New method turns ocean water into drinking water, without waste

6/5/2026 at 5:21:31 PM

There is a fundamental minimum amount of energy needed to desalinate: you can't take less energy to do it,than you could gain back (from osmotic pressure) if you allowed the desalinated water to expand a cylinder containing the residual brine. This is large. This paper is a thermal method, so it doesn't have an electricity input, but to justify their efficiency claim, they should really compare against what you could do by using the same surface area for solar panels, driving a conventional setup. My (limited) understanding is that conventional reverse osmosis is not far from the theoretical optimum, energy-wise, the main difficulties being operational (the membranes need declogging). And of course RO is more expensive than rain.

This paper is interesting, however, in directly producing crystalline salt, which is lower volume than brine and easier to dispose of, maybe even valuable.

by ajb

6/6/2026 at 3:10:54 PM

I always thought that if separating water and salt were easy, our bodies would have evolved to do it so that we'd be able to drink sea water and be fine. It must have been so expensive that searching for fresh water was worth it or there were plenty of fresh water that it was never a evolutionary pressure. Evolving kidneys capable of concentrating urine beyond 3 something percent concentration (sea water) perhaps required a massive restructuring of our internal organs and a huge constant energy expenditure, so we kept seeking fresh water.

ps. I have no clue what I'm talking about

by patates

6/6/2026 at 5:23:48 PM

It’s mostly that it takes energy. If fresh water is we drink that. There aren’t a lot of places where only salt water is available so, for most animals, it isn’t worth it to have evolved a way to extract water from salt water.

Animals in the ocean of course do live without fresh water. Some of them just live off of water extracted directly from their food or from metabolizing that food, which produces water. Some animals have specialized cells that excrete salt so that can take in salt water and separate out the salt.

by Tagbert

6/6/2026 at 5:18:06 PM

Salt water fish can process sea water, no point in evolving for saltier brine if you have oceans of 3% water.

by blackoil

6/5/2026 at 11:04:53 PM

Thermal methods require energy, it seems like this substrate is effective at maintaining its solar-thermal absorbing properties better than a material that will attract salts

> Testing their solar-thermal desalination technique using samples of water from the Pacific, Atlantic, and Indian Oceans, Guo and his team were able to make the surface self-cleaning. In other words, it extracted freshwater and directed the remaining salts to the passive region where they could be later collected without reducing the panel’s efficiency.

This is not "large" this is a moderate improvement. Albedo is likely only marginally affected, and the solar power input over area is the same.

Depending on this cost of this process it could very likely be a wash in terms of NPV

by otterdude

6/5/2026 at 7:28:04 PM

If this can be applied to mine effluent, you could replace the maybe with most certainly. Sulfuric acid effluent lakes leech all sorts of valuable metals out of the ground.

by CuriouslyC

6/6/2026 at 6:34:29 AM

Focusing on pure energy efficiency might be missing the point of economic efficiency.

An RO desalination plant needs electric energy to drive the pumps, which might be generated by panels which are 15-20% efficient. So, if you can have cheap thermal desalination panels, they come out ahead even if 6x less energy eficient, you avoid the whole expensive and fragile desalination plant and you gain a low skill, distributed setup.

by cornholio

6/6/2026 at 10:24:43 AM

This is valid for some use cases, but then it needs to be compared with other solar distillation methods, of which there are already a variety at different levels of energy efficiency, complexity, and land use.

by ajb

6/6/2026 at 2:18:33 PM

ScholarlyArticle: "Extreme salt-resisting multistage solar distillation with thermohaline convection" (2023) https://www.cell.com/joule/fulltext/S2542-4351(23)00360-4 .. https://scholar.google.com/scholar?cites=7551078272963689346...

"Desalination system could produce freshwater that is cheaper than tap water" (2023) https://www.eurekalert.org/news-releases/1002811

ScholarlyArticle: "Highly efficient and salt rejecting solar evaporation via a wick-free confined water layer" (2022) https://www.nature.com/articles/s41467-022-28457-8

"Solar-powered system offers a route to inexpensive desalination" (2022) https://news.mit.edu/2022/solar-desalination-system-inexpens...

by westurner

6/6/2026 at 4:22:15 PM

I remember the MIT press release. I wonder if they've found any commercial success.

by xhkkffbf

6/5/2026 at 7:28:26 PM

Brine is very easy to dispose of: you just pump it back to where it came from. Solid crystalline salt, on the other hand, is a hassle.

by xyzzyz

6/5/2026 at 7:49:50 PM

> Brine is very easy to dispose of: you just pump it back to where it came from.

Easy, but not necessarily good for the spot you're pumping concentrated salt back into.

by ceejayoz

6/5/2026 at 10:52:44 PM

If you use fat pipes that go a decent distance from shore, diluting your brine with ocean water, you’ll have a negligible impact on the ocean. The problem is if you dump lots of brine in shallow waters. Old designs did have that flaw, but it’s not that difficult to design around this constraint now that we know about it.

IMO this is an issue where NIMBYs are using environmental concerns as a smokescreen to block new desal plants from ruining the vibe at their beachfront property. Rhymes with the opposition against offshore wind farms.

by ashdksnndck

6/6/2026 at 1:58:10 PM

The city of Corpus Christi, TX is currently considering options for desalination plants—all of which pump their brine into the shallow water inside the bay or the ship channel.

by iamjs

6/6/2026 at 7:05:25 AM

> The problem is if you dump lots of brine in shallow waters. Old designs did have that flaw, but it’s not that difficult to design around this constraint now that we know about it.

I think that problem was known (and discarded as not important) when the first serious water desalination plants were built.

by Someone

6/6/2026 at 4:49:01 AM

I can probably be convinced pretty easily with some evidence of that, but you’ll never convince the contingent who is convinced it’ll kill sea life at any concentration or location, so, being able to shut them up by saying “we have no wastewater, we load rail cars with crunchy salt and use it for stuff” still has value.

by xp84

6/6/2026 at 4:02:50 PM

I wish we could reimagine carbon credits to that degree of stringency. You offset a kg of carbon emissions? Let's see that kg.

by __MatrixMan__

6/6/2026 at 7:09:48 AM

The goalposts will just shift to attack that excess salt instead. It’s like all of the FUD about datacenter water usage while people shove almonds in their mouths.

by kortilla

6/6/2026 at 11:17:27 AM

In Germany, it's the water usage of a Tesla plant vs. the neighboring asparagus farm.

by nkmnz

6/6/2026 at 3:20:17 AM

Yeah. Worrying about salt in the sea is like worrying about oxygen in the air. Can too much oxygen in the air sometimes be a problem? Yeah, in some corner cases. Is it a major problem that we can't solve? Not at all.

by FartyMcFarter

6/6/2026 at 8:31:05 AM

Isn't it more akin in this case to worrying about too much carbon dioxide in the air?

by 0xFF0123

6/6/2026 at 8:38:13 AM

Why is it akin to that? Doesn't the salt come from the sea in the first place?

by FartyMcFarter

6/6/2026 at 11:45:58 AM

A more apt comparison than you realize.

