Synthetic trees for enhanced solar evaporation and water harvesting

Abstract

Solar steam generation from a porous evaporator is a promising approach for harvesting fresh water. Parasitic heat loss can be reduced by using a 3D evaporator that extends above the free surface; however, capillary rise constrains the height of such structures to a centimeter scale. Here, we demonstrate solar steam generation from a synthetic tree, which uses transpiration instead of capillary rise to pump water up insulating tubes of any desired height. A nanoporous ceramic disk coated with graphite was used for the synthetic leaf, which was attached to the upper end of a vertical array of plastic tubes. Using a solar still, it was observed that the synthetic tree harvested approximately three times more condensed water than an equivalent bulk reservoir.