According to United Nations estimates, more than two billion people around the world lack access to safely managed drinking water. As freshwater becomes increasingly scarce, communities from California to the Middle East are turning to desalination to convert seawater into drinking water.
But conventional desalination comes with significant drawbacks. Reverse osmosis and thermal distillation require large amounts of energy, and they produce concentrated saltwater, or brine, that can harm marine ecosystems when it’s discharged back into the ocean.
Now, researchers at the University of Rochester in New York have developed a solar-powered approach that could address some of these problems.
The new system uses black metal etched with femtosecond lasers to create a surface that is super light-absorbing and superwicking (or extremely attractive to water).The surface draws a thin layer of water across the panel, where sunlight evaporates the water and leaves behind salts and minerals. The salts and minerals are directed away from the active surface and deposited in an untreated, passive region of the panel, allowing the system to continuously produce fresh water.
Tests using water from the Pacific, Atlantic, and Indian oceans showed that the system can produce fresh water while recovering nearly all of the remaining salts in solid form.
Researchers have also shown that the technology can be modified to extract lithium from those materials, potentially turning a desalination byproduct into a valuable resource.
The researchers say the technology is still in the proof-of-concept stage, but its scalable design could eventually help expand access to fresh water while reducing the environmental impacts of desalination.
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References:
New method turns ocean water into drinking water, without waste
