Ecological accounting and evaluation of urban economy: Taking Beijing city as the case

Urban economy is confronted with increasing biophysical limitations derived from the exhaustion of natural resources and the depletion of environmental capacity, and human cultural diversity has been declining during the fast urbanization. The conventional anthropocentric economics, regarding the natural environment as the ‘exterior’ of human economy, is invalid in the scientific evaluation on the contribution of natural resources and environment as well as human culture when facing the current urban crises. The theory of embodied cosmic exergy, as the latest development of ecological economics and ecological thermodynamics, is introduced in this study to construct an ecological evaluation framework of urban economy. The advantage of embodied cosmic exergy dedicated to ecological economics has been discussed in comparison with other ecological evaluation alternatives. Transformities describing hierarchies and manifesting quality are systematically calculated and tabulated. A new framework of embodied cosmic exergy based on network accounting (EmexNA) is sketched out in this study, taking not only diversity flows but also ecological stocks into consideration. The stock based concept of ‘ecological wealth’ and the flow based concept of ‘ecological cost’ as well as related evaluation indicators are developed based on EmexNA. Taking Beijing city as the case, the network accounting and related ecological evaluation of a practical urban economy are carried out in this study in the light of the basic social, economic and environmental data available from 1990 to 2005 of Beijing. The system construction and the ecological mechanism of the development of Beijing economy are correspondingly illuminated and discussed.     

Scarcity of exergy and ecological evaluation based on embodied exergy

The driving force of the earth system is shown to be the cosmic exergy due to radiational difference between the sun and the cosmic background, instead of the solar energy. The scarcity of cosmic exergy availability as the fundamental natural resource for the ecosphere and the human society is revealed by a systematic study on the global consumption of the cosmic exergy in the earth and a budget of the exergy consumption with respect to main terrestrial processes. A conceptual framework or ecological evaluation is developed on the basis of a new concept referred to as embodied exergy in terms of the cosmic exergy consumed directly or indirectly in making or sustaining a general commodity as a product, service or an emission. As a generalization of Szargut’s cumulative exergy consumption in resource analysis, embodied exergy is chosen, in place of embodied energy, to define Odum’s emergy. Concrete calculation schemes for embodied exergy accounting are provided as a systematic revision and rephrasing of existing embodied emergy analysis.     

Resources use and greenhouse gas emissions in urban economy: Ecological input–output modeling for Beijing 2002

The embodiment of natural resources and greenhouse gas emissions for the urban economy of Beijing economy 2002 by a physical balance modeling is carried out based on an extension of the economic input–output table into an ecological one integrating the economy with its various environmental driving forces. Included resources and greenhouse gas emissions belong to six categories as energy resources in terms of primary energy and secondary energy; water resource; emissions of CO₂, CH₄, and N₂O; exergy in terms of energy sources, biological resources and minerals; and solar emergy and cosmic emergy in terms of climate resources, soil, energy sources, and minerals.     

Ecological evaluation of Beijing economy based on emergy indices

An integrated ecological evaluation of the Beijing economy was presented in the paper based on the emergy accounting with the data in 2004. Through calculating environmental and economic inputs within and outside the Beijing economy, this paper discusses the Beijing’s resource structure, economic situation and trade status based on a series of emergy indicators. Through the comparison of the systematic indicators of Beijing with those of the selected Chinese cities, the general status of the Beijing economy in China is identified. The results also show that most indicators of Beijing are located at middle levels among the selected Chinese cities. Particularly, the environmental impacts, expressed by the ratio of waste to the renewable emergy, and the ratio of waste to the total emergy use, are 84.2 and 0.26, respectively in Beijing in 2004, which indicate that the Beijing economy is greatly reliant on the imported intensive fuels, goods and services with high empower density and environmental loading.     

Emergy-based ecological account for the Chinese economy in 2004

This paper provides an integrated study on the ecological account for the Chinese economy in 2004 based on emergy synthesis theory. The detailed flows of the Chinese economy is diagramed, accounted and analyzed in categories using the biophysically based ecological accounting. Through calculating environmental and economic inputs within and outside the Chinese economy, this paper discusses the Chinese international exchange, describes the resource structure, and assesses its sustainability as a whole. Also, the comparison of systematic indicators, such as emergy/dollar ratio, environmental load ratio, and emergy self-support ratio, with those of the other countries is tabled and explored to illustrate the general status of the Chinese economy in the world. Take, for example, the environmental load ratio, which was 9.29 in China 2004, it reveals that the Chinese economy put high pressure on the local environment compared with those of the environment-benign countries, such as Brazil (0.75), Australia (0.86) and New Zealand (0.81). In addition, in this paper, the accounting method of tourism is adjusted based on the previous researches.     

