In this proposal, we considered the stability of the electric grid system in Japan, and evaluated the generation costs for a scenario involving a high ratio of renewable energy, with close to zero CO₂ emissions. At the Center for Low Carbon Society Strategy (LCS), we have developed an optimal multi-region power generation model based on the system stability from this analysis. A method of technological evaluation based on the LCS’s manufacturing technology database was used for technological and economic evaluation of renewable energy in the future, from which the following results were obtained. By 2050, CO₂ emissions from electric power systems can be reduced by 85% at almost the same power cost as that incurred in the present (2013). In particular, photovoltaic (PV) power and battery systems will contribute to the establishment of cost-effective and low-carbon power generation systems. In scenarios with annual power consumption as high as 800 TWh, PVs accounting for more than 300 GW have been installed, generating over 30% of the total power consumption. The capacity of installed battery systems was taken to be 300-510 GWh (supplying 10%-30 % of the total power consumption). However, power costs sharply increased when CO₂ emissions were reduced by more than 90%. It will be possible, in technological terms, to achieve a zero-emission power generation system after 2050, but the generation costs will more than double. It will be necessary for us to consider measures such as development of hot dry rock geothermal power generation, reduction in power demand, rationalization of the grid system and hydrogen power generation. These results show that the methodologies in this proposal are effective for the quantitative evaluation of low-carbon power supply systems, taking system stability into account.