Researchers Develop Synthetic Tree for Harvesting Drinking Water

In Applied Physics Letters, Virginia Tech researchers developed a synthetic tree to enhance solar steam generation (SSG), reported Phys.org.

SSG is a promising renewable energy technology for water harvesting, desalination, and purification.

In order to execute these tasks, SSG turns solar energy into heat, with water from a storage tank continuously wicking up small, floating porous columns, reported Phys.org. Once water reaches the layer of photothermal material, it evaporates and steam is condensed into drinking water.

The technology is inspired by mangrove trees thriving along coastlines, according to the researchers studying this technology, reported Phys.org. 

A synthetic tree was created to replace the capillary action with transpiration, which allows the technology to pump water up insulating tubes of any height, according to Phys.org.

According to the researchers, the synthetic tree consists of a 19-tube array, covered by a nanoporous ceramic disk (the leaf). Each plastic tube is 6 centimeters high, just under 2.5 inches, with an inner diameter of 3.175 millimeters, about a tenth of an inch, reported Phys.org.

"We expect our tree-based solar steam generator will be of interest for applications in underground water extraction and purification," said author Jonathan Boreyko, reported Phys.org. "The ultimate goal is to achieve a suction pressure strong enough to pull ocean water through a salt-excluding filter without requiring a mechanical pump, analogous to how mangrove trees are able to grow in ocean water."

A challenge in scaling up the SSG technology is the limit in the capillary force beyond a certain column height. When this occurs, water is unable to wick fast enough to keep up with the evaporation process, so water begins to climb a porous paper towel, driving the water toward the evaporator.