Millions upon millions of people worldwide, especially in developing nations, languish without clean drinking water. Yet water covers most of the planet’s surface. The trouble is that most of that abundant water is saltwater. Scientists have been coming up with a variety of ways and devices to turn saltwater into freshwater.
Here now comes one of the latest invention … thanks to the Japanese art of origami, or paper folding.
The invention relies on solar steam generators, a type of boiler that produces clean water by converting energy from the sun into heat. The heat causes seawater in the boiler to evaporate even as salts and other impurities are filtered out. The resulting steam can be collected and condensed into freshwater.
Yet solar steam generators are very efficient as they lose lots of energy from heat dissipation. How to change that? Scientist Peng Wang and his colleagues decided to see whether they could improve the generators’ energy efficiency by designing a three-dimensional photothermal material to replace the flat material in use in steam generators. They based their new design on the Miura fold of origami, which consists of interlocking parallelograms that form “mountains” and “valleys” within a three-dimensional structure.
The researchers, who published their findings in a paper “Nature-Inspired, 3D Origami Solar Steam Generator toward Near Full Utilization of Solar Energy” in the journal ACS Applied Materials & Interfaces. created a solar steam generator by “depositing a light-absorbing nanocarbon composite onto a cellulose membrane that was patterned with the Miura fold,” a press release explains.
“They found that their 3D device had a 50 percent higher evaporation rate than a flat 2D device. In addition, the efficiency of the 3D structure approached 100 percent, compared with 71 percent for the 2D material,” it adds. “The researchers say that, compared to a flat surface, origami ‘valleys’ capture the sunlight better so that less is lost to reflection. In addition, heat can flow from the valleys toward the cooler ‘mountains,’ evaporating water along the way instead of being lost to the air.”
Cool stuff? You bet. The invention isn’t groundbreaking, to be sure. Yet it can come in handy in arid, sundrenched regions of the world by making it more efficient to turn saltwater into freshwater.
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