, Fujii M.
, Tasaki T.Name of Society :
3rd Annual IIES Scientific Workshop (2017)Name of Proceedings :
Cities are responsible for more than 60 percent of global energy consumption and three-fourth of world greenhouse gas emissions. Industrial and urban symbiosis can be an effective solution for resource recycling and energy conservation. Numerous studies have verified greenhouse gas emission reduction and economic benefits of industrial and urban symbiosis. However, few research focus on energy exchange between waste management system and urban energy system and efficient cascade use of energy from waste. In this study, we proposed and assessed an urban symbiosis network which integrates municipal solid waste treatment system, district heating system and industrial system. In the proposed symbiosis network, biomass such as food waste, sewage sludge are used to generate electricity, and the residues from the fermentation process are combusted in incinerators to minimize the amount of final disposal. Heat from incinerator is used for a district heating system in residential and commercial area nearby. The proposed symbiosis network improves the exergy efficiency through combined heat and power system, and cascade use of energy such as high pressure steam is supplied to industries, and low temperature hot water is used in district heating. Tokyo Metropolis were selected as a case. Energy flow analysis was applied in order to quantify energy saving benefits of the symbiosis network, and energy recovery efficiency was calculated. Environmental impacts such as CO2 emission reduction were evaluated by employing life cycle assessment. The results showed that the proposed urban symbiosis network and energy cascade use created significant energy saving benefits (up to 5.4% of the total energy consumption) at upstream fossil fuel production process and downstream waste disposal process. The system of urban symbiosis had a great potential of carbon reduction (up to 1.10 million ton), contributing not only to circular society, but also to urban energy system.