Most of the carbon we spew into the atmosphere came from the air. Ancient plants took it in via respiration.

by ceejayoz

6/6/2026 at 12:14:14 PM

That still doesn't make it a good comparison. The salt emitted by desalination plants is already in the sea now, it's not salt that went somewhere else.

by FartyMcFarter

6/6/2026 at 3:02:58 PM

And the water we take out eventually goes back.

by parineum

6/6/2026 at 6:17:41 AM

That makes sense to me. At the same time I know the mediterranean sea is heating up more because it cannot move heat out quick enough. I dont know of any mediterranean air, so I believe more closed water zones would behave different than, lets say, the atlantic ocean.

by mejutoco

6/6/2026 at 2:49:34 AM

[dead]

by eff-nix

6/6/2026 at 3:52:40 PM

Someone tell me why this is stupid, which it probably is: Put the desalination plant on a tanker ship and let it do its duty out in the middle of the ocean, then cruise back to port and dispense the water.

by analog31

6/5/2026 at 8:09:58 PM

The brine came from the ocean. So just dilute it back to close to ambient salinity using municipal waste water that you are discharging anyway.

by SoftTalker

6/5/2026 at 8:12:53 PM

> The brine came from the ocean.

Sure, and enriched uranium comes from the ground, but that doesn't mean it's safe to dump it back in after the enrichment process!

> So just dilute it back to close to ambient salinity using municipal waste water…

Wouldn't it generally be easier to process that municipal waste water, as is already fairly common?

by ceejayoz

6/5/2026 at 9:54:00 PM

> Sure, and enriched uranium comes from the ground

Uranium can also come from the ocean water (there is, apparently, quite a lot of it in there, relatively speaking). Japan experimented with the technology in the nineties, but it really was much cheaper to just mine it from the ground, so they abandoned it.

by Joker_vD

6/6/2026 at 6:53:52 AM

It's about 3 parts per billion. Uranium is about $85/pound, so you'd need to be able to completely process/extract about 40 million gallons of saltwater for $85 to break even. The real cost there is orders of magnitude higher. It's one reason the claim about the Earth having vast amounts of uranium is quite disingenuous. The amount of cost efficient accessible uranium is only enough to last ~1 century at current consumption rates. If nuclear energy scaled up significantly, we'd run out in a matter of decades if not less, or we send the price of uranium skyrocketing and the price arguments would need to be significantly adjusted.

by somenameforme

6/5/2026 at 10:56:12 PM

Japan is also barred from doing own enrichment, being a non-nuclear state. Though, there nevertheless is a dormant set of requisite facilities.

by numpad0

6/6/2026 at 2:48:48 AM

You're wrong. Japan does do their own enrichment, 150k SWUs at Rokkasho with plans to bring that up to 500k SWUs a year soon. If they chose to make.bombs instead of fuel, they could make dozens a year.

by redsocksfan45

6/6/2026 at 7:32:22 AM

That's the dormant plant. Rokkasho-mura plant is officially incomplete for decades, doing tests and upgrades without actual production.

If you think otherwise and you're not wrong, and I think you ARE not mistaken since this isn't the first time someone other than myself mentioned it here, that means they're making bombs because we in Japanese public aren't told about it. There has only been just some routine commentaries from local mayors at most.

by numpad0

6/6/2026 at 8:46:46 AM

I think you might be confusing the Rokkasho Reprocessing Plant (not yet operational, intended for plutonium extraction from spent fuel) and the Rokkasho Uranium Enrichment plant, which has been running at 75 tSWU/year (I think that should be kSWU or tSW) since 2023-08-24 https://www.jnfl.co.jp/ja/business/about/uran/daily/enrichme... 112.5 tSWU/year since 2025-06-26 https://www.jnfl.co.jp/ja/business/about/uran/daily/enrichme... and 150 tSWU/year since 2025-11-20 https://www.jnfl.co.jp/ja/business/about/uran/daily/enrichme...

It's a bit weird though that they have a graph of tons of uranium hexafluoride shipped that shows the last shipment in 2018 and nothing since then.

by yorwba

6/6/2026 at 11:59:45 AM

[dead]

by redsocksfan45

6/6/2026 at 2:42:59 AM

Enriched uranium is perfectly safe to dump but it would be stupid to do so. Fission products are nasty but uranium itself is not, comparatively.

by turkeyboi

6/5/2026 at 8:13:45 PM

The analogy would be if you "un-enrich" it. Then it's safe. Or at least no worse than when you took it out of the ground.

by SoftTalker

6/5/2026 at 8:14:35 PM

> The analogy would be if you "un-enrich" it.

But you're doing that with the same water you're trying to make in the first place!

by ceejayoz

6/5/2026 at 8:25:45 PM

You could just dilute it using fresh seawater, if you used enough and (maybe) spread it over a wider area. The amount of water people need for drinking is a relative drop in the ocean.

by SoftTalker

6/5/2026 at 8:34:23 PM

Brine doesn't necessarily behave the way you imagine.

https://en.wikipedia.org/wiki/Brinicle

https://en.wikipedia.org/wiki/Brine_pool

by ceejayoz

6/5/2026 at 8:52:21 PM

Blue Planet video of a brinicle, content warning for kind of horrifying death of sea creatures: https://www.youtube.com/watch?v=lAupJzH31tc

by jaggederest

6/6/2026 at 4:10:36 AM

And a Blue Planet II video of a brine pool, stronger content warning for much more horrifying death: https://www.youtube.com/watch?v=ZwuVpNYrKPY

by ianthehenry

6/5/2026 at 10:00:16 PM

You can dilute the brine in a facility before disposing.

by threwrfaway

6/5/2026 at 10:50:35 PM

Go on. With what?

by ceejayoz

6/6/2026 at 12:49:46 AM

Seems like you could just dilute it with seawater at like 100:1 ratio and it would be negligible done offshore. We already dump our shit 5 miles out.

by asdff

6/6/2026 at 2:01:39 AM

100:1 is overkill and energetically very wasteful. It's a fairly straightforward chemical engineering problem.

by threwrfaway

6/6/2026 at 1:54:04 AM

...sea water. You take 10 units of sea water for every unit processed and you'll get a slight increase in salinity.

A phase diagram tells you exactly how far you need to go.

You know this makes more thermodynamic sense than carbon capture, right?

by threwrfaway

6/6/2026 at 12:54:09 AM

gasoline

by pasquinelli

6/5/2026 at 11:27:54 PM

With fresh water, we’ll get it from desalinization! Hey wait a second…

by wlesieutre

6/6/2026 at 2:07:58 AM

Sarcasm aside, your comment actually works: you can use the freshwater from desalination!

