Search

Abstract A stable and reliable urban energy supply is essential for supporting sustainable regional and even national development. Further, a general definition and method is necessary to comprehensively evaluate urban energy supply security for different energy resources, identify key problems, and conduct regulations. Therefore, ecological network analysis (ENA) is introduced as a general systematic analysis tool to simulate and assess urban energy supply security, based on the idea that various components related to energy supply exist and interact in a common network. The proposed ENA model was used to evaluate and compare the security of coal, crude oil, and natural gas supplies for Beijing during 1997–2012. The evaluation included overall sustainability assessment, system property analysis, and structure analysis of energy supply systems. The results showed that the coal supply had the highest level of supply security, followed by the crude oil supply and then the natural gas supply. In addition, the crude oil supply system showed the most competitiveness in terms of the energy supply systems' properties. Scenario analysis yielded suggestions for improving urban energy supply security by maintaining energy production, increasing energy consumption within a certain range, strengthening and diversifying supply sources, and increasing strategic energy reserves. The ENA-based general model provides a useful tool for systematic evaluation of urban energy security from the supply perspective to quantitatively support urban energy management. Highlights • Ecological network analysis is applied to evaluate urban energy supply security. • A general network model of urban energy supply systems is established. • The supply security of coal, crude oil, and natural gas in Beijing are evaluated. • Different energy supply systems are compared via structure and property analysis. • Suggestions based on scenario analysis are given to improve energy supply security. [ABSTRACT FROM AUTHOR]

Highlights: [•] We developed an ecological network model for an urban system. [•] We studied Beijing's ecological hierarchy using ecological network analysis. [•] The hierarchy's layout was determined by means of utility analysis. [•] The top (consumer) level of the hierarchy exerts too much pressure on lower levels. [•] The recycling sector must improve its capacity to better support the system. [Copyright &y& Elsevier]

Based on urban metabolism theory, urban energy consumption and carbon emission can be analyzed and the urban energy structure and carbon metabolic processes can be specified. By combining input–output analysis with ecological network analysis, the embodied energy and carbon footprint implied in urban products and services can be quantified. On this basis, we introduced energy structure indices based on the embodied energy per unit carbon emitted (i.e., the emission efficiency), which we used to evaluate the energy structure attributes of the metabolic actors. This approach provides a scientific basis for energy conservation and carbon emission reduction. Beijing is trying to control pollution (especially the smog produced by coal combustion), and this task is complicated by its large metabolic fluxes and strong metabolic influence. In this study, we analyzed the energy consumption structure of 28 sectors in Beijing from the perspective of their carbon footprint, and divided the sectors into four categories based on the relationship between their embodied energy consumption and the emission efficiency. We found that most sectors had high energy consumption and low emission efficiency, and that from 2000 to 2010, Beijing's overall consumption structure alternated between high and low embodied energy per unit of carbon emission, but the overall trend of emission efficiency changed toward higher. The insights provided by our analysis reveal ways to reduce carbon emission. Based on the carbon footprints of the 28 sectors, we propose how managers could adjust its energy consumption structure to decrease energy consumption and carbon emission. [ABSTRACT FROM AUTHOR]

Abstract: If cities are considered as “superorganisms”, then disorders of their metabolic processes cause something analogous to an “urban disease”. It is therefore helpful to identify the causes of such disorders by analyzing the inner mechanisms that control urban metabolic processes. Combining input–output analysis with ecological network analysis lets researchers study the functional relationships and hierarchy of the urban metabolic processes, thereby providing direct support for the analysis of urban disease. In this paper, using Beijing as an example, we develop a model of an urban metabolic system that accounts for the intensity of the embodied ecological elements using monetary input–output tables from 1997, 2000, 2002, 2005, and 2007, and use this data to compile the corresponding physical input–output tables. This approach described the various flows of ecological elements through urban metabolic processes and let us build an ecological network model with 32 components. Then, using two methods from ecological network analysis (flow analysis and utility analysis), we quantitatively analyzed the physical input–output relationships among urban components, determined the ecological hierarchy of the components of the metabolic system, and determined the distribution of advantage-dominated and disadvantage-dominated relationships, thereby providing scientific support to guide restructuring of the urban metabolic system in an effort to prevent or cure urban “diseases”. [Copyright &y& Elsevier]

Along with rapid urbanization and economic development, urban household consumption has experienced a remarkable change, leading to a corresponding increase in direct and indirect carbon emissions. A systematic accounting of household carbon footprints (HCFs) in Beijing during 2002, 2007, and 2012 using a nested input-output model is presented in this paper. The results indicate that the per capita carbon footprint from urban household consumption in Beijing increased from 3054.05 kg in 2002–4611.12 kg in 2012, of which the indirect emissions were the majority. In terms of consumption structure, food, housing, transportation and communication, and education and entertainment were the four dominant sources contributing to the indirect urban HCFs in Beijing. With respect to the source, local Beijing was the largest contributor for itself materials and service provisions in 2002 and 2007, while the domestic source became the largest contributor in 2012, accounting for 55.08% of the total indirect household carbon emissions. Moreover, we also discovered that families with high income level had much higher HCFs compared to those with low income level. Given these considerations, transitions towards low-carbon household consumption are needed so as to provide equality and sustainability. • Nested input-output model is adopted to calculate household carbon footprints (HCFs). • Per capita HCFs in Beijing increased from 3054.05 kg in 2002–4611.12 kg in 2012. • Indirect emission constituted the majority of HCFs, accounting for 63.69% in 2012. • Income level has great impacts on HCFs due to energy intensive consumption pattern. [ABSTRACT FROM AUTHOR]