From the most parched areas of Saudi Arabia to water-scarce areas of the western U.S., the idea of harvesting fog for water is catching on. Now, a novel approach to this process could help meet affected communities’ needs for the life-essential resource. Scientists describe their new, highly efficient fog collector, inspired by a shorebird’s beak, in the journal ACS Applied Materials & Interfaces.
Cheng Luo and his doctoral student, Xin Heng, explain that deserts and semi-arid areas cover about half of the Earth’s land masses. In some of these places, trucks bring in potable water for the people who live there. To find a more sustainable way to get water, these communities, which can’t draw water from underground or surface supplies, have turned to the air — and to nature for inspiration. They implement methods adapted from those that desert beetles, cacti and grasses use to catch water from the misty fog when it rolls in. But existing techniques require complicated, costly processes or collect only a small fraction of the water that fog has to offer. For new ideas, Luo’s team turned to shorebirds with long, thin beaks.
By opening and closing their beaks, shorebirds drive food-containing liquid drops into their throats. The researchers mimicked this phenomenon by building simple, fog-collecting, rectangular “beaks” out of glass plates connected by a hinge on one side. When open, the plates provide a large surface area where beads of fog condense. When the plates close, then re-open, the droplets slide toward the hinge and into a collection tube. A single 10-inch by 4-inch prototype “swallowed” about a tablespoon of water in 36 minutes. Over two hours, it harvested 400 to 900 times more water than both natural and other artificial fog-collectors.