Emergy analysis on urban metabolism by counties in Beijing

摘要

Beijing is an international metropolis, with rapid urbanization during the last 30 years. However, it faces the challenge of sustainability with limited natural resources. This paper attempts to incorporate emergy analysis on urban metabolism to investigate the sustainability of the entire Beijing at the county level. Based on the time-series climate data and socioeconomic data, we calculated the structure, intensities, environment pressures and output efficiency of the urban metabolic emergy system by counties between 2005 and 2014. The result shows that the metabolic emergy stores of Beijing, especially in Capital Function Core (CFC) area, had been increasing significantly during the study period, especially for the increasing imported and exported emergy accounting. The 16 districts of Beijing can be grouped into four types of functional areas in terms of the function in urban metabolism. The five parts of urban metabolic emergy system had obviously spatial difference by counties, and the renewable emergy in CFC area and Urban Function Development (UFD) zone was obviously lower than in City Development (CD) zone and Ecological Conservation Development (ECD) area. The non-renewable emergy and waste emergy in CFC area, UFD zone and CD zone were obviously higher than that in ECD area. The imported emergy and exported emergy were significantly higher in Dongcheng, Xicheng and Chaoyang district. Emergy use intensities of CFC area had been increasing with the rapid rise in imported emergy and exported emergy, resulting in the increasing environmental pressure. However, the district governments of CFC area are trying to enhance output efficiency and sustainability to reduce waste emergy. The indices of emergy yield rate (EYR) and emergy sustainable index (ESI) had been gradually decreasing and the region with the highest value of EYR and ESI, in decreasing order, are: ECD area, CD zone, UFD zone, and CFC area. The result indicates that CFC area is more fragile and depen