this post was submitted on 28 Sep 2023
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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.

The researchers estimate that if the system is 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. At this scale and performance, the system could produce drinking water at a rate and price that is cheaper than tap water.

https://www.cell.com/joule/fulltext/S2542-4351(23)00360-4

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[–] FlyingSquid@lemmy.world -3 points 1 year ago (3 children)

Increasing ocean salinity is a very bad idea.

[–] Aceticon@lemmy.world 7 points 1 year ago* (last edited 1 year ago) (1 children)

At the end of its cycle - after use and via sewage systems/rivers - that water will end back in the ocean, were the salt went.

In fact not putting the salt in the ocean and instead storing it as a solid on land would over time reduce the ocean salinity as the water would end back in the ocean but not the salt.

[–] Khotetsu@lib.lgbt 2 points 1 year ago (1 children)

You're correct, but so are they. In the long term and at a large scale, it balances out, but in the short term, there is a very real concern about local salinity levels wherever you're reintroducing that salt to the ocean. Keeping up with the desalination plants will be a tricky business of logistics to avoid destroying the ecosystem around where you're dumping that salt.

Adding the salt into water leaving sewage systems before it returns to the ocean might be a good idea, as you could basically kill two birds with one stone: put the salt back in the ocean while also avoiding damaging the local ecosystem with the fresh water of the sewage system reducing local salinity levels. But I'm no engineer or water treatment specialist, so I dunno if that's at all a real solution.

[–] havokdj@lemmy.world 1 points 1 year ago* (last edited 1 year ago)

You hit the nail in the head on that first part. People don't realize exactly how long the water cycle takes to recover to natural levels when human intervention is accounted for. This is something that we are talking centuries to make happen, and that's assuming we go at a steady rate rather than desalinate like we are trying to suck the oceans dry.

[–] Ejh3k@lemmy.world 6 points 1 year ago (1 children)

Increasing ocean salinity is a good idea. With all the ice caps melting, salinity is going further down. The salt makes the water denser, and that helps regulate temperatures. Also, the salinity differences between the poles and equator create a general current that cycles the water.

Plus, removing the salt and eventually returning the water is bad for ocean life. Their bodies need the salt.

[–] Coreidan@lemmy.world 0 points 1 year ago

Someone doesn’t understand what zero sum means