Comparison of typical mega cities in China using emergy synthesis

An emergy-based comparison analysis is conducted for three typical mega cities in China, i.e., Beijing, Shanghai and Guangzhou, from 1990 to 2005 in four perspectives including emergy intensity, resource structure, environmental pressure and resource use efficiency. A new index of non-renewable emergy/money ratio is established to indicate the utilization efficiency of the non-renewable resources. The results show that for the three mega urban systems, Beijing, Shanghai and Guangzhou, the total emergy inputs were 3.76E+23, 3.54E+23, 2.52E+23 sej in 2005, of which 64.88%, 91.45% and 72.28% were imported from the outsides, respectively. As to the indicators of emergy intensity involving the total emergy use, emergy density and emergy use per cap, three cities exhibited similar overall increase trends with annual fluctuations from 1990 to 2005. Shanghai achieved the highest level of economic development and non-renewable resource use efficiency, and meanwhile, lower proportion of renewable resource use and higher environmental pressure compared to those of Beijing and Guangzhou. Guangzhou has long term sustainability considering an amount of local renewable resources used, per capita emergy used, energy consumption per unit GDP and the ratio of waste to renewable emergy. It can be concluded that different emergy-based evaluation results arise from different geographical locations, resources endowments, industrial structures and urban orientations of the concerned mega cities.     

Measurement and evaluation of the metabolic capacity of an urban ecosystem

Cities as superorganisms confront disturbances from their metabolic processes, including large metabolic fluxes, low stocks of resources and products, and a low efficiency of the urban material metabolism. Based on ecological thermodynamics, an indicator system is established in this paper to evaluate the fluxes, stocks, and effiency of the urban material metabolism using emergy analysis. Also, a new model for the urban material metabolism is proposed to define the production possibility curve using a wealth index (WI) and an ecological effiency index (EEI). Then, six large Chinese cities including Beijing, Shanghai, Tianjin, Chongqing, Guangzhou, and Shenzhen are selected as typical cases to validate the proposed model. The results show that Shenzhen has the highest metabolic capacity, followed by Beijing, Shanghai, Guangzhou, Tianjin, and Chongqing. It is also reflected that different urban material metabolisms of the six cities are resulted from the varied regional metabolic capacities, thus providing insights into how cities improve their metabolic capacities. Meanwhile, Shenzhen has the highest WI and EEI, Chongqing has the lowest WI and EEI, and Beijing, Shanghai, Tianjin, and Guangzhou has low WI and high EEI. It is also shown that the sustainable operation of the urban material metabolism reflects the mutualism and symbiosis between socioeconomic development and ecological environment protection.     

Emergy-based urban ecosystem health assessment: A case study of Baotou,China

Ecosystem health has been a hot topic of ecosystem management research for years. Considering the urban area as a complex ecosystem consisted of natural, societal and economic entities, urban ecosystem health assessment is necessary to be conducted for the scientific management and proper ecological restoration. Combining with the ecosystem service function of the urban ecosystem, theoretical framework and methodology of the urban ecosystem health assessment based on emergy are proposed and the temporal variation of the health level of the city are also outlined in this paper. Following the principle of ecosystem health assessment, four major factors, including vigor (V), organizational structure (O), resilience (R) and function maintenance (F), are integrated to construct a novel emergy-based urban ecosystem health index (EUEHI). Based on the EUEHI and comparing with those of five other typical Chinese cities, the case study of Baotou city shows that its urban ecosystem health level is steadily arising despite the year 2001 as a turning point. Due to the emphasis on the resource structure adjustment and utilization efficiency, Baotou has obtained a better organizational structure and service function for the total urban ecosystem.     

Emergy-based energy and material metabolism of the Yellow River basin

The Yellow River basin is an opening ecosystem exchanging energy and materials with the surrounding environment. Based on emergy as embodied solar energy, the social energy and materials metabolism of the Yellow River basin is aggregated into emergetic equivalent to assess the level of resource depletion, environmental impact and local sustainability. A set of emergy indices are also established to manifest the ecological status of the total river basin ecosystem.     

