While solar stills have been around for some time already, there’s plenty of room for efficiency improvements. In a bid to do exactly that, scientists from Virginia Tech have developed a mangrove-inspired “synthetic tree” that mimics the natural process of transporting water from the roots to the leaves.
Currently, most variations of solar stills use an absorbent material to wick up non-potable water from a reservoir. Once it reaches the upper part of the device, the water is heated by sunlight, after which it evaporates into the air. The water vapor then hits a sloped ceiling and condenses, running down into a collection tray.
As explained by New Atlas, most of the existing solar stills work using capillary action, where the liquid climbs up through a narrow space by sticking to the edges and dragging other molecules upwards thanks to the liquid’s highly cohesive properties. Scaling this method, however, is rather challenging.
To overcomes this obstacle, the Virginia Tech team looked to nature for a more efficient water-wicking system. When it comes to plants, capillary action plays a minor role in the transportation of water. Most of the job is done through the process of transpiration — which allows plants to efficiently suck water up from their roots, through their stems and branches, and out through their leaves as water vapor.
Inspired by the transpiration process of plants, the research team developed their own water purification design. Their synthetic tree is made up of 19 tubes, 2.4 inches high, with an inner diameter of just 0.1 inches. The tubes pull water up to a small porous ceramic disk coated in graphite, which acts like the leaf as the evaporating surface.
After testing their new design, the scientists found that the synthetic tree was able to harvest three times more water than using a bulk reservoir alone. Next, the team plans to test taller trees, add more leaves, and use membranes to filter salt out of the water.