Regional-scale water-energy nexus management by a mixed Possibilistic-Flexible robust nonlinear programming model

With the severe shortages and increasing demands of water and energy resources, water and energy system analysis and management have attracted more and more attentions recently. In this study, a nonlinear mixed Possibilistic-Flexible Robust Water-Energy nexus model, named PFRWE, is developed for supporting integrated planning of water and energy nexus at a regional-scale. The developed PFRWE model has improved upon the existing methods for water-energy nexus through incorporation of fuzzy flexible programming, fuzzy possibilistic programming, robust programming and mixed integer nonlinear programming into a general framework. Robustness of the model and solution processes will be improved, including optimality robustness and feasibility robustness, based on the preferences of decision makers. Application of the PFRWE model to a real-world case study in Liaoning province, China has tested its applicability in regional water-energy nexus system management. Optimal decisions on the amounts of water production and electricity generation, new power and water plants construction, the types of new power and water plants, amounts of water consumption for electricity generation, amounts of electricity consumption for water production, and amounts of imported electricity are obtained. Tradeoffs between robustness and water production, electricity generation, imported electricity and expected total system profit are analyzed. By comparing the solutions of the PFRWE model and the deterministic model, it is found that the PFRWE model has advantages in maintaining feasibility and reducing variations of objective value under higher robustness or optimizing objective value under lower robustness.