Exergy as a unified measure of water quality

The concept of exergy has been applied to ecological evaluation, resource accounting and environmental impact assessment. As a suitable indicator for ecological evaluation, exergy analysis presents a unified thermodynamic measure of objective evaluation of resources and environment with exergetic unit. A case study of water quality assessment using exergy analysis is presented. Compared with other existing methods, exergy accounting provides a unitary and objective measure for water pollution as a result of the application of the thermodynamic concept to water quality assessment.     

Emergy evaluations for constructed wetland and conventional wastewater treatments

Based on emergy synthesis, this study presents a comparative study on constructed wetland (CW) and conventional wastewater treatments with three representative cases in Beijing. Accounting the environmental and economic inputs and treated wastewater output based on emergy, different characteristics of two kinds of wastewater treatments are revealed. The results show that CWs are environment-benign, less energy-intensive despite the relatively low ecological waste removal efficiency (EWRE), and less cost in construction, operation and maintenance compared with the conventional wastewater treatment plants. In addition, manifested by the emergy analysis, the cyclic activated sludge system (CASS) has the merit of higher ecological waste elimination efficiency.     

Emergy-based analysis of Beijing–Tianjin–Tangshan region in China

An emergy-based analysis was conducted for the Beijing–Tianjin–Tangshan urban agglomeration district from perspectives of emergy density, resource structure, environmental pressure and resource use efficiency during the period of 1991–2005. The results showed that Beijing, Tianjin and Tangshan as contiguous regions shared similar characters and evolving trends in certain aspects as emergy intensity and proportion of local renewable resources on the whole. As for the local resources availability, process efficiency and environmental pressure, however, these three cities have significant differences. With comparison of the other cities in China, it is shown that Beijing–Tianjin–Tangshan region has higher environment loading and lower sustainability level though enjoying rapid urbanization process and economic development. This study also suggests that the first priority on economic development competition within urban agglomeration regions may lead to the wasting of resources and redundant construction, while cooperative and rational selection for development pattern are the proper choice for coordinate regional development and long term sustainability to overcome resource restrictions.     

Emergy analysis of a farm biogas project in China: A biophysical perspective of agricultural ecological engineering

This paper aims to present a biophysical understanding of the agricultural ecological engineering by emergy analysis for a farm biogas project in China as a representative case. Accounting for the resource inputs into and accumulation within the project, as well as the outputs to the social system, emergy analysis provides an empirical study in the biophysical dimension of the agricultural ecological engineering. Economic benefits and ecological economic benefits of the farm biogas project indicated by market value and emergy monetary value are discussed, respectively. Relative emergy-based indices such as renewability (R%), emergy yield ratio (EYR), environmental load ratio (ELR) and environmental sustainability index (ESI) are calculated to evaluate the environmental load and local sustainability of the concerned biogas project. The results show that the farm biogas project has more reliance on the local renewable resources input, less environmental pressure and higher sustainability compared with other typical agricultural systems. In addition, holistic evaluation and its policy implications for better operation and management of the biogas project are presented.     

New advances in economic modelling and evaluation of environmental issues

This paper gives an overview of recent progress made in modelling economic environmental systems and in environmental policy analysis. In the modelling part attention will be given to new integrating frameworks offered inter alia by materials balance approaches, especially in the context of linkages between physical environmental phenomena and economic production and valuation. These can be relevant for studying materials-product chains, multisectoral materials flows, or even multiple use of complex ecosystems. Modern approaches will be dealt with, such as analysis for sustainable development, and ways of incorporating scenario experiments in environmental modelling approaches. In the context of sustainable development, modelling of multiple use of ecosystems and of spatial dimensions is also discussed. In the last part of the paper new advances in the area of environmental policy analysis will be dealt with. The main focus will be on methods for addressing uncertainty in evaluating environmental policy strategies, in particular fuzzy information and the use of meta-analysis.     

Emergy as embodied energy based assessment for local sustainability of a constructed wetland in Beijing

Ecological treatment engineering has been widely accepted as an artificially designed work to deal with the deteriorating ecological environment with low energy and resource consumption. To measure the energy and resource consumption and environmental support contained in the constructed wetland as a kind of ecological treatment engineering, emergy as embodied solar energy based assessment is performed and relative emergy-based indices including emergy yield ratio (EYR), emergy load ratio (ELR), emergy sustainability index (ESI), net economic benefit index (Np), and renewable percentage index (Pr), are also modified to evaluate the local sustainability of the constructed wetland in this paper. A case study on Longdao River constructed wetland compared with those of some earlier conventional treatment systems indicate that more local renewable resources and less ecological cost are involved, thus promoting the economic benefit due to less energy and resource consumption and simultaneously lowering the environmental stress of the treatment system on the local areas.     

