This paper describes the outline of integrated energy economic model and calculated result concerning Japan’s energy demand and supply outlook and carbon dioxide emissions to 2050. The energy model developed in this paper is integrated one which consistently combines econometric model endogenously generating various socio-economic factors and bottom-up type technology model, MARKAL, identifying cost-minimizing optimal mix of various energy technologies. Employing this model, Japan’s long-term energy outlook is evaluated under the scenario on both carbon regulation and nuclear power generation. In no carbon regulation scenario, CO2 emission in 2050 will be mitigated by approximately 40% from the level of emissions in 2005, if nuclear power plants will be constructed according to governmental electricity supply plan. Sluggish growth in nuclear power plant, however, would alternatively increase carbon-intensive coal-fired power plant which eventually boosts CO2 emissions. In carbon regulation scenario, imposing emissions cap of 60% reduction by 2050 from the emissions in 2005, renewable energy are expected to expand its portion in power generation mix, and the role of natural gas-fired power plant equipped with CCS would further expand if the deployment of nuclear power plant becomes stagnated.
