Long-term CO2 emission reduction scenarios in Japan

Japan's long-term CO2 emission reduction scenarios are assessed with a computable general equilibrium model with recursive dynamics, which was modified in order to assess the effects of renewable energy supply. The period of assessment is from 2000 to 2050 and the increase of gross domestic product per capita was assumed to be 2% per year. The following scenarios in which the level of CO2 emissions in 2050 will be 30% of the level in 1990 or less are proposed: (1) if the renewable energy supply in 2050 is less than the actual potential, an energy intensity improvement of 2.6% per year will bring about a CO2 emission level of 81 MtC in 2050; (2) if the electricity from renewable energy in 2050 can be supplied to the physical potential, and instead of solar heat, 50% more biomass energy can be supplied than the physical potential, the CO2 emission level in 2050 will be 86MtC by achieving a 2.0% per year energy intensity improvement. When the above two scenarios are appropriately combined, the CO2 emission level in 2050 becomes 66 MtC. In addition to energy efficiency improvement and renewable energy supply, changes in economic activity such as lower material input and higher labor productivity are also important to achieve the above target.