Solar Adsorption-Based Atmospheric Water Harvesting Systems: Materials and Technologies

Abstract

Freshwater scarcity is a major problem threatening many countries worldwide, notably those with arid climate conditions that lack access to fresh water. Humidity harvesting represents a reliable source of providing fresh water, especially if it can be extracted affordably and efficiently. Sorption-based atmospheric water harvesting (AWH) has the merit of being powered economically and sustainably by utilizing waste heat or solar energy compared to other AWH techniques. The first part of this chapter comprehensively presents the working principles of the atmospheric water harvesting technology. Afterward, a detailed appraisal of state-of-the-art sorption materials, such as activated carbon fiber, zeolite, silica gel, metal–organic frameworks, calcium chloride with various host materials, and hydrogels, where its adsorption isotherms and kinetics are examined in detail. The challenges and prospects of these sorption materials are also demonstrated. Moreover, numerous designs of solar-powered atmospheric water harvesters, including fixed and movable installations, are summarized and categorized. For the sake of comparison, operation concepts, advantages, disadvantages, and freshwater production capabilities are indicated. In that regard, the viability of those systems is also exhibited under different meteorological conditions. Eventually, the obstacles and limitations that hinder their utilization and future research directions are explored. Accordingly, AWH technology is introduced as a promising solution for freshwater supply, particularly in rural areas and arid deserts where water and energy are scarce.