Scenario Analysis on Greenhouse Gas Emission for Waste-to-Energy Alternatives in Japan

This study focuses on G reenhouse G as (GHG) emissions and reductions of M unicipal S olid W aste (MSW) incineration. The authors aim to estimate the detailed composition of GHG emissions and reductions from the waste incineration facility and their influence factors using two Japanese databases on the operation of incinerators from Japan Ministry of the Environment (1,243 facilities) and Japan Waste Research Foundation (814 facilities). The databases cover detailed data on MSW amount and characteristics, specifications of the facility, annual utility consumption, and annual energy/material recovery. The authors analyze the correlations among them and develop predictive models for the detailed components of GHG emissions and reductions. Japan Ministry of the Environment intended to group small municipalities for replacing small-scale incinerators to large-scale W aste-to- E nergy (WtE) facilities with a higher energy recovery efficiency. Based on the abovementioned data and models, the authors estimate the expected effects of the block formation and major technological alternatives for GHG mitigation by the national level. The current net GHG emission rate from 1,243 operating waste incineration plants in Japan in 2009 was estimated to be 653 kgCO 2 e/t. In the block formation, 1,007 plants were assumed to be closed; 236 kept operating; and 286 facilities would be newly built. Thenet GHG emission rate could be cut off to 454 kgCO 2 e/t by applying the block formation and technological alternatives with a higher energy recovery efficiency (stalker furnace with power generation by extraction condensing turbine providing steam higher than 3MPa and 300 C). Ash melting caused a larger GHG emission by the increase in energy consumption. The GHG reduction by slag recycling was limited. Furthermore, the net GHG emission ratecould be reduced to 242 kgCO 2 e/t by applying theBest Available Technique (BAT)for combined heat and power plants. When compared with the current status, BAT can reduce 185 kgCO 2 e/t by improving the power generation efficiency and 187 kgCO 2 e/t by expanding heat utilization. At present, heat utilization is very limited in Japan, but heat utilization should be more focused and promoted for GHG mitigation decisions.