Study On Construction Of Ecological City Based On Material-energy Metabolism

Along with the increasing rate of urbanization in our country, the population living in cities are gradually growing.The population density is increased. In such a highly concentrated modern city, which is mainly directed by artificial built-environment, people are importing more and more resource from the nature, while exporting wastes which highly excess the load-capacity of the natural ecological system, leading to the environmental degradation in the surrounding area, resource depletion, degradation of natural ecosystem and imbalance of urban ecosystem metabolism. Based on the study of material and energy metabolism, through the analysis of the process and mechanism of material and energy metabolism, seek the ecological way of material and energy flow in city, provide the basis for the construction of ecological city.Based on the sufficient analysis and study of dynamic development about urban metabolism, material flow and energy flow together with the present situation of eco-city construction at home and abroad. According to Eurostat "material flow account and index-Guidelines" and international energy flow chart, Construct the flow analysis framework of material and energy flow; Put forward the evaluation index system and evaluation method in ecological of material and energy flow; Analysis material flow in2001-2010and energy flow in2011of Xi’an, Draw material flows overall view in2010and energy flow chart in201of Xi’an City; Conduct ecological evaluation of material flow from2001to2010and energy flow in2011of Xi’an; Finally discusses the approaches and Countermeasures of ecological construction of Xi’an. Specific research conclusions include the following:(1) Analysis of Urban Material Flow. Material flow in Xi’an from2001to2010are analyzed. Material flow structure in city scale and calculation indicators are established and modified to get adaptive to the situation in Xi’an. The material flow in Xi’an are analyzed from seven respects, namely quantity of imported resources, quantity of pollutants, intensity of material consumption, intensity of discharged pollutants, material productivity, resource efficiency and environmental efficiency, which contributed to the drawing of panoramic picture showing material flow in Xi’an. It is indicated that the industrial structure needs further adjustment to meet the requirements for the construction of ecological city.(2) Analysis of Urban Energy Flow. Based on the analysis of energy flow diagram, energy data in Xi’an from2001to2010are collected, analyzed, calculated and studied, resulting in the drawing of energy balance table and energy flow diagram for Xi’an. At the same time, the present situation of energy utilization in Xi’an is analyzed through energy flow diagram, which implies the first four end-consumers of energy, including industry, Commercial energy use and transportation, as well as low energy utilization efficiency. Suggestions, related to urban planning, are made to resolve these problems and thus new referable methods can be proposed for the construction of eco-city in Xi’an from the perspective of energy flow.(3) The Study about Material Ecologicalization in City. According to the theory of "population-society-economy compound ecological system" and the model of" pressure-state-response", based on the composition and characteristics of material flow, the indicator-system for assessing ecologicolization of urban materials are proposed in accordance with the scheme of material ecologicalization scheme. Moreover, an integrative indicator-system for ecological construction of urban material flow is built up by applying group analytical hierarchy process. The situation of material-flow ecologicalization in Xi’an from2001to2010is evaluated in this paper. In addition, methods and approaches for the construction of eco-city, regarding to biomass, metal minerals, industrial minerals, architectural materials, pollutants etc, are raised(4) The Study about Energy Ecologicalization In City. Through the analysis of energy flow diagram in Xi’an, Established city energy supply, energy processing and conversion, the terminal consumer sector and Energy End-use efficiency is two level evaluation index system. After giving comprehensive score to the ecological construction in Xi’an from the perspective of energy flow, the conclusion, that Xi’an is on the late stage of ecological construction from the energy flow perspective, is reached. There are several problems existing in the present situation of energy flow process in Xi’an:the energy structure is unreasonable, the utilization rate of sustainable energy is low, the energy consumption efficiency is disappointing, etc. Methods about modification for ecology of energy supply system, ecology of energy for heat and electricity supply, utilization of energy byproduct and cascade utilization of energy are all put forward in this paper.(5) The Study of Urban Space Ecologicalization Integrating Material flow and Energy Flow. In accordance with the principle of minimizing the inputs(resources) and output(waste), the circulation system of ecological environment in city is proposed. From the perspective of energy flow, it is suggested that, during the process of ecological construction in Xi’an, urban transportation system should be perfected; land use pattern should be optimized; spatial landscape structure should be consummated; the redundant air and heat should be recycled and reused together with the reclaimed water; and energy-efficient building should be highly developed. From the perspective of material flow, comprehensive utilization of solid waste, ecologicalization of industry cluster, reduction the waste of material and energy during the producing process are proposed. The ethical and moral concept about the harmony between human and nature can be reach by altering the traditional view from ideological perspective.