Efficiency Evaluation For Urban Industrial Metabolism Through The Methodologies Of Emergy Analysis And Dynamic Network Slacks-based Measure Model

With the rapid development of urbanization,economic construction activities in cities become more and more frequent.The resulting problems of environmental pollution,manland relationship and resource depletion problems continue to profoundly affect the sustainable promotion and development of cities.The contradiction between urban economic development and ecological environment protection is the most prominent among them.Therefore,how to balance the coordinated relationship among economic growth,resource investment and environmental protection has become an urgent issue for urban sustainable development.From a systemic perspective,urban metabolism is considered a sufficient and effective method,forming a continuous and interconnected unified process by considering the input,transformation,and output of substances and energy.This process not only describes the input-output of various elements in the urban development process in detail,but also reflects the excessive loss or retention of substances and energy within the system,leading to a certain degree of environmental problems.Therefore,based on the concept of urban metabolism,this paper attempts to clarify the internal structure of urban system metabolism and the metabolic relationship between specific economic sectors,and explore the balanced development relationship of various elements in the urban system.Measure the efficiency level of urban industrial metabolism,find out the key causes of low efficiency,and provide theoretical reference and practical basis for the sustainable development of urban construction.In this paper,an evaluation model of urban industrial metabolic efficiency is established,which combines emergy analysis and dynamic network slacks-based measure data envelopment analysis(SBM-DEA)model.First of all,based on the emergy analysis theory,the network structure of industrial metabolism in urban system and the input-output indicators among various economic sectors are combed and constructed.At the same time,each element in the system is converted into a quantized value of a unified unit through emergy analysis,which provides a feasibility for evaluating the state and position of different energy carriers.Secondly,the dynamic network SBM model is used to calculate the efficiency score level of each stage,period,system and overall.This can help to determine at which specific stage and period the evaluated decision-making unit(DMU)begins to gain or lose efficiency.In order to reflect the impact of environmental pollution on the future development of urban industries,industrial metabolic waste is innovatively considered as an undesirable carryover to consider its impact on industrial metabolic efficiency.Finally,based on the panel data from 2016 to 2020,18 first-tier cities in China are selected for empirical research.The calculation results provide updated and improved suggestions for improving the industrial metabolism efficiency of these cities,and help these cities in China better realize the sustainable development of urban construction.The calculation results show that the metabolic efficiency of the 18 first-tier cities in China is low,indicating that all the evaluated cities need to make some appropriate adjustments to improve their metabolic efficiency levels.There is a significant heterogeneity in efficiency levels among cities and production departments.The relative efficiency values of the 18 cities in the sub-stages of agriculture,industry & construction more reached effective levels,while the metabolic efficiency performance in the service sector was slightly weaker than the first two sub-stages.By comparing the four traditional first-tier cities with the new first-tier cities,it can also find that the efficiency scores and rankings of the traditional first-tier cities are significantly better than the performance of the new first-tier cities.It indicates that the development of the four traditional first-tier cities is relatively more sustainable.Finally,the study also found that there is an undeniable relationship between the performance of urban metabolic efficiency and the geographical location of the city.The performance of eastern coastal cities is significantly better than that of deep inland cities such as the west and northeast,while the performance of cities in the central region is generally at the middle level.Based on empirical analysis conclusions,a specific framework for updating and improving suggestions has been proposed for the specific situation of each city,in order to provide support for policy formulation and decision-making by relevant departments and further assist in the research of sustainable development in urban construction in China.