A device made from a highly porous material can extract water from air with the help of sunlight.
Atmospheric water is a largely untapped source of fresh water — equivalent to about 10% of the world’s lakes — but means of collecting it are inefficient, especially in areas where humidity is low. A team led by Omar Yaghi at the University of California, Berkeley, and Evelyn Wang at the Massachusetts Institute of Technology in Cambridge developed a water-trapping device from a metal–organic framework — a material that consists of metal ions linked by organic molecules. The framework’s nanometre-sized pores adsorb water vapour. Using only sunlight, the team heated the saturated device to extract the water, which was collected by the device's condenser.
Based on the performance of a prototype, the researchers estimate that one kilogram of the material could harvest 2.8 litres of water a day at a humidity level of just 20%. The device may help to relieve water shortages in arid regions, the authors suggest.