Sustainable evaporative cooling driven by saline water sources: opportunities, challenges and solutions

Traditional air-conditioning (AC) systems contribute significantly to a building's total energy consumption, and improving its energy efficiency is crucial for energy conservation and carbon emission reduction. The evaporative cooling (EC) is recognized as a sustainable cooling technology to replace conventional AC systems due to its high efficiency and environmental friendliness, particularly in hot and dry regions. However, EC's high consumption of freshwater limits its application in water-scarce regions. Using saline water sources offers a promising solution to reduce reliance on freshwater and expand EC's potential, but a systematical analysis over this technology is missing in the literature. This study explores the opportunities, challenges, and solutions associated with saline water-driven EC systems. The review begins by examining the water footprint of existing EC systems to emphasize the necessity of utilizing alternative water sources. Next, potential impacts of saline water on the cooling performance and durability of EC are analyzed. Subsequently, water pre-treatment methods that can mitigate fouling and reduce contamination of saline water on EC are summarized. Finally, the possibility of integrating EC with desalination for cogeneration of both freshwater and cooling is explored. The findings suggest significant potential for saline water-driven EC and highlight the possibility of combining EC with desalination for water-cooling cogeneration. However, challenges such as biofouling and partial wetting remain to be addressed. These results provide valuable insights for the effective use of saline water in EC systems, reducing reliance on freshwater and enabling EC applications in water-scarce regions.