Exergy-based water resource allocation of the mainstream Yellow River

Based on the water resource exergy including chemical exergy, thermal exergy, potential exergy and sediment exergy, the allocation of water resource exergy along the mainstream Yellow River is illuminated. The water resource exergy for different anthropocentric water uses is also classified as agricultural irrigation exergy, industrial exergy, urban domestic exergy and rural domestic exergy. Aquatic exergetic ecotope (AEE) index is proposed as an indicator of the river ecosystem status in view of resource characteristic of exergetic assessment. Finally, the influences of the intake water on the AEE indices are well illustrated to reveal the possible impacts of water allocation on the river ecosystem status.     

Water resources in unified accounting for natural resources

The aim of this paper is to incorporate the water resources into the unified resources accounting based on scientific objectivity so as to present a brief portrait of the significance of water for the resource conversion and management of the national-scale society in a systems ecological perspective. The water resources in sustaining the human society are incorporated into the total exergy budget and national-scale social exergy accounting framework, not only by accounting the conventionally usable water flowing through society regarding seawater as reference environment, but also by introducing the evaporation exergy of freshwater as essential investment from the hydrological cycle. A case study of the Chinese society 2001–2005 is conducted, with the societal system broken down into seven sectors, i.e., extraction, conversion, agriculture, industry, transportation, tertiary and households sectors, to explore the resource utilization structure based on the proposed accounting method. Typical results for China 2005 showed that the total net input of the societal conventional resource exergy was 87.9 EJ, of which 75.4 EJ was from mineral resources and 22.6 EJ from other resources, while the water resource exergy input amounted to 105.1 EJ, which contributed 54.5% of the total resources exergy investment to the total society. Finally, the exergetic resource use intensities (RUIs) for six sectors were calculated, with the results that RUIs of agriculture and conversion sectors are much higher than those derived from conventional resource accounting.     

Carbon emissions and resources use by Chinese economy 2007: A 135-sector inventory and input–output embodiment

A 135-sector inventory and embodiment analysis for carbon emissions and resources use by Chinese economy 2007 is presented in this paper by an ecological input–output modeling based on the physical entry scheme. Included emissions and resources belong to six categories as: (1) greenhouse gas (GHG) in terms of CO₂, CH₄, and N₂O; (2) energy in terms of coal, crude oil, natural gas, hydropower, nuclear power, and firewood; (3) water in terms of freshwater; (4) exergy in terms of coal, crude oil, natural gas, grain, bean, tuber, cotton, peanut, rapeseed, sesame, jute, sugarcane, sugar beet, tobacco, silkworm feed, tea, fruits, vegetables, wood, bamboo, pulp, meat, egg, milk, wool, aquatic products, iron ore, copper ore, bauxite, lead ore, zinc ore, pyrite, phosphorite, gypsum, cement, nuclear fuel, and hydropower; (5) and (6) solar and cosmic emergies in terms of sunlight, wind power, deep earth heat, chemical power of rain, geopotential power of rain, chemical power of stream, geopotential power of stream, wave power, geothermal power, tide power, topsoil loss, coal, crude oil, natural gas, ferrous metal ore, non-ferrous metal ore, non-metal ore, cement, and nuclear fuel. Accounted based on the embodied intensities are carbon emissions and resources use embodied in the final use as rural consumption, urban consumption, government consumption, gross fixed capital formation, change in inventories, and export, as well as in the international trade balance. The resulted database is basic to environmental account of carbon emissions and resources use at various levels.     

Net ecosystem services value of wetland: Environmental economic account

For decision making in terms of environmental economics for wetland construction, restoration and preservation, net ecosystem services values of constructed, human-interfered and natural wetlands are explored in the present work as a comparative study. The ecosystem services values of a pilot constructed wetland in Beijing, China in different discount rates and time horizons are accounted and compared with those of the natural wetlands all over the world as a mean and of a typical human-interfered wetland in Wenzhou, China. Results show that in both finite and infinite time horizons considered, the constructed wetland has the largest net services value in a reasonable discount rate.     

Flow models for assessing human activities

The concept of flow is a fundamental one in describing human activities. This paper outlines recent modelling work which describes systems in terms of physical flows. The role of such models in assessing system changes is discussed using an extended case study from the field of natural resource analysis, and the complementary nature of environmental, economic and other bases of evaluation is considered.