Continuous humidity pump and atmospheric water harvesting inspired by a tree-pumping system

Dehumidification not only regulates the relative humidity (RH) of buildings with reduced cooling costs but also provides a potential drinking water source for residents. Desiccant-based dehumidification has a lower energy consumption than the condensation-based method; however, the former requires successive regeneration of used sorbents and is, therefore, bulky. In this study, by mimicking transpiration in trees, we propose a humidity pump (HP) that continuously dehumidifies rooms by creating a continuous driving force for water wicking. Meanwhile, we investigate the potential of the HP by combining it with atmospheric water harvesting systems. We use activated carbon-lithium chloride composites since they have proven to possess high sorption capacity and strong capillary effect. We develop a small prototype, and our results show that it can maintain the RH between 50% and 70% while producing 1.3–3.25 g water per day. By advancing these techniques, we create an opportunity for developing more energy-efficient humidity regulation and atmospheric water harvesting systems.