The economic development has serious impact on the nexus between water, energy, and environment. This impact is even more severe in Non-Organization for Economic Cooperation and Development (non-OECD) countries due to improper resource management. It is predicted that energy demand will increase by more than 71% in non-OECD as compared to 18% in developed countries by 2040. In Gulf Cooperation Council countries, water and power sector consume almost half of primary energy produced. In the past, many studies were focused on renewable energies based on desalination processes to accommodate fivefold increase in demand by 2050 but they were not commercialized due to intermittent nature of renewable energy such as solar and wind. We proposed highly efficient energy storage material, magnesium oxide (MgO), system integrated with innovative hybrid desalination cycle for future sustainable water supplies. The condensation of Mg(OH)2 dehydration vapor during day operation with concentrated solar energy and exothermic hydration of MgO at night can produce 24 h thermal energy without any interruption. It was showed that Mg(OH)2 dehydration vapor condensation produces 120 °C and MgO hydration exothermic reaction produces 140 °C heat during day and night operation, respectively, corresponding to energy storage of 81 kJ/mol and 41 kJ/mol. The produced energy can be utilized to operate desalination cycle to reduce CO2 emission and to achieve COP21 goal. The proposed hybrid desalination cycle is successfully demonstrated by pilot experiments at KAUST. It was showed that MgO + MEDAD cycle can achieve performance over UPR = 200, one of the highest reported ever.