In response to the expected increase in power demand, we obtained the prediction that power supply is possible without a significant cost increase by spreading the use of solar power generation and wind power generation, which have large time fluctuations, and by adopting a power supply configuration that incorporates a power storage system for stabilization. In addition, the "Outlook for Energy Supply and Demand in 2030" of the 6th Strategic Energy Plan presented by the Agency for Natural Resources and Energy in October 2021 was evaluated by incorporating the parameters related to the power supply configuration and power source technology into the LCS multi-region optimal power generation model. By incorporating a power storage system into the power source composition plan proposed by the government and making it possible to relax inertial force constraints, we obtained the prediction of being able to meet not only the expected power demand but also larger demand and lower the dependence on nuclear power and the cost of power generation.