A study on Japan's energy demand and supply to achieve 80% reduction of CO₂ emission in 2050

Against the Government's policy to achieve 80% reduction of GHG in 2050 by utilizing new technologies including CCUS, we analyze the energy demand and supply balance to achieve 80% reduction of CO₂ emission in 2050 with existing zero emission technologies including renewables and nuclear power. Also, we clarify the options which achieve 80% reduction of CO₂ emission if nuclear power generation capacity is constrained. Assuming output of renewables never curtailed by installing batteries on a massive scale, generation capacity of nuclear power plants has to reach 29GW to achieve 80% reduction of CO₂ emission while maintaining network stability. 29GW of the nuclear generation capacity means some new nuclear power units should be constructed by 2050 even if capacity factor is assumed to be as high as 86.7%. Japan does not have much time left to decide on the use of nuclear power. With the service life of nuclear power plants at 60 years, the fleet will start to shrink drastically beyond 2050. Thus, further measures should be taken to limit CO₂ emission onward. Other options to achieve 80% reduction of CO₂ emission when capacity of nuclear power remains 16.8GW in 2050 are that CCUS of 30Mt-CO₂ is required, or economic growth rate has to fall to zero. Since power generated by renewables are already fully exploited, if 'methanation' is to be used on a large scale, import of hydrogen or additional zero-emission power supply is indispensable. If CCUS costs put additional burden on Japanese manufacturing industries, it may impair their international competitiveness. (author)