Abstract
To achieve a goal of CO2 emissions reduction by 2030, the installation of high-efficiency energy supply equipment is progressing in Japan. Thus, many researchers have analyzed replacing scenario of such equipment that maximizes the effect of installing it. For example, the effects of efficiency and cost of energy supply equipment on diffusion process were reported. However, sensitivity analysis of scale of demand is insufficient. The purpose of this study is to derive the optimal configuration of energy systems in a household of the various scale of demand for the minimization of annual CO2 emissions from 2016 to 2030. In addition, we analyze the effects of replacing year on CO2 emissions from 2016 to 2030. As a result, polymer electrolyte fuel cell (PEFC) is the optimal equipment reducing CO2 emissions in regardless of the demand scale when CO2 conversion factor of the electrical grid is 0.474 kg-CO2/kWh. So as the heat pump water heater (HPWH) is the optimal equipment reducing CO2 emissions regardless of the demand scale when CO2 conversion factor of the electrical grid is 0.370 kg-CO2/kWh. In addition, replacing gas boiler with HPWH and installation of photovoltaics can reduce approximately 60 % of CO2 emissions in 2030.
