Abstract
Kyoto City was taken as an example of a domestic urban area in order to estimate the actual amount of food and paper biomass found in municipal solid waste. The annual amounts of food and paper waste were measured at 222 kt-wet and 223 kt-wet, respectively. At present, most of this is processed through incineration. After evaluation of the greenhouse gas (GHG) reduction effect and energy recovery ratio of the utilization system for this biomass, a biogasification (high-temperature and dry-type methane fermentation) system with gas engine (GE) power generation was found to be more beneficial than the existing system, which uses direct combustion with steam power generation and direct combustion with composting. In addition, biogasification with hydrolysis is expected to give a 27% improvement in GHG reduction effect and energy recovery ratio over the present system of combined biogasification with hyperthermal
(80 °C) hydrolysis technology operated by exhaust heat from a GE power plant. Futhermore, the use of biogas in fuel cells can reduce GHG emissions by up to 1.7 times compared to GE use. Diffusion of energy conversion technology with high efficiency is therefore being recommended for the reduction of GHG in Japan.
