Water may be a scarce commodity in arid regions, but a sufficient amount of the resource exists in the atmosphere, awaiting collection. A device has been devised by MIT engineers to capture atmospheric water and satisfy potable water needs.

The compact, portable system traps moisture by means of absorbent-coated fins, after which the harvester is heated to deliver potable water. Heating for water desorption can be driven by solar energy or waste heat. The fins are formed by installing a copper sheet between copper foams which have been layered with a commercially available (silico)aluminophosphate zeolite. The prototype described in ACS Energy Letters features a series of thin vertical fins spaced 2 mm apart on the copper base sheet. This configuration maximizes water collection from air characterized by 10% relative humidity.

During testing, the fins trapped and released moisture within an hour as the base sheet reached 363° F. If operated for 24 hourly cycles, the water harvester with 1 l of absorbent coating on the fins can generate about 1.3 l of potable water daily at 30% relative humidity. This represents a water supply up to five times greater than that provided by previously developed devices.