Evaluation of Ecological City Index in Chenaran City for Sustainable Development using Emergy

Document Type : مقاله پژوهشی


Ferdowsi University of Mashhad


1 Introduction
In this research, the ecological indicators and sustainable development dimensions in the city of Chenaran have been evaluated and the data analysis tool are the Emergy method. Indicators such as renewable, non-renewable, fuel and products have been used, and then Chenaran City has been examined in terms of different dimensions of Emergy (intensity, structure, efficiency and environmental pressure), which is used to examine the severity from Emergy's density and per capita, in Emergy's review of the structure, Emergy flows from renewable sources compared to energy and material imports, as well as self-sufficiency and process efficiency, Emergy fuel and electricity, and ultimately to show environmental pressure and Sustainability Indicators (ESIs) are used to combine all factors and currents that are EYR to ELR (Emergy Performance to Environment Load), as well as Capacity Capacity Tolerance Based on Renewable Emergy.
2 Materials and Methods
research method
This research is a Quantitative research. The information obtained from various sectors (ecological indicators) includes renewable resources (R), non-renewable resources (N), materials (G) and fuel (F), which are indicators presented by Odum. Using the Emergy method, it was measured and then analyzed and analyzed in four dimensions (Emergy intensity, structure, efficiency and environmental pressure) and its subcategories and related formulas.
Emergy calculation method
Calculating Emergy using the thermodynamic basis of all forms of energy, resources, and human services that converts them to the equivalent of a form of energy, usually Emergy Solar. To evaluate a system, and also to organize the assessment and account for all inputs and outputs, a table is to be drawn from all the assessment flows, including actual flows of resources, labor, and energy. And then the final step of the Emergy Assessment is an interpretation of quantitative results. In some cases, an assessment is conducted to determine the status (appropriate or inappropriate) of an environmental development plan, and sometimes evaluation may seek to make the best use of resources to maximize Be a curiosity. Emergy assessment is both quantitative and analytical. Emergy approach evaluates complex systems and ultimately analyzes public policy and environmental management issues (Silvert, 1982).
An Emergy flow defined by the current energy of a type that is used directly and indirectly in a service or product and its unit is Sej. As a result of the effective factors, the position variables and other system features can be converted to a normal metric unit, solar emergy. With the definition of Emergy Emk, the flow k obtained from a process is given below:
Emk = ∑iTriEi    , i= 1,2,….,n                                       (1)
Where Ei is the actual energy content of the independent flow of i into the process and the Tr, corresponding transformation (correspondence) of the input current i, which has already been estimated.
After the table is prepared for the evaluation of all inputs, the Emergy unit value of the product or process is calculated. The output, for the first unit of energy, is evaluated, and then the Emergy input and the energy unit value are calculated by dividing the Emergy by the output units. The unit values that yield the result for any evaluation are also useful for other Emergy evaluations. Therefore, Emergy evaluations generate the values of the new Emergy unit (Skibaba, 2010).
3 Results and Discussion
Chenaran city status assessment was carried out at the level of four main indicators (Emergy intensity, Emergy structure, Process efficiency and Environmental pressure). Each of the above is derived from the measurement of the sub-indicators calculated and analyzed by the Emergy method.The calculation and measurement of Emergy are shown in the following four dimensions:
Emergy Intensity
The total consumption of Emergy in the city of Chennan is 2.81e + 21 (sej) according to the calculations made in the study year. Emergy density and Emergy density were used to evaluate the severity of Emergy. Results were 3.81e + 15 and 5.75e + 16, respectively. Emergy density and capability play important roles in urban system operations.
Emergy structure
Emergy structure is critical to the sustainability of the area, given the rapid expansion of urbanization. Emergy is needed to maintain the observed structure of the two main sources of the natural environment and the use and import of fossil fuels and commodities from other economic organizations, and according to information obtained, Emergy flows from renewable sources compared to energy imports. And the material is relatively small. Although the city is not very extensive and industrial, it is a sign of the imbalance of currents in the urban system. The portion of renewable resources is 7.48e + 16, which is lower than non-renewable resources, indicating that living systems in the region are heavily dependent on non-renewable resources and, of course, the diversity of urban performance. It also cannot be ignored. Another indicator related to the Emergy structure is self-sufficiency ratio. According to the calculations carried out by Chenaran, self-sufficiency rate declines. Because high self-sufficiency level indicates good situation and low self-sufficiency level indicates adverse situation and Chenaran city with low self-sufficiency rate is 4.63e-3 or (0.046) and this fact indicates non-renewable and current resource flows. It also shows an increase in Emergy fuel coming into the city and less use of local resources. The use of fossil fuels has a major impact on the structure of Emergy and the city.
Process efficiency
Two indicators related to process efficiency are the use of Emergy fuel and electricity. To investigate the systematic functioning of the city. Fuel and electricity play a crucial role in urban development, and the intensity of these indicators can affect productivity. As the results show, the fuel and electricity used in the city of Chenaran are generally at a relatively high level, although the factories and industries in the city of Chenaran cannot be denied consumption of energy and consequently the use of fuels. And it has increased electricity in the city of Chennai and could cause problems in the future. And finally, based on the results of the calculations, it can be seen that the city during the process of industrialization and urbanization is seeking more productivity of resources and consequently their demands for resources also increase, thus causing damage to the Provides local resources and overuse of non-native and non-renewable resources.
Environmental pressure
To illustrate the environmental pressure in an ecosystem, it is important to discuss the pollution and overuse of non-renewable resources and the depletion of local and renewable resources. As mentioned earlier, the city of Chennaran has a high percentage of non-renewable resources and fossil fuels. It has intensified pollution and harmed the environment and ecosystem. The city's dependence on non-renewable resources and mass waste production adds to the environmental pressure. And, in fact, only fully and with respect to all different aspects of urban operations can we have a good overview and perspective of urban development with the concept of long-term sustainability.