Just wait for the saltwater to come back around in the sewer.

by threwrfaway

6/6/2026 at 3:12:17 AM

Globally about 70% of freshwater is used for agriculture so less than a third of it will come back around, if it's exclusively for residential/commercial use you might do better but overall not a strategy that balances out

by wlesieutre

6/6/2026 at 12:22:31 PM

70% of desalinated water wont ever go to agriculture because its too expensive to use for corn. Only very high value crops need apply.

But, so what? 30% sewage is still a strong dilluant... especially when mixed with more seawater

Im shocked how many people cannot grasp that you can dilute brine's salinity arbitrarily close to seawater's with energetically cheap pumps.

by threwrfaway

6/5/2026 at 8:25:01 PM

Municipal waste water is a much cheaper way to get desalinated water in the first place though.

by Enginerrrd

6/5/2026 at 8:40:19 PM

except for the pharmaceuticals anyway

by lazide

6/6/2026 at 3:28:49 PM

That’s been a solved problem, engineering-wise, for a while.

The advanced treatment stages take care of it. Between UV, ozone, and nanofiltration, etc. we can remove the pharmaceuticals.

Actually the problem is the water comes out too pure out of a well designed water reuse system, to the point where the mineral content can be too low and you need to add some back in.

by Enginerrrd

6/5/2026 at 11:20:13 PM

Hey, it's free viagra, prozac, progesterone and multivitamin supplements, all in a glass.

by shermantanktop

6/6/2026 at 5:00:12 AM

There’s some fat fish out there, I hope we can get those guys some Ozempic too

by xp84

6/6/2026 at 5:28:12 PM

Democrats intentionally killing the fishing industry by giving fish free glp1s and cocaine with your tax dollars!

by collingreen

6/6/2026 at 2:12:51 AM

Actually it's easy and ok. Just mix it with the treated sewage right before it returns. Simple mass action implies the salinity hasn't changed.

But wait! There's water mass loss due to leaky pipes and outdoor pools!

Mixing salt water and brine is perfectly ok. Just use a phase diagram.

by threwrfaway

6/5/2026 at 10:50:46 PM

Maybe, but dumping crystalline salt is even worse to the spot you’re dumping it on.

by xyzzyz

6/6/2026 at 12:51:31 AM

It doesn't need to be crystalline salt. Just mix the brine with seawater at a really high ratio of sea water to brine then dump that out. 100:1 ratio should be fine I would guess. Quick search suggests seawater salinity variance is already like 10%-15% or so. Even better if you pipe it offshore where currents will take it and not somewhere that doesn't circulate.

by asdff

6/6/2026 at 3:14:54 AM

Yes, that's my point: if you're next to the ocean, disposing of brine is extremely easy.

by xyzzyz

6/6/2026 at 3:32:59 AM

You could put it back into old salt mines.

by pajko

6/6/2026 at 3:48:45 AM

Even better, just package it up and eat it instead of digging underground and creating more pollution.

It's not every day that industrial waste happens to be not only edible but also tasty. Too tasty, in fact. Salt is addictive.

by kijin

6/6/2026 at 5:03:39 AM

It’s not going to be pure NaCl though; making Morton salt with it would make sense only if it wouldn’t cost more to process it (net of its resale value) than just disposing of it somewhere not particularly sensitive. I’d propose the Utah salt flats or indeed, kinda love the idea of just sticking them in a salt mine that is all tapped out. If it used to be chock full of salt it seems pretty environmentally fair to make it salty again.

by xp84

6/6/2026 at 9:05:52 AM

The impurities are exactly what give sea salt from various regions their distinctive flavors and mineral profiles. The salt should be edible as long as it wasn't pulled from seriously polluted waters. It might even sell for a premium.

by kijin

6/5/2026 at 10:58:31 PM

I wonder. It would have to dissolve, a big block of salt would take a while, kind of like the erosion of cliffs where the salt comes from in the first place. Eh, I guess you're right though, the fish wouldn't like that at all.

by card_zero

6/6/2026 at 12:42:46 PM

that's 200% bullshits. Countries that invested into desalination plants are known to create death zones right where brine is sent back - even if miles from the coast

by iberator

6/5/2026 at 8:03:56 PM

Why? Just build mountains out of it and maybe even open a salt-ski park in the tropics for people who don't have snow.

by qurren

6/6/2026 at 12:53:31 AM

There are salt mountains lining most midwestern freeways as it is for winter.

by asdff

6/6/2026 at 7:24:51 AM

Assuming my constants (35g/kg of salt in seawater, 650k tons of salt dumped by the state of ohio every year, 81 gallons per day of individual domestic water usage) are correct and my napkin math isn't completely buggered, and if we look at the salt as a primary product instead of just waste:

Ohio DOT's use of road salt would allow for fresh water to be provided for somewhere in the neighborhood of 160,000 people.

On one hand, that's nowhere near enough people; it's a small drop in a giant thirsty bucket of water consumption. So we'll still need salt mountains, salt re-distribution vessels, and/or other ways to deal with excess salt.

On the other hand, 160k is a lot of humans. So perhaps we should look into doing things like this anyway.

(But we probably won't. Ohio gets road salt primarily from a mine under Lake Erie that has a very conveniently-located terminus near downtown Cleveland. The mine directly loads trucks, freight trains, and ships...and it's near the point of use already. It's pretty efficient.)

by ssl-3

6/6/2026 at 5:05:37 AM

I just realized that future archaeologists will be tracing our roads using the salt residue!

by xp84

6/6/2026 at 12:14:15 PM

Actually I have been thinking about this. Surprisingly straight and long cuts in rock formations might be a real thing to track. In at least some places at least some rock blasting is preferred to get aggregate for road foundations. And these tends to be rather straight and rather steep.

by Ekaros

6/6/2026 at 9:31:02 AM

or just you know.. asphalt residue

by make3

6/5/2026 at 8:11:21 PM

I think I read somewhere that salt can be used as energy storage medium? So we could get both water and batteries for renewal energy.

by galaxyLogic

6/5/2026 at 10:58:42 PM

It’s about thermal storage, you don’t use table/sea salt for that, and you don’t need a lot of salt, because the salt is in a closed loop; it’s not being consumed.

by xyzzyz

6/5/2026 at 11:38:49 PM

But more thermal storage you want more salt you want, and it's gotta cost something, right?

https://en.wikipedia.org/wiki/Molten-salt_battery

by galaxyLogic

6/5/2026 at 11:48:48 PM

If you read the article you sent me, you'll learn that, just as I said, you don't use sodium chloride, aka table salt, aka sea salt, for these purposes.

by xyzzyz

6/6/2026 at 2:43:30 AM

A better example are sodium ion batteries, which are about to take off in a big way

https://www.catl.com/en/news/6812.html

by aeonfox

6/6/2026 at 3:13:21 PM

Oh no, the hassle of managing the raw input for several key industrial processes that is created for free as a side product of MAKING WATER DRINKABLE WITH FREE ENERGY FROM THE SUN is TOO MUCH OF A PROBLEM! Especially considering we could instead murder millions of fish - which we then can’t eat- in the process! This entire technology is doomed!

