Adsorption-based atmospheric water harvesting device for arid climates

Hyunho Kim,Sameer R Rao,Evelyn N Wang,Sungwoo Yang,Lin Zhao,Eugene A Kapustin,Omar M Yaghi

doi:10.1038/s41467-018-03162-7

Abstract

Water scarcity is a particularly severe challenge in arid and desert climates. While a substantial amount of water is present in the form of vapour in the atmosphere, harvesting this water by state-of-the-art dewing technology can be extremely energy intensive and impractical, particularly when the relative humidity (RH) is low (i.e., below ~40% RH). In contrast, atmospheric water generators that utilise sorbents enable capture of vapour at low RH conditions and can be driven by the abundant source of solar-thermal energy with higher efficiency. Here, we demonstrate an air-cooled sorbent-based atmospheric water harvesting device using the metal−organic framework (MOF)-801 [Zr6O4(OH)4(fumarate)6] operating in an exceptionally arid climate (10–40% RH) and sub-zero dew points (Tempe, Arizona, USA) with a thermal efficiency (solar input to water conversion) of ~14%. We predict that this device delivered over 0.25 L of water per kg of MOF for a single daily cycle.

Highlights

Water scarcity is a severe challenge in arid and desert climates
metal−organic framework (MOF)-801 was chosen in our study because it exhibits an adsorption step located around 20% relative humidity (RH) and is well-suited for the specific climate tested (Tempe, AZ, USA)
This approach opens possibilities to use MOFs with higher water uptake values and even lower regeneration temperatures, such as MOF-84111 or Co2Cl2BTDD12, in climates with ~20% RH even though their adsorption step is located at 25–30% RH

Summary

Introduction

Water scarcity is a severe challenge in arid and desert climates. While a substantial amount of water is present in the form of vapour in the atmosphere, harvesting this water by state-of-the-art dewing technology can be extremely energy intensive and impractical, when the relative humidity (RH) is low (i.e., below ~40% RH). We demonstrate an air-cooled sorbent-based atmospheric water harvesting device using the metal−organic framework (MOF)-801 [Zr6O4(OH)4(fumarate)6] operating in an exceptionally arid climate (10–40% RH) and sub-zero dew points (Tempe, Arizona, USA) with a thermal efficiency (solar input to water conversion) of ~14%. We predict that this device delivered over 0.25 L of water per kg of MOF for a single daily cycle. This corresponds to an increase of ~5× in comparison to operation without optical concentration and enabled complete regeneration with MOF-801

Methods

Results

Conclusion