Salty No More: Desalinating Seawater with Sunlight

Fagjun | Published 2017-06-22 03:09

Potable water is a necessity, and obtaining it should be as easy as possible.
[Photo by Aman Bhargava]

There is a new energy-efficient way of desalinating seawater with the power of the sun.

The traditional methods of desalination, or taking the salt out of saltwater, can be energy intensive. Desalination aims to produce fresh or potable water from undrinkable saltwater, which can come in handy for a number of applications.

We usually desalinate saltwater through a method called distillation. This entails boiling the water until it's all vapor. Then, we cool the vapor down in condensation tubes and end up with potable water. Of course, this method requires quite a lot of energy. Boiling water alone is already energy-intensive; thus, distillation isn't the most energy-efficient way to desalinate saltwater.

Thus, a team of researchers have decided to find a more energy-efficient desalination technique. This means that they've taken the most energy-intensive part—boiling the water—out of the equation. However, can this system work without having to boil the water?

Energy Efficiency and Desalinating Seawater

Condensation from water vapor can turn into potable water.
[Photo by Mark Doda]

The Center for Nanotechnology Enabled Water Treatment (NEWT) at Rice University has been working on new technology that revolutionizes desalination. They came up with a system called "nanophotonics-enabled solar membrane distillation", or NESMD. This system only needs hot, not boiling, water.

This is how the system works: there's a very thin membrane separating hot and cold water. Water vapor from the hot water goes through the membrane to the side with cold water. This separates the salt and thus produces potable water.

The membrane itself isn't just any sort of membrane. Researchers as NEWT have infused these membranes with nanoparticles that turn light from the sun into heat. Thus, all the system needs is sunlight in order to generate heat and hot water. There's no need for active heating to facilitate desalinating seawater, thus making the system use less energy than distillation does.

Of course, this doesn't mean that the system requires very little, negligible power. It does still need enough power for a pump that pushes water through the system, but that's mostly it. Just a few solar panels will be enough to keep the system going.

Potable Water and a Minimal Carbon Footprint

Remote areas can have easier access to potable water with the NESMD.
[Photo by Maxime Staudenmann]

The system can be invaluable in certain places where potable water as well as energy sources may be hard to come by. Places like evacuation sites, offshore rigs, and remote rural villages can definitely benefit from this system. All they'll need is sunlight, and, of course, the system itself. People in these places can avoid disease and other complications that stem from the lack of access to clean water.

It's also worth mentioning that the use of minimal energy is a huge plus. Individual households and entire communities can minimize their carbon footprint with the use of the NESMD. Thus, not only is the system quite simple, it's also effective, efficient, and environmentally sound.

NEWT aims to develop the system into compact units that can reach far-flung, hard-to-access areas. Users can calculate how much membrane they would need based on their estimated water consumption. Desalinating seawater can be easier, more energy-efficient, and more accessible to areas and communities that sorely need it.

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