Turning Salt Water into.. Fresh Water

With a little help from the sun.

This new method of distillation is game changing. Saving energy and providing a cost effective supply of clean water for developing nations. 

Removing the salt from sea water is an expensive and power sucking process. First, you have to boil the water, then the steam is captured and condensed to produce fresh water. The process requires a huge amount of energy to produce enough heat needed to boil the water.

Thanks to the team from the Nanotechnology Enabled Water Treatment (NEWT) at Rice University in Texas, there may now be a better way to take the salt out of saltwater. According to Water treatment expert and co-author of the study, Qilin Li:

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

So how do they do it?

By using a technique called membrane distillation. Hot salt water flows on one side of whats called a porous membrane and cold freshwater flows on the other side, the water vapour is then drawn from the hot to the cold side.

Unfortunately, due to the system running constantly, energy bills are still quite hefty, but still not as bad as the current method of distillation.

The new system’s technology is much more refined. The machine uses engineered nanoparticles to convert sunlight into heat. When the nanoparticles are added to the membrane, it’ll heat up by itself. Unlike the distillation method used at present, this method will not require energy to heat the water. It’s called "nanophotonics-enabled solar membrane distillation" technology, or NESMD. The team tested the NESMD chamber and managed to get a water production rate of about 6 litres per square metre per hour.

Depending on the water production rate you need, you could calculate how much membrane area you would need, For example, if you need 20 litres per hour, and the panels produce 6 litres per hour per square meter, you would order a little over 3 square meters of panels.

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