The UN estimates that 2.2 billion people lack safely managed drinking water. Across the globe, over 300 million people rely on desalinated water for part or all of their daily needs. There are more than 22,000 desalination plants around the world. In the U.S., about 5 million people receive water from desalination, mostly in states like California and Florida.
Typical desalination plants use techniques like reverse osmosis and thermal distillation. These processes are energy-intensive, require pre- and post-water treatment, and leave behind brine, a concentrated saltwater byproduct. The brine is often deposited back into the ocean, raising the local salt level and lowering oxygen in the water, wreaking havoc on sea life.
Researchers at the University of Rochester have developed a new solar-thermal desalination process that does not leave behind any brine and requires no chemical additives to pre-treat the water.
The technology uses specially-etched solar panels whose active regions pull a thin layer of water across the surface, absorb solar radiation, distill the water, and deposit the leftover salts and minerals into the panels’ passive region. The laser-etched regions make the surface self-cleaning. The fresh water is extracted, and the remaining salts end up in the passive region where they can be collected and removed.
So far, the new desalination technology has been demonstrated only as proofs of concept on small-scale devices, but the researchers believe that it is inherently scalable.
