Abstract
The current worldwide state of energy scarcity and low waste utilization has led to a decrease in the supply of ecological services, something that seriously affects the development of cities. In this study, we propose an urban self-circulation design based on multiple systems within the traditional biogas, wetland, rainwater, solar power, and urban farm systems framework to achieve effective improvements in urban waste utilization and the optimization of the urban waste–energy flow cycle. Emergy conversion is used to evaluate system optimization, and the simulation results show that the novel proposed system can effectively improve urban waste utilization with an energy output rate of 3.18 × 10, an environmental load of 4.27 × 10−2, and a sustainability index of 7.45 × 102 in the core system; additionally, it can improve resource utilization of small-scale cities with an energy output rate of 1.85 × 100, an environmental load of 1.20 × 100, and a sustainability index of 1.54 × 100 in the total system. The inter-system energy flow model can significantly optimize urban energy systems based on ecological models with low-emergy resource input, including biogas systems and urban farm systems. This model can reduce the environmental load and effectively compensate for the reduced supply capacity of ecosystem services caused by urbanization, making it suitable for extension to other small-scale built environments that are relatively independent and rich in natural resources.
Highlights
As urbanization continues, human demand for ecosystem services, especially energy supply, has increased dramatically.Ecosystems provide a range of services that are essential to supporting economic performance and human well-being; these services are referred to as ecosystem services [1,2,3].Ecological services represent the contribution of ecosystems to human well-being and are defined in terms of their specific benefits to individuals or society [4]
Taking into account the urban energy sustainability and environmental impact studied this study uses three emergy indexes—namely, the emergy output rate (EYR), environmental load rate (ELR), and emergy sustainability index (ESI)—each of which we describe below
By analyzing the sustainability index, we found that the values of the biogas system and urban farm system changed significantly; those of the values of the solar power system increased significantly (Figure 11)
Summary
Human demand for ecosystem services, especially energy supply, has increased dramatically.Ecosystems provide a range of services that are essential to supporting economic performance and human well-being; these services are referred to as ecosystem services [1,2,3].Ecological services represent the contribution of ecosystems to human well-being and are defined in terms of their specific benefits to individuals or society [4]. Human demand for ecosystem services, especially energy supply, has increased dramatically. Ecosystems provide a range of services that are essential to supporting economic performance and human well-being; these services are referred to as ecosystem services [1,2,3]. Ecological services represent the contribution of ecosystems to human well-being and are defined in terms of their specific benefits to individuals or society [4]. The resources needed for human survival and development are derived from natural ecosystems. The urbanization process has largely led to a decrease in the supply capacity of ecological services. Forest, pastoral and agro-ecosystems are being transformed into human-dominated ecosystems at an unprecedented scale and speed
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