CO2 Emission Reduction and Primary Energy Conservation Effects of Cogeneration System in Commercial and Residential Sectors Considering Long-Term Power Generation Mix in Japan

Abstract

This paper proposes a comprehensive model to examine future CO2 emission reduction and primary energy conservation through the installation of a cogeneration system (CGS) in commercial and residential sectors of Japan considering its long-term power generation mix. With the development of a CGS model and a long-term generation mix model on cost minimizing basis, Japan’s prospective power generation structure is figured out and the potential of CO2 emission reduction and primary energy conservation by a CGS is evaluated. With considerable uncertainty remaining concerning various assumptions made for the model analysis, following results are identified. (1) In all fuel price scenarios in power plants, the installation of CGS in commercial and residential sectors accomplishes the reduction of primary energy consumption. (2) In a standard fuel price scenario, the installation of CGS in commercial and residential sectors achieves the reduction of CO2 emission. In a low fuel price scenario which is the case current fuel prices continue for the future, however, CO2 reduction effect becomes decreasing compared to the standard fuel price scenario because of the dominant generation share of a LNG fired plant and a LNG combined cycle in future generation mix and these less carbon intensive plants replaced by CGS. In the case where nuclear power plant becomes competitive and increases its share in future generation mix, CO2 emission from energy system conversely increases by installing CGS in comparison with before installing, because electric power generation of CGS gradually replaces a nuclear power plant. These results suggest that the CO2 reduction potential by CGS introduction is cautiously evaluated taking into consideration the future power plant construction program in Japan.