Advancements in radiative cooling structures for atmospheric water harvesting: A comprehensive review

Atmospheric water harvesting (AWH) presents a promising technology to address global water scarcity concerns. Utilizing radiative cooling (RC) surfaces to condense atmospheric water vapor has emerged as an effective passive AWH method, requiring no external energy input. Recent advancements in scalable RC distributed particle or porous structures have proven their ability to cool surfaces below the dew point, enabling extensive AWH throughout the day. Furthermore, combining RC systems with other passive AWH technologies, such as sorption technology and morphology optimization, shows promise in increasing water yields and enhancing adaptability to diverse geographical conditions. Additionally, integrating RC technology with solar desalination systems extends water production into nighttime hours and optimizes vapor condensation throughout the day, further enhancing water yield. This review offers a comprehensive examination and critical assessment of RC-based AWH technologies and their integration with other passive AWH methods and solar desalination approaches documented thus far. The study highlights significant potential for developing passive AWH technologies integrated with RC systems, demonstrating effectiveness across various geographical areas and climate conditions. Moreover, the review identifies existing research gaps, delineates future avenues for development, and discusses challenges that researchers in this field may face, especially concerning RC material and condenser structure development.