Ecological network analysis and optimization of urban water metabolic system in context of energy nexus

The interconnectivity of energy and water resources is inherent within the urban water system. To meet the energy demands of the urban water system and optimize resource utilization, effective planning and management are essential. In this paper, a new framework incorporating network analysis and optimization model was developed to decrease energy consumption while enhancing water resource network resilience in Beijing, China. First, we established a water metabolic network (WMN) using ecological network analysis (ENA) to determine the water resource flow in each process. Then, the WMN performance was evaluated utilizing a set of indices derived from the ENA approach. Finally, an optimization model was set up with the objectives of minimizing energy consumption and maximizing network resilience, using non-dominated sorting genetic algorithm II (NSGA-II) to obtain the Pareto-optimal solutions. The results indicated that WMN was generally operated at a status of low efficiency, high redundancy and robustness. Totally 0.70 billion m3 of water resources and 2.77 billion kWh of energy flow can be saved after the dual-objective optimization. The proposed framework may help optimize water metabolic network to decrease energy consumption while enhancing network resilience for a better urban water system planning, maintenance and management.