(18a) An Optimization Framework for the Evaluation of Energy-Water Systems for Agricultural Applications

The food-energy-water nexus (FEWN) dictates that food, energy and water are interconnected resources, and consequently, when decisions focusing on one resource are investigated, the other ones need to be considered. Therefore, the upcoming challenges of an evergrowing population, decreasing water sources, together with the impact of climate change can be tackled sustainably by the FEWN [1]. Further, arid, and semiarid regions are traditionally characterized by water scarcity. Here, technology-based water supply systems, i.e., water purification via RO desalination, can pose opportunities to harness saline water sources by utilizing varying energy supply systems for various applications [2, 3]. Additionally, there is an essential need to ensure the sustainable supply of food for a growing population [4]. However, FEWN studies have been conducted for various objectives, yet they have not been widely extended to irrigation planning [5].

Therefore, this work investigates the suitability and sustainability of energy-water options to meet varying water demands in agriculture systems. To do so, renewable, and non-renewable based energy sources, as well as varying sources of water are considered. Applicable water sources consist not only of ground or surface water, but also of purified water via RO desalination. A surrogate model is developed to incorporate all aforementioned alternatives, resulting in a mixed-integer non-linear (MINLP) optimization program. The MINLP can be optimized for an array of objectives, not only minimizing operational cost, but also satisfying a specified water demand as defined by the agricultural system. Additionally, the process costs of agricultural systems for maximization of the water utilization can be compared. Further, alternative water supply scenarios can be analyzed to identify trade-offs between competing irrigation and agriculture strategies. Thus, this work formulates a decision framework regarding energy-water systems, to fulfill agricultural scenarios, with minimal process costs, as well as maximum water utilization.

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[2] Marcello Di Martino, Styliani Avraamidou, Julie Cook, Efstratios N. Pistikopoulos. An Optimization Framework for the Design of Reverse Osmosis Desalination Plants under Food-Energy-Water Nexus Considerations, Desalination, 503, 2021. https://doi.org/10.1016/j.desal.2021.114937

[3] Marcello Di Martino, Styliani Avraamidou, Efstratios N. Pistikopoulos. Superstructure Optimization for the Design of a Desalination Plant to Tackle the Water Scarcity in Texas (USA), Computer Aided Chemical Engineering, 48, 763-768, 2020. https://doi.org/10.1016/B978-0-12-823377-1.50128-2

[4] Sarah Namany, Tareq Al-Ansari, Rajesh Govindan. Optimisation of the energy, water, and food nexus for food security scenarios, Computers and Chemical Engineering, 129, 2019, https://doi.org/10.1016/j.compchemeng.2019.106513

[5] Fatima-zahra Lahlou, Hamish R. Mackey, Gordon McKay, Udeogu Onwusogh, Tareq Al-Ansari. Water planning framework for alfalfa fields using treated wastewater fertigation in Qatar: An energy-water-food nexus approach, Computers and Chemical Engineering, 141, 2020, https://doi.org/10.1016/j.compchemeng.2020.106999