Emergy analysis on classified diversion with centralized disposal for municipal solid wastes of high calorific value

The disposal of municipal solid waste (MSW) has become a crucial problem in relation to urbanization and urban economic development. The method of diversified classification coupled with centralized disposal can effectively augment the effects of reducing and recycling MSW. The campus waste of typical universities in Xi'an City (Shaanxi Province) was taken as representative of the incineration type MSW with a high calorific value. The input and output of energy flow were resolved relevant to three disposal systems, namely, landfill-biogas power generation, incineration power generation, and biomass co-firing power generation. According to the physical composition and calorific value data, energy analysis was applied to evaluate the three MSW disposal systems. The comparison was done according to the five basic energy indexes, namely, energy yield ratio (η_EYR), environmental loading ratio (η_ELR), energy investment ratio (η_EIR), renewable input ratio (η_RIR), and the energy sustainability index (η_ESI), from the perspective of energy utilization, based on environmental sustainability and economic competitiveness. The analysis results show that the power generation processes of incineration and biomass co-firing have significant advantages in terms of energy efficiency and environmental impact. An optimal strategy of classified diversion with centralized incineration for the MSW with a high calorific value has the advantages of improving the environmental and economic benefits of reducing MSW.