Come on guys please at least attempt to think what you’re about to type, please, I beg you.

by darksnart

6/5/2026 at 9:08:23 PM

> Solid crystalline salt, on the other hand, is a hassle.

Just put it on your fries.

by RobotToaster

6/5/2026 at 8:14:07 PM

In an ideal world that crystalline salt by product could be used to offset any imported or mined salt, further reducing the environmental impact of those operations.

by nkrisc

6/5/2026 at 7:46:29 PM

"Solid crystalline salt, on the other hand, is a hassle."

Just make prettier-than-Himalayan salt lamps out of it and sell it to hippies. Easy solution.

by lightedman

6/6/2026 at 12:06:04 PM

That only shifts the problem. Now we need an increased supply of hippies that are hard to come by in a low hippie-tolerant environment.

by rapnie

6/5/2026 at 10:36:50 PM

yeah, if you like to kill everything in a few 100 feet radius and kill some more in the zone of reliance.

this is delusional ecological

by cyanydeez

6/6/2026 at 5:08:37 AM

So, we could just dump it on the salt flats in Utah? Plenty of places are already super salty, so nothing lives there (unless it’s able to handle that).

by xp84

6/5/2026 at 10:54:48 PM

Brine might be bad to the place you dump into, but crystalline salt is even worse.

Overall though, it’s just such a tiny concern. Ocean is huge. If we kill everything in a 100 foot radius, that’s 0.0000000008% of the ocean being destroyed. Less than a drop in a bucket.

by xyzzyz

6/5/2026 at 9:29:58 PM

> My (limited) understanding is that conventional reverse osmosis is not far from the theoretical optimum, energy-wise, the main difficulties being operational (the membranes need declogging). And of course RO is more expensive than rain.

RO is about 2-4x the theoretical minimum, depending on how much water you're willing to reject.

by cyberax

6/6/2026 at 12:23:28 AM

[dead]

by aaron695

6/5/2026 at 6:46:24 PM

The paper: [1]

They're still at lab scale in glass. They haven't built a usable system, even a small one. The big claim here is that it doesn't clog; capillary action moves the salt out of the active area to another area, where some yet to be developed mechanism removes it. That needs to be demonstrated. If they can come up with something that runs for years without clogging or replacing the active material, that's a real advance.

Laser surface preparation is known.[2] It's useful for roughening smooth surfaces in a very structured way, in preparation for painting. The result is a smooth paint surface. If you sandblast to roughen, the first paint layer is somewhat irregular. Then you need to sand and paint again to get a smooth surface. Laser roughening has been tried for auto painting, but didn't go mainstream. A good question here is whether commercial laser surface prep systems can make the material this new process uses.

[1] https://www.nature.com/articles/s41377-026-02315-4

[2] https://www.youtube.com/watch?v=BKYOglHYo_Y

by Animats

6/5/2026 at 6:51:59 PM

It reminds me of how the Panama canal was built, and actually the first major attempt failed and they gave up. What they learned for the second attempt was that digging was not the hard(est) part to solve - it was how to move the dirt! So much dirt!

Great book on this BTW: Path Between the Seas. I couldn't put it down.

by Nifty3929

6/5/2026 at 8:12:59 PM

Fragility is a common problem in surface treatments, sometimes called "nanotechnology". There are super hydrophobic surface treatments that are very effective. They generate a surface which is a forest of tiny sharp points. The surface tension of water is too high to cling to such a surface. You can make something that just will not get wet. The problem is that the points are fragile, and wear destroys the effect.

Another example is ultra black coatings. Those are a forest of tiny black objects arranged so that light gets reflected multiple times and is absorbed. The commercial version is called "Vantablack". It doesn't wear well, but for optical applications such as the insides of camera lenses and telescopes, that's fine.

by Animats

6/5/2026 at 8:55:19 PM

It's such a good book! Like any dad reading history, I have been annoying my family for years with fun facts I learned in that book. David McCullough's other books like The Great Bridge (about building the Brooklyn Bridge) are also great.

by pchristensen

6/5/2026 at 11:44:45 PM

You and I are the same person apparently. Let me tell you about malaria! Or the bends! Or tetanus! Please! Wait, where's everybody going?

by Nifty3929

6/5/2026 at 7:59:05 PM

This is an interesting tech, but I have big doubts. In the picture you can see some salt coating the surface. Even just a little seems like too much for this type of system. I really hope they can make this work and scale this up.

by jmward01

6/6/2026 at 10:46:07 AM

This is similar to a MIT press release from 2023.[1] That's another passive solar powered desalinization system that supposedly doesn't clog with salt. The author's paper list has the 2023 paper, but no followup.[2]

Another MIT paper on desalination from 2024 has a more conventional electrically powered system that can adjust its operating speed depending on how much power is coming in. So it can run off intermittent power sources such as its own solar panels.[3] Rather than buffering the energy with batteries, just buffer the water in a tank. This made it to field test and has some efficiency numbers.

It's annoying to see these one-off announcements with no followup. A short note a year later reporting why there's no further work would be useful to later workers.

[1] https://news.mit.edu/2023/desalination-system-could-produce-...

[2] https://drl.mit.edu/publications/journal/

[3] https://www.greenmemag.com/science-technology/breakthrough-m...

by Animats

6/6/2026 at 1:52:37 PM

The crucial part is that pressure from the capillary action pushes the concentrated brine out onto the non capillary area. unlike fabric the area isn't enclosed so cleaning is easier if the salt starts to accumulate.

Obviously it needs to be cleaned regularly otherwise the salt encroaches into the sensitive bits. However the cleaning method doesn't require dissolving, just scraping.

by KaiserPro

6/5/2026 at 10:46:12 PM

>> The solar-powered system uses specially engineered black metal to absorb sunlight.

The new system replaces the earlier version that used specially engineered death metal.

by YeGoblynQueenne

6/6/2026 at 12:03:57 AM

Which was a big upgrade from the prior system which just used a heavy rock.

by BLKNSLVR

6/6/2026 at 11:15:52 AM

Which in turn was a huge upgrade from classical methods

by jpkw

6/5/2026 at 5:09:37 PM

This appears to be the same New Rochester article as 4 days ago with 20 comments.

https://news.ycombinator.com/item?id=48349507

by fhdkweig

6/5/2026 at 6:07:41 PM

Awesome, love seeing stuff out of Rochester - RIT or UofR or any of the nearby schools.

Totally underrated area for academic pursuits.

by b0rbb

6/5/2026 at 6:53:27 PM

Indeed, it’s the same university that gave us room temperature superconductors.

by haritha-j

6/6/2026 at 10:08:54 AM

Huh? That was University of Utah/Brigham Young University right. That is, if you're referring to Pons and Fleischman.

by SimplyUnknown

6/6/2026 at 10:32:35 AM

Pons and Fleischman was cold fusion. https://en.wikipedia.org/wiki/Cold_fusion

by eesmith

6/5/2026 at 6:49:13 PM

UofR physic grad that also worked at the LLE here. Agree Rochester schools are underrated (although admittedly a little biased).

