs and CO2 emissions may vary by region, and we found that the impact is particularly large in regions with low power demand and high VRE potential. Furthermore, we hypothesized that a cooperative V2G charger, which can control both charging and discharging period, may be the best way to reduce costs and CO2 emissions, but the results showed that this charger type may not be the most cost-effective in many cases. However, this trend may change if the charger unit costs decrease and the penetration ratio of renewable energy increases, so it would be important to determine the type of charger to be installed based on these factors.S.M