CO2 Emission Reduction Effect of Cogeneration System in Commercial and Residential Sectors Considering Long-Term Power Generation Mix in Japan

Abstract

Cogeneration system (CGS) is expected to be installed increasingly into commercial and residential sectors in Japan, due to its high potential of energy conservation characteristics, resultant high economic performance and CO2 emission reduction effect through its recent research and development. This chapter proposes a comprehensive model to examine future CO2 emission reductions through the installation of cogeneration system (CGS) in commercial and residential sectors of Japan, considering its long-term power generation mix. With the development of the CGS model and long-term generation mix model on a cost minimizing basis, Japan's prospective power generation structure is figured out and CO2 emission reduction potential by CGS in Japan is evaluated. While considerable uncertainties remain regarding the various assumptions made for the model analysis, some results have been identified. In the standard fuel price scenario, the installation of CGS in commercial and residential sector accomplishes the reduction of both CO2 emission and primary energy consumption. In the low fuel price scenario, in which case the current fuel price continues into the future, the CO2 reduction effect decreases compared to the standard fuel scenario because of the dominant generation share of LNG-fired plant and LNG combined cycle in the future generation mix of Japan. In the case where nuclear power plant obtains economic advantage and increases its share in the future generation mix, CO2 emission from the energy system, conversely, increases by installing CGS (in comparison with prior to installing) as electric power generation of CGS gradually replaces the nuclear power plants. These results suggest that the effect of CO2 reduction potential by the introduction of CGS is cautiously evaluated, taking into account future power plant construction program in Japan.