At least in the sciences you have access to lots of opportunities you don’t have at bigger name schools.

They set me up in life in a way that I don’t think would have happened elsewhere.

by mmmBacon

6/6/2026 at 1:52:14 AM

I had a great time at UR in the early 90’s because they had the most computing hardware per interested student in the country. I was able to relatively quickly work my way up to access to pretty much any system the school owned that I wanted, including the Cray at the LLE.

by technothrasher

6/6/2026 at 2:40:35 AM

As an RIT alum, I tend to agree.

by block_dagger

6/5/2026 at 6:09:41 PM

Agree! Shout out to the Laboratory for Laser Energetics

by 0x59

6/5/2026 at 7:30:06 PM

RIT is pretty well known as a good school I believe.

by dyauspitr

6/6/2026 at 8:53:33 AM

I believe the most efficient method to turn "ocean water into drinking water" is called "rain". We just need to better collect and transport the output of what is effectively the world's biggest solar-powered desalinator.

by userbinator

6/6/2026 at 10:45:25 AM

Obviously this is region specific, but slowing down water is one of the best ways to have fresh water.

Slow it down from trickling down a slope and you have two things: more vegetation (which also retains water) and more time for that water to penetrate the ground for local wells.

You can completely "terraform" a desertic region https://youtube.com/shorts/cfhbtgon4Nk?is=oAExB5UeMAsShBux

by alex_duf

6/6/2026 at 10:43:18 AM

Let’s grab a giant pole and catch clouds. I wonder how much liter of water a giant cloud is. I also wonder what a good unit would be for a cloud. Small, medium and large is all I have

by mettamage

6/6/2026 at 9:27:24 AM

Well, sometimes it doesn't rain and (at least for coast regions) being able to desalinate can be of critical importance.

by Laurel1234

6/5/2026 at 6:53:57 PM

So crazy question: take a dehumidifier, attach some solar panels, and deploy at scale for non-potable water suitable for crop irrigation anywhere that isn't a desert. Does it work? And if not, why?

by LogicFailsMe

6/5/2026 at 10:40:21 PM

The short answer is all those problems have already been solved.

Israel desalinates 75-85% of its drinking water. The problem is political and economic dysfunction.

California for example could be doing widespread desalination with nuclear power and technology from the 1970s. They could also greatly expand reservoirs and waterways, but don’t do it. Very similar to Rome in the 400s, when people were using aqueducts built by a past civilization but lost the ability to construct them.

by oceanplexian

6/6/2026 at 3:04:13 PM

Nuclear is very expensive per MWh and thus per litre of water generated

Solar on the other hand is very cheap, and you don't need to desalinate 24/7 -- just do it when power is cheapest (which is during the sunny times if you have large amounts of solar, during windy if you have large amounts of wind, etc)

by iso1631

6/5/2026 at 7:12:16 PM

It takes too much energy and produces water too slowly to scale. In general any area with sufficient moisture in the air to explore this also has easier access to rain and ground water.

by LarsAlereon

6/6/2026 at 6:30:08 AM

A lot of energy is only a problem if that energy is very expensive.

The good news in a desert: plenty of sunshine. So you can generate a lot of electricity with some cheap solar panels, there is plenty of space to put some down, and there aren't a lot of NIMBYs around to complicate the permitting process for that.

Some desert ecosystems actually depend on condensation with specialized plants and animals harvesting humidity from ocean breeze. Large parts of e.g. the Sahara border on the Atlantic ocean. Lots of water in the air but not a lot of rain. And even if humidity is low, there still is some water in the air usually.

But the simple fact of course is that there is a lot more water in water than there is in air. If you want to extract meaningful amounts of water from air, you need to process a lot of it.

by jillesvangurp

6/5/2026 at 7:17:52 PM

Great point, in my case in the PNW, the water from my local well is infested with manganese (as in clogging the household plumbing in the absence of a sediment filter) and other contaminants and the water company providing it is owned by private equity. Legally, I can drill my own well for non-potable irrigation, but god forbid I filter and/or chlorinate it for my own household use. So I end up considering options like this, thanks for debunking.

by LogicFailsMe

6/5/2026 at 8:12:33 PM

You don't need to chlorinate water from your own well, unless maybe you have a cistern that you are filling for storage.

And who's going to know if you are drinking it or watering your garden?

by SoftTalker

6/5/2026 at 8:55:31 PM

At the very least I would UV disinfect anything coming from the ground and absolutely make use of a 20 micron sediment filter if only to address cognitive load: Another place, another time, coliform bacteria from the well. Super fun(not).

by LogicFailsMe

6/6/2026 at 5:28:24 AM

I vacillate between trusting my well and trusting my RO (10,5,1 micron filters, plus the membrane). But it isn't healthy to drink RO all the time and I don't wanna mess with remineralization.

My well is 100' and 13 years old.

by picofarad

6/6/2026 at 3:24:07 PM

For me I'd do a sediment filter and a charcoal filter and call it good. Send a sample out for analysis a few times a year.

by SoftTalker

6/6/2026 at 1:56:19 PM

Yield depends on humidity, which varies according to region and season.

It also requires more infrastructure to get yield. In theory all you'd need to have is these etched metal plates, a transparent dome and a source of briny water. (and a cleaning mechanism)

The etched plates creates 100% humidity (probably more as it'll condense out)

by KaiserPro

6/5/2026 at 7:07:37 PM

It "works" in the sense that this is what 99% of "Get water from air" scams are.

The reason it doesn't actually work is that it is extremely inefficient. Getting water to condense requires you to somehow reject massive quantities of heat. That's fundamental to physics.

Also, literally anywhere a dehumidifier is reasonably effective, is humid and usually doesn't have such dire water problems. Deserts have extremely low humidity and dehumidifiers working in a desert will produce very little water.

Even a good humidifier in a humid environment is burning KW to generate on the order of ten liters of water a day.

There are a couple places on earth that are essentially deserts but have an early morning humid fog roll through regularly, and those places figured out capturing that water in the air long long before we invented the refrigeration cycle.

It is literally cheaper to desalinate.

Maybe you could build giant greenhouses to fill with sea water and let the sun evaporate the water and collect that with a dehumidifier? Still absurdly inefficient. Water has such an obscene specific capacity for heat that any thermal avenue of separating it from something else will use immense energy.

by mrguyorama

6/5/2026 at 9:33:10 PM

The humid areas where they might work probably already have a lot of water?

by wagwang

6/5/2026 at 7:07:11 PM

What do you mean work? No, because there is no single dehumidifier on the market that will get you enough water, so you are out $80 grand, you could have just paid for water delivery.

by casey2

6/5/2026 at 9:09:56 PM

Always wondered why the coast of the Red Sea isn't littered with channels which get flooded with seawater, which then evpporate into glassed ceilings; creating freshwater, and leaving behind salts for mining.

