Eco-efficiency evaluation of urban complex ecosystem based on emergy and data envelopment analyses

Eco-efficiency is an effective tool to quantitatively analyze the input and output relation of social, environmental and economic perspectives of one ecosystem. It plays a key role to evaluate the sustainable development level of an urban ecosystem. By combining emergy analysis and data envelopment analysis (DEA) methods, this study proposes innovative emergy-based indicators and one new DEA-based model to measure the overall eco-efficiency of one urban ecosystem by employing a case study on Shenyang. Both emergy flows and eco-efficiency were calculated in order to assess the sustainable development levels from regional resources, environment, and economy perspectives. The results show that during the period of 2000 to 2010, the eco-efficiency of Shenyang had gradually increased. Emergy yield ratio first dropped a little bit, and then increased steadily. Environmental loading ratio rose significantly, showing an increasing resource pressure on Shenyang during its growth period. In order to improve its sustainable development, local governments should raise several appropriate policies, including optimizing energy-use structure, improving non-renewable resource use efficiency, and promoting waste recycling.