Integrated approach for best mix of technologies of reduction of carbon dioxide emission – Tokyo Half Project ( THP ) –

Whereas various kinds of efforts have been paid to reduce greenhouse gas from manufacturing sector, emission has been significantly increased in non-manufacturing sector such as transportation, residential, commercial and service sector. Such GHG increase is closely related with urban activity both in direct way and in indirect way. The contribution of this non-manufacturing sector to all CO2 emission is increasing in many of the developed countries which are facing the difficult requirement of its reduction agreed in FCCC COP-3. Various technologies have been developed to reduce CO2 emission from urban area. Such research and development activity encompasses various fields so that the evaluation of the implementation of these technologies into actual urban area is very hard. Because these technologies sometimes interact and even compete with each other, simple summation of individual effect of reduction of CO2 easily results in overestimation of the effects of technological option. There is need of developing the method of integrated evaluation of such technologies when they are implemented into urban area. This method will elucidate the interaction among various technological option in quantitative way and provide the best set of technologies to be implemented to actual urban area. This will help long-term policy decision for fulfillment of CO2 reduction target. Various technologies to reduce CO2 has been and are developed and evaluation of CO2 reduction achieved by individual technology is shown based on the experimental operation. However, its effect in the actual situation in urban area must be evaluated with taking into account of interaction and competition among technologies. In fact, such interactive influence has been neglected in the evaluation of technology because technology has not yet introduced intensively and because the evaluation of interactive effect is difficult. However, interactive effects must be evaluated if significant reduction in CO2 emission is aimed at. Feasibility of individual technology in actual urban area should be evaluated. For example, implementation of district heating/cooling system for CO2 reduction is limited because it requires certain density of heating/ cooling demand. Researchers in various fields have initiated a project named Tokyo Half Project (THP). Target of THP is to demonstrate the feasible set of technologies to reduce CO2 emission from Tokyo to half of its value in 1990. The project members are mainly from the University of Tokyo in collaboration with MIT (Massachusetts Institute of