Hybrid life-cycle assessment (LCA) of CO2 emission with management alternatives for household food wastes in Japan

In this study, we conducted a hybrid life-cycle assessment (LCA) to evaluate reductions in CO₂ emissions by food waste biogasification of household food wastes in Japan. Two alternative scenarios were examined. In one alternative (Ref), all combustible municipal solid wastes (MSWs), including food waste, are incinerated. In the other (Bio), food waste is biogasified, while the other combustible wastes are incinerated. An inventory analysis of energy and material flow in the MSW management system was conducted. Subsequently, the inventory data were summarized into an input—output format, and a make-use input—output framework was applied. Furthermore, a production equilibrium model was established using a matrix representing the input— output relationship of energy and materials among the processes and sectors. Several levels of power generation efficiency from incineration were applied as a sensitivity analysis. The hybrid LCA indicated that the difference between the Bio and Ref scenarios, from the perspective of CO ₂ emissions, is relatively small. However, a 13—14% reduction of CO₂ emissions of the total waste management sector in Japan may be achieved by improving the efficiency of power generation from incineration from 10% to 25%.