According to a recent article in Science, researchers have developed a new material that speeds the process of evaporation, enabling small solar stills to provide all the drinking water needed for a single-family residence.
Old-school solar stills are not much different than a backwoods whiskey still, only they use the sun as a heat source. Think black tank filled with water and topped with clear glass. As the tank absorbs the sun’s heat, the water evaporates in the tank and leaves the contaminates behind. The vapor condenses on the glass from which it drains off and is collected as clean water. It’s slow, but effective. Too slow, however, to make much of a dent in one family’s daily drinking water needs. According to the Science article, commercially available solar stills produce about 0.3 liters of water per hour per square meter of the covered water’s surface area. The average person requires about three liters of water a day for drinking. A small family would require a still about five square meters operating at optimum output to produce enough water to live on.
By using hydrogels, however, a team of materials scientists at the University of Texas in Austin have increased output for solar stills by speeding up the evaporation of water. At the higher water production rate afforded by this new technology, a solar still one square meter in size reportedly could produce about 30 liters of clean drinking water per day, enough for a small family.
Of course, this water technology break-through has enormous potential not just in the water-starved West, but globally. According to figures cited in the article, 783 million, or nearly one in 10, people worldwide, lack access to clean drinking water, and spend a collective 200 million hours a day obtaining water from distant sources.