Sand -> Glass -> heated saltwater -> freshwater + minerals -> ??? -> profit?

Combined with some mangrove farms, surely desert coasts are able to support more life.

Wonder if this is scalable tech, and how quickly it can 'process' water. I guess if they're combined with transparent solar panels, it could be quite an epic tech.

by gaiagraphia

6/5/2026 at 9:24:03 PM

Slightly different idea to take Red Sea water, concentrate it, and flow into the Dead Sea to stabilize the water level in the Dead Sea which is a big problem. A billion or so was spent but the project is on hold for some combination of financial, political and environmental issues.

https://en.wikipedia.org/wiki/Red_Sea%E2%80%93Dead_Sea_Water...

by dirt_like

6/5/2026 at 10:12:39 PM

I love projects like this. A shame the west has handed over the baton to the Chinese and Saudis when it comes to actually being daring with megaprojects.

Some over stuff whhich are cool to read about:

Redirecting Siberian rivers into Central Asia https://en.wikipedia.org/wiki/Northern_river_reversal

Redirecting Congo basin rivers to replenish Lake Chad https://en.wikipedia.org/wiki/Lake_Chad_replenishment_projec...

Filling in a depression in Egyptian Sahara desert and fllooding it with Mediterrraanean water to generate huuuuuuuuuuuuge hydro https://en.wikipedia.org/wiki/Qattara_Depression_Project

(Similar ideas proposed for Lake Eyre, the lakes in Tunisia, and the Afar Depression in Djibouti, too).

by gaiagraphia

6/6/2026 at 12:33:40 AM

The Saudis aren't "daring" with megaprojects. They're fucking[1] stupid[2]. Saying their megaprojects are "daring" is like saying I'm "daring" for claiming I'm going to build a catapult that will launch me to the moon.

[1] https://en.wikipedia.org/wiki/Trojena

[2] https://en.wikipedia.org/wiki/The_Line,_Saudi_Arabia

by AlexandrB

6/6/2026 at 12:36:24 AM

A comparison that only works if you say it and sink a few billion into foundations for said catapult.

by defrost

6/6/2026 at 7:44:51 AM

That’s what daring means. You try things that do not guarantee success. I remember a decade of people shitting on Dubai for all of the crazy projects it was building. It really paid off for them (pre Iran war). They made something out of nothing and still are. What’s stupid about a kilometer high tower? It’s fucking awesome.

by dyauspitr

6/5/2026 at 9:20:20 PM

If you've ever been to the beach, you can smell the salt air and rotting seaweed and hear the birds.

It's all gonna get on the glass (from above and below), and eventually the salt left behind is going to build up. The salt left behind is very hard on any structure or machinery used to move it which makes repairing the large glass enclosure a pain. All this for a slow trickle of water is generally not worth it.

by jrumbut

6/5/2026 at 10:06:52 PM

The Saudis were fucking around with the idea of solar domes at one point. Haven't heard anything about it for a while though (probably due to maths, lol). A shame, I've always been fascinated by Egypt and the empty expanses of nothingness. On long bus journeys around the country, the imagination can run wild.

https://www.solarwaterplc.com/featured-news/whats-inside-thi...

by gaiagraphia

6/6/2026 at 4:12:58 AM

The issue with that idea is very simple - creating those inlets into the desert would risk soil erosion - in the desert. If your objective was to desalinate water, you're much better off using conventional desalination (there's still way more room to work around here first, like better and sustainable membranes, etc.) and offsetting your emissions by locking carbon away in mangrove reserves, which are native to those desert coasts.

by fakedang

6/6/2026 at 3:16:12 AM

I am wondering if they combined photomolecular effect[1] to make it even more energy-efficient

[1] https://news.mit.edu/2024/how-light-can-vaporize-water-witho...

by iceboundrock

6/6/2026 at 6:55:42 AM

Distillation of H2O, where it loses an oxygen molecule and becomes H2, or gains a hydrogen molecule and becomes H2O2.

by biodiesel

6/5/2026 at 6:29:14 PM

They are talking about lithium recovery, but there is a less exotic byproduct I'm interested in. One tonne (≈ 1 m^3) of seawater contains about 1.3 kilograms of magnesium, equivalent to about 4 kg of magnesite ore. Typical desal prices are on the order of $1 per tonne. Magnesite ore goes for about $100 per tonne, so the crude magnesium in a tonne of seawater is worth about $0.40, which could account for a substantial fraction of the desalination cost. (These numbers are very rough.)

Now you ask: why don't we just recover magnesium from brines if it's so great? Magnesium recovery from seawater isn't that easy: typically you have to treat it with some kind of alkali (often Ca(OH)2), so the cost is dominated by the extraction process (your alkali is consumed!), and you're competing with a pretty cheap ore. But if you have a solid byproduct, instead of a liquid, the options for magnesium recovery might be a lot more efficient, potentially offsetting the cost.

The fourth-most-prevalent ion, sulfate, might also be interesting, at least in a hypothetical post-petroleum future where sulfur as a byproduct of fossil fuel extraction is no longer "free". Sulfate is also annoying to extract from seawater, but again if we have a solid, the rules change.

As for the "table" salt itself, I think we'd quickly saturate (!) the market.

by scythe

6/5/2026 at 8:59:39 PM

Calcining Mg(OH)₂ -which is what you find in seawater - converts the soft compound into magnesium oxide, a valuable mineral commonly used in refractories, catalysts, and ceramics.The Chemical Equation: $Mg(OH)_2 \xrightarrow{\Delta} MgO + H_2O$Temperature Requirements: You need to heat the magnesium hydroxide to a temperature range between 500°C and 900°C. Heating at the lower end (around 500°C) yields a highly reactive, porous form of nano-MgO, while heating above 1,200°C creates "dead-burned" MgO used in high-heat industrial bricks.The Yield: The weight of your final MgO product will be roughly 69% of the original Mg(OH)₂ mass, as the evaporated water accounts for the 31% weight difference. Already energy intensive. To get to magnesium ore is another step.

by cjbenedikt

6/6/2026 at 3:08:45 PM

> : $Mg(OH)_2 \xrightarrow{\Delta} MgO + H_2O$T

At least read what you're pasting

by iso1631

6/5/2026 at 11:11:59 PM

>Calcining Mg(OH)₂ -which is what you find in seawater

I'm not sure what to say, because it looks like you are copy-pasting from Wikipedia or something like that. Anyway, Mg(OH)2 is not found in seawater. Mg2+ is found as a dissociated ion. When you dry it, it mostly becomes MgCl2 with a little MgSO4. Mg(OH)2 is produced from seawater by the alkaline extraction process I mentioned before, and the process in TFA is interesting because it might be better.

