Urban Energy Metabolism Using Ecological Network Analysis: Case Study of Four Chinese Cities

We develop an ecological network model for urban systems using throughflow and utility analyses. The model uses compartments based on five sectors (energy exploitation, energy transformation, industry, households, and recovery). The trophic levels include energy producers, primary consumers, secondary consumers, and decomposers. The goal is to understand the metabolic system’s network structure and the ecological relations (i.e., mutualism, competition, etc.). The structure is derived from the weight distribution in the flow matrix, and the relations from the utility matrix. Four Chinese cities are used as examples (Beijing, Shanghai, Tianjin, and Chongqing). All four cities analyzed show an inverted pyramid structure in that producers were lower in total flow than consumers, which is consistent with the idea of cities as metabolic consumers on the landscape, and opposite to that of ecological systems which are supported by a large amount of producer flows. Regarding the ecological relations, Beijing had the highest mutualism index, followed by Shanghai, Tianjin, and Chongqing. Analyzing the structure and functioning of the urban energy metabolic system revealed suggestions for optimizing its structure and adjusting relationships among compartments, demonstrating how ecological network analysis can be used in future urban system research.