In the previous report, we have shown that CO₂ emissions from electric power systems can be reduced by 85%, at almost the same power cost as that incurred in the present (2013) by 2050 and evaluated the economic impact of technology development of low carbon electric power system. In this paper, we evaluated the technologies that contribute to the system stability of low carbon electric power systems including enhancement of the electricity grid and its economics. As a result, we showed pathways to reduce 80 to 100% of CO₂ emissions from electric power systems.
　When renewable energy is introduced on a large scale, system stabilization measures are necessary. There is a concern about the influence of decreasing inertial force when reducing the proportion of synchronous generators which are mainly based on thermal power. For this reason, as measures to contribute to system stability, we evaluated the installed capacity of storage battery systems, the enhancement of the electricity grid, and the technology of electrical inertia. Also, it is shown that the total annual expense difference is about 5 trillion yen in the case of reduction of CO₂ emissions by 90%, which is half of the ratio of synchronous generators with electric inertial force. It is important to develop technologies to reduce the proportion of synchronous generators and to stabilize the system. Particularly, in order to reduce CO₂ emissions by 90% or more, the supply constraint of electrical inertial force has a large influence on the power generation cost. It is necessary to develop new technologies for system stabilization. In this way, we evaluate the economic impact of technological development and evaluate important technical development issues. Furthermore, there are remaining research issues such as the future increase in electricity demand that creates further technical restrictions.