Also, nobody would ever make magnesite ore. I referenced magnesium ore prices to estimate the value of the magnesium-as-ore in sea salt, because using finished magnesium prices would be misleading. Magnesium is mostly consumed either as the metal or as the oxide in cements and ceramics.

by scythe

6/5/2026 at 7:34:27 PM

After looking at the paper, this looks like the core result:

“We collected a total of 9.3 g freshwater along with 0.343 g of sea salt from the ABF-STIC with a 9 cm2 surface area over the course of 9 hours. This is equivalent to generating 10.33 liters m−2 of freshwater and 0.38 kg m−2 of sea salt per day. The salinity of the desalinated water is found well below the WHO and EPA standards for safe drinking water.”

However the enclosure system required looks rather complicated and might be sensitive to external temperature (maybe a solar PV-powered cooling loop would help) and I imagine the cost-per-square-meter of the material is rather high, so this looks more like something for emergency response situations or maybe a desal system for a mega-yacht. If it could be scaled the idea is interesting, maybe as lithium separation from concentrated geological brines?

by photochemsyn

6/6/2026 at 12:18:46 PM

This is a big deal for gulf states, another revenue stream in a the post-fossil world for them. Makes a transition more attractive for them.

by emsign

6/6/2026 at 12:45:34 AM

…but needs a specially engineered piece of metal…

by hofo

6/6/2026 at 3:21:03 PM

interesting read

by melonman2106

6/5/2026 at 8:09:40 PM

> The solar-powered system uses specially engineered black metal to absorb sunlight.

Brutal. 𖤐 \m/ 𖤐

by excalibur

6/5/2026 at 9:03:49 PM

If true then this might be indeed a game changer, but numerous academic publications turned out to be unfit for upscaling.

Who all has access to a femto laser? As far as I know these are all patented, and most of those patents (or at the least companies with rights to production) are in the USA, according to a professor who told us so some years ago in university (in central Europe, but he is quite old already, so I am not sure if his information was 100% up to date; but otherwise I do not doubt the validity of his claim made). So someone is going to milk rather than help. Will be interesting to see what happens to that in some years. My current guesstimate is that nothing will really happen or change.

by shevy-java

6/5/2026 at 6:55:10 PM

Probably some of the best news I've seen in a while.

by kogasa240p

6/5/2026 at 11:10:39 PM

I’m not even going to night clicking on a title that is clearly a load of bullshit.

I suppose you could water down the ocean water it’ll was drinkable, or like just add half a teaspoon of sea water to a cup or drinking water.

Buy all work done eventually decades in to waste heat.

by nandomrumber

6/5/2026 at 5:45:34 PM

> without waste

...except for the huge piles of salt.

If the salt was not waste, surely people would already be extracting it from the brine and the existing methods would also be "without waste".

by mkl

6/5/2026 at 5:51:04 PM

Persian Gulf has 20% more salt in water because of the humans which are throwing the oversalinated waste back into the sea. Dehidrated salt may be a big deal for some areas because of no waste into input.

by eimrine

6/5/2026 at 6:06:34 PM

>Persian Gulf has 20% more salt in water because of the humans

I would like to read more about this from an authoritative source.

by Jblx2

6/5/2026 at 6:28:07 PM

Through the magic of Googling "Persian Gulf salinity" it seems like it's more that it's a shallow Gulf in a dry area so it has significant evaporation. Desalination does effect it but it's only a few percent of the total evaporation (which is still surprisingly big) and doesn't sound like the main driving factor or an imminent ecological concern.

https://www.frontiersin.org/journals/marine-science/articles...

https://www.sciencedirect.com/science/article/abs/pii/S14635...

by tdb7893

6/6/2026 at 1:11:19 AM

Huh, looks like they process about 1/500 of the water in it every year. So enough to make a dent in the salinity eventually.

by card_zero

6/5/2026 at 8:51:28 PM

pardon my ignorance. But, all that salt was there already. right? Is it that we have less water there now ?

by MyHonestOpinon

6/6/2026 at 12:40:27 AM

If salt and water flow in but only water flows out you will be left with salt. Same reason that concentrated brine comes out of a desalination plant, or that the dead sea is what it is.

by fc417fc802

6/5/2026 at 6:59:12 PM

I thought the HN-way was to be more charitable than just directly calling out obvious bullshit.

by Jblx2

6/6/2026 at 12:05:32 AM

The brine is waste, and the dehydrated salt is also waste. Maybe dry waste is better, but it's still waste.

by mkl

6/6/2026 at 7:00:53 AM

Lavoisier’s “Traite elementaire de chimie” refers to water electrolysis.

by fsck400

6/6/2026 at 5:48:13 PM

[dead]

by napierzaza

6/5/2026 at 6:59:36 PM

Can we please ban university press releases

by fluorinerocket

6/5/2026 at 8:22:56 PM

why

by cush

6/6/2026 at 2:35:52 PM

I'll bite, I'll bite. But first ...

@GP: Instead of a plain complain, it's better to get an interesting discussion to write an explanation of why the post makes no sense, or instead find the good debunking comments and upvote them (there are two or three good comments near the top now).

I try to be that guy (personal hall of shame https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu... ) but life is too short and I have other things to do IRL.

Also, it's not my area. It's close enough to have a good guess, but in this case for me it's better to let someone else give an accurate reply.

---

Back to this post:

It obviously makes no sense. You have salt water, you extract the water, you have to get rid of the salt. Why waste time reading the details? [There are some interesting technical ideas about new surfaces, more on this later.] Reading the details their brilliant idea is to make salt cubes and sell them. So there is no waste!

When you get rid of the salt using brine, it's easier to transport and dilute the liquid. With solid salt you must scrape it form your high tech surface (without scratching it?!) and now the solid salt is difficult to transport. Also, to sell it you must purify it because it will include nasty things like crabs legs and sea smell.

Once you extracted the 99% of the water, it's difficult to extract the other 1% of the water because it's saturated solution with a low osmotic pressure, vapor pressure and a high boiling temperature. Also, water inside the block of salt is difficult to extract, and you must crush the small blocks.

Salt production is done in big salt lakes areas, where energy is "free". I like to consider it like a huge natural solar panel. You get heat for "free" and dry wind for "free". You must pay for them in an industrial facility. Also, the normal process still requires a lot of manual labor of guys/gals with [mechanical] shovels to makes piles of salt, wait, turn it a few times, wait, turn it a few times, wait, ... and you now have a nasty salt that you still have to purify to be able to sell it.

So they will get salt that is too expensive to sell, and too much of it to flood the market, and if you put it in the garbage can it will be classified as [industrial] waste.

---

The technical part looks interesting, but it's on the bottom of an unrealistic title and first paragraph. The interesting part is about the new surface with nano details and titanium oxide that absorbs Lithium. It sound interesting and they published it so there is some validation of the claim, but after the nonsensical first claims I'd want to take a look at the feasibility details.

---

>> Can we please ban university press releases

> Why?

I work in an university and I expect technical accuracy from the press department of an university. We want people to give us money in exchange of doing real and interesting things. We want people to trust the medical doctors when they give health advice, or a lot of other specialist about other public policies.

