Water-energy nexus and stochastic optimization in a isolated microgrid: application in arid zones of La Guajira in Colombia

Water-energy microgrids are regarded as a viable approach for generating well-being conditions and development in remote areas, such as the rancherías of Colombia's La Guajira region. Water and energy generation, storage, and management systems can be combined to form this microgrids. In this sense, this work proposes two optimal sizing and management models, which consider the relationship between water and energy (nexus) through a storage system with a hydropump. The proposed optimization models are deterministic and stochastic, both in two stages; in the first, the size of the installed renewable energy is minimized, while in the second, the drinking water generated by a desalination system is minimized, all while managing resources over a time horizon and different scenarios. Similarly, users with different water and energy requirements are interconnected, and variations in user consumption are compensated with the hydropump system, ensuring the microgrid's equilibrium over the time horizon. Linear and stochastic programming methods are used to solve the problem, whose formulations is implemented in the GAMS software. The results of the two optimization problems are compared with each other and the performance is evaluated in terms of sizing renewable energies, water production, resource management in the water-energy microgrid and costs.