Water scarcity and the growing demand for sustainable water production present critical challenges, particularly in arid regions where conventional desalination technologies are energy-intensive and contribute to carbon emissions. This study proposes an innovative closed-loop system for atmospheric water harvesting, leveraging natural thermal gradients between high-altitude and low-altitude locations to condense water vapor from humid air. The system integrates high-thermal-conductivity materials, energy-efficient heat exchangers, and refrigerant fluids to achieve efficient heat transfer, enabling water condensation at minimal environmental cost. Key findings highlight the system's reliance on factors such as temperature lapse rates, material properties, fluid dynamics, and heat exchanger design for optimal performance. Case studies in the Kingdom of Saudi Arabia demonstrated the feasibility of applying this technology in regions with significant elevation differences, with temperature gradients and humidity levels supporting consistent freshwater production. Although quantitative performance metrics vary due to dynamic environmental conditions, the system shows promise in achieving significant reductions in energy consumption by leveraging natural thermal gradients, thereby minimizing reliance on fossil fuels and aligning with global carbon neutrality goals. This research underscores the potential of closed-loop systems as a sustainable alternative for water generation in energy-constrained environments. By addressing both water scarcity and climate change, the study lays the groundwork for further advancements in atmospheric water harvesting technologies and their integration with renewable energy systems. This study proposes an innovative closed-loop system for atmospheric water harvesting, leveraging natural thermal gradients between high-altitude and low-altitude locations to condense water vapor from humid air. The system integrates high-thermal-conductivity materials, energy-efficient heat exchangers, and refrigerant fluids to achieve efficient heat transfer, enabling water condensation at minimal environmental cost. Key findings highlight the system's reliance on factors such as temperature lapse rates, material properties, fluid dynamics, and heat exchanger design for optimal performance. By addressing both water scarcity and climate change, the study lays the groundwork for further advancements in atmospheric water harvesting technologies and their integration with renewable energy systems. Similar The system consists of a network of pumps and pipes carrying a refrigerant fluid, which operates in conjunction with the surrounding thermal environment. By capitalizing on the cooler temperatures at higher altitudes and the warmer air at lower elevations, the refrigerant undergoes a cyclic process that efficiently reduces ambient temperatures. This temperature reduction promotes the condensation of freshwater from warm, humid air, effectively mimicking the natural processes of dew formation but on a scalable and controlled basis. 1 Full size image Schematic diagram of the proposed closed-loop system leveraging natural thermal gradients for sustainable atmospheric water harvesting At higher elevations, the cooler ambient temperature causes the fluid in the elevated pipeline to lose heat, resulting in a temperature decrease. Conversely, the fluid near sea level absorbs heat from the warmer ambient environment, thereby cooling the surrounding air. The denser, cooler fluid from the elevated pipeline naturally flows to replace the warmer fluid downstream via natural circulation. It does so by capturing humid, hot air near the surface and condensing water vapor as the air interacts with the cooled fluid. This study investigates the application of this technique in a specific location in the Kingdom of Saudi Arabia. The country faces significant challenges due to its limited natural freshwater resources, dependence on energy-intensive desalination systems, and ongoing efforts to transition to clean and sustainable energy solutions [ 62 ]. Figure  3 illustrates a heat map showing the geological elevation above sea level for a selected section of the western coastline of the Kingdom of Saudi Arabia along the Red Sea. $${T}_{dew}=\frac{b \left(\text{ln}RH+\frac{a T}{b+T}\right)}{a-\left(\text{ln}RH+\frac{a T}{b+T}\right)}$$ (9) where \({T}_{dew}\) is the dew point temperature; \(T\) is the ambient air temperature; \(RH\) is the relative humidity ratio; \(a\) and \(b\) : empirical constants; typically, a = 17.269 and b = 237.3. Table 2 Required temperature drops for water condensation from humid air relative to ambient temperature (Red indicates high values while green indicates low ones) Full size table Fig. 5 Full size image Required temperature drops for water condensation Fig. 6 Full size image Daily humidity variations in Mastabah City throughout the year 2023 5 Conclusion This study proposed and analyzed a novel closed-loop system for atmospheric water harvesting by utilizing natural thermal gradients between high and low elevations. The system leverages the temperature lapse rate to condense water vapor from hot, humid air, offering a sustainable solution to freshwater scarcity while addressing the energy-intensive nature of traditional desalination technologies. A review on the water-energy nexus for drinking water production from humid air. Renew Sustain Energy Rev. 2020;120:109627. https://doi.org/10.1016/j.rser.2019.109627 . Article Google Scholar Zhao D, Tan G. 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