Developing an integrated model for allocating resources and assessing technologies based on the watergy optimal point (water-energy nexus), case study: a greenhouse

Water-energy nexus approach analyses water and energy interactions to provide sustainable usage of resources. This study incorporates a comprehensive bottom-up optimization model to assess the combination of technologies based on the water-energy nexus (watergy) optimal point. To achieve this goal, the watergy reference system is introduced according to six principles of watergy system. In this study, a new method is developed by adding an integration layer to the optimizing model with the objective function of the minimum total cost. In this layer, the demands for water and energy, for supplying the water and energy services, are calculated endogenously. A sensitivity analysis is performed by presenting six scenarios for greenhouse case study. Results indicate that the drainage recycling, combined heat and power, and photovoltaic were chosen at the watergy optimal point. Compared to the base case scenario, the maximum achievable reduction in the total cost of production is 31% in the most costeffective scenario (Scenario B). Also, among the modelled scenarios, the optimal combination of technologies could result in reducing the use of water, electricity, and fertilizer by 18%, 31%, and 25% respectively.