Science and Technology, Technology

Scientists Are Using Solar Energy To Turn Salt Water Into Fresh Water

The technology is a "nanophotonics-enabled solar membrane distillation technology" which means it's converting sunlight into heat. This saves on massive amounts of heating costs needed from the traditional method.

In a massive breakthrough, scientists have found a unique process to turn salt water into fresh water. This could be big news for families and towns in need of water.

Research published in the Proceedings of the National Academy of Sciences details an “off-grid technology is capable of providing sufficient clean water for family use in a compact footprint, and it can be scaled up to provide water for larger communities.”

Our current process for desalination (removing salt from water) is costly and inefficient. In plants across the world salt water is boiled and the condensation is collected to produce fresh water. It takes extreme amounts of heat and energy.

In contrast, the new process could be a ‘game changer’ according to statements from the Center for Nanotechnology Enabled Water Treatment (NEWT) at Rice University in Texas.

“Direct solar desalination could be a game changer for some of the estimated 1 billion people who lack access to clean drinking water.”

The process is called membrane distillation. In this method, hot salt water and cold fresh water are run along the sides of a thin membrane, from there a vapor is collected from the cold side and turned into fresh water. The technology is a “nanophotonics-enabled solar membrane distillation technology” which means it’s converting sunlight into heat. This saves on massive amounts of heating costs needed from the traditional method.

It’s a reduction in costs, but it still draws a volume of heat requirement. Heat is continuously lost from the hot side of the membrane to the cold.

This scaled up test bed of NEWT’s direct solar desalination technology uses carbon black nanoparticles that convert as much as 80 percent of sunlight energy into heat. Results from an earlier prototype showed the technology could produce as much as six liters of freshwater per hour per square meter of solar membrane. (Photo by Jeff Fitlow/Rice University)

While it still has it’s drawbacks, the technology is far more efficient and manageable. In a proof of concept study researchers managed to draw 6 litres of water per hour from a “chamber about the size of three postage stamps and just a few millimeters thick.”

When scaled up, we can see how effective this would be on a larger scale. “Depending on the water production rate you need, you could calculate how much membrane area you would need. For example, if you need 20 liters per hour, and the panels produce 6 liters per hour per square meter, you would order a little over 3 square meters of panels.” Says Qilin Li, a corresponding author on the study.

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Jamie is an amateur astronomer and every day space geek.