Sorbent-based atmospheric water harvesting: engineering challenges from the process to molecular scale

Atmospheric water harvesting is an emerging technique that can potentially increase water access to water-constrained communities. Much research in this area has focused on the development of tailored microporous materials like MOFs or COFs with high water uptakes or small, proof-of-concept style devices for sorbent-based water harvesting. However, for sorbent-based water harvesting to be relevant for water-scarce communities these processes must be scaled up appropriately. The capture and separation of dilute water vapor from ambient air at scale raises engineering issues that have yet to be addressed. In this Perspective, we highlight some of these issues from the macro, meso, and micro-scale. We stress the importance of structured contactors that can effectively process the large air flow rates needed for sorbent-based water harvesting at scale. We also discuss techniques to accelerate the development of the next generation of porous molecular crystals and other classes of porous materials for water harvesting.