Integration of hygroscopic salts into natural fibers for enhanced dew condensation

Abstract

Water scarcity affects ~4 billion people globally, with Sri Lanka’s dry zone particularly impacted due to prolonged dry seasons, groundwater depletion, and saltwater intrusion. Traditional solutions such as dams, desalination, and groundwater extraction are often costly, energy-intensive, and unsuitable for decentralized communities. Atmospheric water harvesting (AWH), especially dew harvesting, offers a low-energy, scalable alternative that produces high-purity water by exploiting night-time radiative cooling. [1] Two main AWH types exist: passive systems, which rely on natural cooling, and active systems, which use external energy for higher yields [2]. Hybrid systems combining radiative cooling and solar regeneration are emerging for enhanced efficiency. This project develops a sustainable, locally adapted dew harvesting system by integrating hygroscopic calcium chloride (CaCl₂) into water hyacinth fibers—an abundant, invasive plant in Sri Lanka. The combination leverages CaCl₂’s strong moisture absorption and the fibers’ high porosity, hydrophilicity, and radiative cooling capability. The system addresses gaps in existing research, aiming to boost yields in humid tropical climates while creating value from invasive biomass. It offers a cost-effective, deployable solution for rural and urban water-stressed communities using locally available materials and renewable energy. The primary aim of this project is to develop an efficient and sustainable atmospheric dew harvesting system using radiative cooling textile material.