Mass, energy, and emergy analysis of the metabolism of Macao
Urban metabolism analysis has become an important tool for the study of urban ecosystems. The metabolism of a city can be seen as the processes by which the city transforms the materials and energy it requires to sustain its socioeconomic activity. In the present study, we analyzed the anabolic and catabolic flows that occur during Macao's urbanization processes. Macao is a tourist city with a dense population, but is short on natural resources; thus, most of its life-support services depend on resource imports from outside its system. We used mass, energy, and emergy analysis to quantify the metabolic processes that occurred in Macao in 2013. Macao's anabolic and catabolic density both increased to high levels due to a tremendous influx of visitors in 2013. By employing systems ecology based on mass, energy, and emergy metrics, we were able to quantitatively describe the city's resource metabolism. We found that by relying on a large amount of inflows to support anabolism compared with catabolic flows, Macao was able to absorb large amounts of negative-entropy materials, and that these flows of resources supported both its survival and its booming development. We also found tremendously high heat dissipation, and that after accounting for catabolism, the city retained less than 10% of the total input for anabolism.