As the center of human activities and social civilization, cities have developed at the cost of serious environmental degradation and huge eco-environmental pressure, which further lower human living standards and impede the sustainable development of urban ecosystems. Current urban dynamic methods have broader views and focus more on ecological aspects, e.g., the impact of emissions and resource consumption, but they lack a rigorous thermodynamic framework. Consequently, there is a need to modify existing processes and develop new technologies that minimize environmental impact while stimulating ecological flow. This paper describes the development of a forecasting model, named the emergy-based urban dynamic model, capable of accurately simulating the observed resource consumption, economic growth, and environmental impact of Beijing from 1999 to 2039. This model differs from previous urban emergy models by monitoring the negative effects to human well-being and ecosystem integrity in the developing urban system. A fresh perspective focuses on urban comprehensive performance, linking such impacts to a supply-side environmental cost evaluation (including ecological service supply, ecological and economic losses, and investment for treatment). In this introductory paper, we present the conceptual considerations of the most important components of the emergy-based urban dynamic model: the urban assets, lands, capitals, population, water resources, and economic and environmental loss. Each subsystem in this model will enrich the feedback dynamics, policy levers, and post-scenario analyses. Statistical information and calibration were also considered in this dynamic emergy accounting. The simulation revealed that water resources will be the most important limiting factor for the sustainable development of Beijing. A better approach would not be more engineering projects to deliver new supplies but to curb demand through efficiency improvements in water supply and consumption using the rule of law and economic incentives. The results of the simulation revealed that after the year 2015, many emergy indicators will collapse. The results of our study will enable urban policy planners to understand these inter-linkages by addressing specific damages to human health and the ecosystem's integrity, as well as by linking such impacts to a supply-side environmental cost evaluation. (C) 2013 Elsevier B.V. All rights reserved.
