Evaluation of food metabolism in Chinese cities: based on emergy analysis

The rapid urbanization of the world requires attention to food metabolism processes at the micro-level of urban elements and exploration of the fundamental role of urban material and energy metabolism as represented by food metabolism. This study aimed to investigate the structure and intensity of urban food metabolism in 30 Chinese provinces using Emergy analysis and analyze the eco-efficiency of this metabolism. The findings are as follows: From 2000 to 2020, the annual growth rate of food metabolism flux in Chinese cities was 7.04%. In the "well-off society", urban residents have shown a preference for consuming high nutritional food such as meat, eggs and milk, which has become an important indicator of a high-quality lifestyle. However, this has led to an increase in the density and intensity of food metabolism, the density is mainly concentrated within the range of [0,5.0E + 08] sej/m 2 , with an average value of 2.4 E + 08 Sej/m 2 . The intensity of food metabolism can be categorized into three types, continuous expansion, lifting before lowering, and stable development according to the changing trends. The imbalance of regional density and intensity can be adjusted by changing the scale, type and structure of food circulation. Furthermore, the rapid food metabolism system has concealed ecological damage, environmental pollution, soil fertility decline and other problems. Although the eco-efficiency of food metabolism of Chinese urban residents has increased by 5.6%, they still face significant challenges in the utilization of non-renewable resources.