Solar Technology Takes the Salt Out of Ponds on the Cheap

walker lake nevada photo

Image credit: Wikimedia Commons

Around the world, closed-basin lakes, like the Great Salt Lake, the Alton Sea, and the Aral Sea, are losing water as a result of human and natural processes. With no outflow and high salt and mineral saturation, these lakes, through drought and evaporation, are being transformed into highly saline pools and some, like Walker Lake in Nevada, have become toxic to aquatic life.

A new system, developed by a doctoral candidate at the University of Nevada in Reno, uses solar-heated ponds and an innovative membrane technology to rescue these lakes with low-temperature desalination.By creating an artificial salt-gradient in pools, Francisco Suarez has been able to trap heat energy that can later be used to power a membrane desalination system recently patented by the university. He explains that his system:

Can operate 24 hours a day using the stored energy. Very little electricity would be used...for every surface acre of solar pond we can make three acre-feet of freshwater in about one year.

Through lab tests and a small-scale prototype, Suarez has shown that after two weeks, the pools can reach the temperature necessary to become functional. He said that in that period, "the temperature in the bottom of the solar pond increased from 68 to 126 degrees Fahrenheit," before adding that "even though the insulating layer is being eroded by double-diffusive convection, the solar pond remained stable."

walker lake photo

Walker Lake, Nevada. Image credit: Uncle Ariel/Flickr

If it can scale up even more, the system presents several advantages over other concepts because, as Suarez explained, "renewable energy is used, the system is low maintenance and the stratification process that helps drive the process uses the salts from the lake itself."

Coupled with other mitigation efforts, the solar ponds and membrane desalination system could help transform a now-toxic lake into the safe habitat it once was.

Read more about desalination:
Ask Pablo: What's The Problem With Desalination?
Ottawa Student Could Make Water Desalination 600-700% More Efficient
Low Temp Desalination Technology From New Mexico Water Resources Research Institute

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