Comparison of energy recovery system from municipal solid waste in terms of energy balance and life cycle CO_2 emission

摘要

We evaluated four systems for recovering energy from municipal solid waste in terms of life cycle energy and CO2 emissions. Two of these were a type of mechanical biological treatment, including a combined system of anaerobic digestion (AD) and incineration after mechanical separation, and bio-drying followed by mechanical separation for recovering solid recovered fuel (SRF). The other two systems were incineration with high rate power generation and refuse-derived fuel (RDF) recovery by a mechanical drying process. We compared the systems based on the data collected from Asahikawa City. Process flow and parameters for operation and utility consumption in the four systems were adopted from the literature. The bio-drying system showed the highest energy efficiency. It reduced the fuel material's energy content, but improved energy efficiency due to lower electricity and fuel consumption. The RDF production system recovered the highest energy by huge evaporation, but considerable fuel consumption resulted in the lowest energy efficiency. The combined system showed a higher energy recovery than incineration, but AD was less energy efficient due to the electricity consumption. Lifecycle CO2 emissions are closely related to energy balance. Among the various parameters, power generation efficiency and electricity consumption were highly sensitive to energy balance.