Integrated Environmental Assessment of Supply-Side and Demand-Side Measures for Carbon Dioxide Mitigation in Tokyo, Japan

Building on previously introduced concepts and software, we constructed an interlinked system of models, called an integrated model project, for assessing integrated effects of supply-side and demand-side technologies and policies for carbon dioxide (CO2) mitigation in urban areas. We used the integrated model project to evaluate scenarios that included introduction of a solid oxide fuel cell combined with a gas turbine topping cycle (SOFC/GT) as a supply-side technology and reduction of electricity demand by energy conservation and rooftop photovoltaic (PV) cells in residential and commercial buildings as a demand-side measure in Tokyo, Japan. Modeling results indicate that integrating multiple supply-side and demand-side countermeasures can result in more effective mitigation of CO2 emissions. In particular, although separately a moderate CO2 tax and the SOFC/GT technology do not produce large CO2 mitigation, the combination of the two with PV installation could result in a 50% reduction in CO2 emissions in 2050. Cancellation effects of combinations of supply-side and demand-side measures were also seen between supply-side SOFC/GT systems and demand-side rooftop PV cells, effects that might not be apparent without the integrated environmental assessment approach that we have adopted. An integrated environmental assessment approach using tools such as those described in this article could help researchers to assess these kinds of dynamic, nonlinear effects, which would not be predicted by conventional linear, additive approaches.