Fog-catching fabric could improve water collection in deserts

Joel Winston in SciDev.net:  A novel and affordable fabric may improve the efficiency of water collection from fog, helping to provide freshwater in desert areas. Researchers from the Eindhoven University of Technology (EUT), in the Netherlands, and Hong Kong Polytechnic University, China, turned a  cotton fabric into a water-collecting material by coating it with a polymer called PNIPAAm.

The fabric switches between absorbing moisture directly from the air when it is foggy and cold, and releasing it as water at warmer temperatures, according to a paper to be published on 21 February in Advanced Materials.

Every kilogramme of the sponge-like fabric can absorb around 3.4 litres of water from the air.  When the ambient temperature rises, the material's microstructure changes and the water is released. These processes are repeatable, raising hopes the fabric could act as an autonomous water-collecting device.

The team hopes the material could be used to harvest water in dry coastal areas, such as the Namib Desert, in Namibia, where rainfall is scarce but ocean air currents frequently bring vapour-carrying fogs.

The temperature range within which the fabric collects, and then releases, water is similar to the typical daytime highs and night-time lows seen in deserts....

A dune in the Namib Desert, shot by Teo Gómez, who has released it into the public domain