Those of us who always have enough water to drink can forget that there are plenty of places in the world without nearly enough water around.

Three quarters of the Earth's surface is water. But of course it's saltwater — and as many a shipwrecked survivor has found, just because there's water everywhere doesn't mean there's even a drop to drink.

Making it drinkable, where possible, is usually time-consuming, expensive, and messy.

So this is very exciting:

Engineers at MIT and in China are aiming to turn seawater into drinking water with a completely passive device that is inspired by the ocean, and powered by the sun.

In a paper appearing today in the journal Joule, the team outlines the design for a new solar desalination system that takes in saltwater and heats it with natural sunlight.

Here's a shot of this little wonder machine:

Doesn't look like much. But, if it works at scale, it could be a game-changer for world water access.

The machine operates by "allow[ing] water to circulate in swirling eddies, in a manner similar to the much larger 'thermohaline' circulation of the ocean." Heat from passive solar gain causes the water in the device to evaporate, leaving behind the heavy salt and re-condensing as potable, drinkable water.

Desalination systems tend to struggle with the salt factor: All that salt eventually gums up the works, making the process expensive and cumbersome. Yet this device permits the residual salt to "circulate through and out of the device, rather than accumulating and clogging the system."

As one of the researchers put it:

For the first time, it is possible for water, produced by sunlight, to be even cheaper than tap water.

The scientists claim that if the device was "scaled up to the size of a small suitcase," it could "produce about 4 to 6 liters of drinking water per hour" and "last several years before requiring replacement parts."

It's kind of a big deal.

The device "opens up the possibility for solar desalination to address real-world problems," one researcher said.

Exciting stuff. 🚰

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