It is important to pay attention to the principles of sustainable development, especially implementation and move towards becoming an ecological city. The results show that in four main indicators (Emergy intensity, Emergy structure, process efficiency and environmental pressure) Chenaran City Given that the situation is relatively stable in the present situation, but the orientation in the actions taken, it has been shown that activities in the environmental field were not in line with the idea of an ecological city and that fuel from material emergy flows. , Renewable and non-renewable resources, have been identified.
To represent the environmental pressure and sustainability indices (ESIs) in an urban ecosystem, a combination of all factors and streams is used, which is the EYR to ELR ratio (Emergy function to environmental loading), according to the information obtained, The ELR indicates an imbalance between renewable and non-renewable resources used in a process, the low ELR indicating relatively small environmental loading, while the high ELR indicating excessive use and according to calculations performed In the city of Chenaran indicates an imbalance between renewable and non-renewable resources because the amount of non-renewable resources is greater than renewable resources The ratio of renewable to non-renewable sources is 7.48 e + 16 to 1.09e + 19, which, as a result of the available resources and fuels involved, is much higher than that of the available resources. Adds to the imbalance. Using the ESI sustainability index, one can examine the ecological risk assessment in urban ecosystems obtained by combining both socio-economic performance and environmental impacts, calculated from the EYR and ELR ratios. , And measures the output of a system, relative to environmental pressure.The EYRs obtained in the city of Chenaran are 1.05 and ELR3.76e + 04 which indicate the stability (ESI) of the two together, the ESI obtained in the city of Chennar is 2.79e-05 and Emergy performance ratio is lower than environmental loading due to environmental pressure due to the use of non-renewable resources and high fossil fuels, which also have a direct impact on sustainability and lower the level of sustainability in the region. That is, of course, the growth and expansion of the city and the construction that has taken place, making more use of local resources and, consequently, reducing sustainability.
For this reason, policies such as turning a city into an "ecological city" and its related indicators and standards that pay close attention to the environment and environmental issues can provide an environment with high tolerance capacity


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