A lot of press release of the universities have a lot of exaggerations, burning the trust of the people. Before opening one here, I like to guess what is the real result and what is the bullshit part. I think that a complete ban of university press release here is too much, but I understand why the GP is annoyed.

by gus_massa

6/5/2026 at 5:40:26 PM

What about removing oil from water, have we conquered that yet?

by doublerabbit

6/5/2026 at 8:11:50 PM

you can now extract (like mining) minerals from the ocean, sounds kind of dangerous for the ecosystem maybe? making it profitable to extract magnesium, lithium, salt... we can probably guess how this story goes.

i'm hoping it doesn't scale, honestly.

by noripcord

6/6/2026 at 12:25:46 AM

You're wildly underestimating the scale of the ocean. If we could extract all our necessary minerals from it rather than mining them that would alleviate a huge cause of environmental damage.

by fc417fc802

6/5/2026 at 8:29:46 PM

You're worried we might use all the salt in the sea for some kind of ... salt pyramids, send the water back out through sewers, and consequently leave the world's oceans diluted? That's about 1 followed by 21 zeroes, I think, in liters.

by card_zero

6/5/2026 at 10:06:06 PM

no, just take the water, remove the salt & minerals. Over time it'll dilute. Water falls again in the form of rain, obviously, but not the salt.

You're not worried? If it's for batteries? For sure they'll extract whatever they can.

by noripcord

6/5/2026 at 10:33:00 PM

Right, remove the salt and minerals. We don't need that much salt, so we'd have to build pyramids or something with it. We drink the water, but then it ends up back in the oceans. The reason I mention that part is because if it didn't, if we could destroy the water, then the remaining water would retain the same salinity, and the concern would be that we drain the ocean dry, which is silly (I refer you back to how big it is). But we don't destroy water when we use it, so instead the worry is that we dilute all the world's ocean, which is also silly (I again refer you back to how big it is). We need a lot of batteries, but the sea is not useful as a source of lithium except as a byproduct. Even if it was the only source, the old batteries themselves would soon become a better source, as concentrated stores of lithium compared to the very-much-not-concentrated lithium in the ocean. But anyway the good places to mine lithium are on land (and are dried-up bits of ancient ocean, I think).

(I checked, some deposits are old lakebeds like https://en.wikipedia.org/wiki/Salar_de_Uyuni and others are igneous.)

It's also possible - true, I bet - that all the car batteries and storage batteries 8 billion people could possibly use are equivalent to only a tiny fraction of all the lithium in the ocean, but it would be harder arithmetic to confirm that, as well as being irrelevant on account of land-based mines existing.

by card_zero

6/6/2026 at 5:43:03 AM

Someone above said 4kg of magnesium per ton of seawater. Apparently lithium is 0.18g per ton of seawater.

That still means there's billions of tons of lithium in the seas, though.

by picofarad

6/5/2026 at 5:19:15 PM

This reads like hyperbole:

> The brine byproduct wreaks havoc on sea life when it’s deposited back into the ocean by raising the salt level and lowering oxygen in the water.

Managing return of concentrated brine should be entirely tractable in the literal ocean.

by kaonwarb

6/5/2026 at 5:23:35 PM

Sure, but typically desalination plants are located in a single physical place, so a discharge pipe dumping brine 24x7 is bad for all of the things around it, as the local concentration is extremely high.

by rconti

6/5/2026 at 5:29:13 PM

Seems like you could run a long perforated tube to diminish that effect.

by joshred

6/5/2026 at 5:39:23 PM

I wonder what the linear diffusion gradient would look like for that. Like the perforated garden hoses or whatever for soaking soil. Aquatic organisms grow so quick though very curious on the constraints for something like this.

by dieselgate

6/5/2026 at 5:33:39 PM

I liked the idea of loading it up on a ship that sails out releasing as it goes out and back. Make it solar powered or even go old school with literal sails.

by dylan604

6/5/2026 at 5:46:40 PM

I thought they tend to pipe far out and discharge as far below the surface as possible, since there is a lot of surface life and it is less damaging this way.

Ships (with long submerged pipes) would be prone to weather events and generally less reliable than an installed pipe. Perforation would be prone to clogging from build up so a nonstarter I would expect. Adding flex tubing and a relocation robot would be a maintenance headache as well. Not sure there is an easy optimization.

by sgc

6/5/2026 at 9:01:55 PM

Ships wouldn't need a long submerged pipe. It'd just need a small hole like a bilge drain or maybe a live well on a fishing boat. Just let the boat cruise around slowly draining back into the ocean.

As for surface life, I'm no oceanographer, but is that really the most vulnerable place? The surface is where fresh water rain meets the ocean, so that would dilute the salinity during storms. However, there's nothing to say that another pump couldn't be pulling from the ocean and mixing the brine into that so it's diluted before and not just pouring brine straight into the ocean

by dylan604

6/6/2026 at 4:51:35 AM

I think your sense of scale is off. 90% of sea life is on the surface. 0.029% of ocean water is replenished from rainfall annually. Desalination concentrates are absolutely toxic to life. The current daily volume of brine discharge would require more than half the tankers in the world to be filled and discharged every single day. They would of course not last long with such a routine.

by sgc

6/6/2026 at 2:02:39 PM

Is that a total for all of the oceans? I understand that as a whole, rainfall is literally but a drop in the ocean. However, confined just to the local area where the rain is falling, the area’s salinity has to change. Just like adding the the desalinated brine is a minuscule amount compared to the whole ocean, it has large effect locally.

Regardless, it is totally possible to reintroduce the brine back to the ocean in a way to not be a shock to the local area. We have just chosen to make it harder on ourselves for some illogical reason.

by dylan604

6/5/2026 at 6:05:52 PM

If you want to be really clever about it, maybe the ship is powered by the brine.

https://en.wikipedia.org/wiki/Osmotic_power

by scythe

6/5/2026 at 6:30:48 PM

I like this! Though I’m not sure the math works. That page says ideal efficiency for that system would be something like 0.75 kWh/m^3. Compared to 4000 to 5000 kWh/m^3 of diesel. Now we don’t need to be efficient since the point is to use up our “fuel” and we don’t need to cary cargo for this to make sense but with numbers like that, I don’t think our boat will be able to make enough power to move at all.

by gibspaulding

6/5/2026 at 5:31:34 PM

And it doesn't even need to be a rigid pipe. A flexible pipe made out of, say, waterproof fabric, could be cheaply made to extend miles while remaining open due to the pressure of the water pumped into it.

by 01100011

6/5/2026 at 5:34:14 PM

Things left underwater tend to collect things on it which would make this much less porous over time.

by dylan604

6/5/2026 at 10:06:26 PM

The short version is brine is weird: it's surprisingly resistant to diffusing and tends to flow more like an immisicible fluid. So you have to put quite a lot of effort into getting it to actually disperse rather then just fall to the seafloor.

by XorNot

6/6/2026 at 12:48:28 AM

That's silly, you'd mechanically mix it with seawater rather than wait for it to diffuse. The concern would be the volume of desalinated water extracted from the local region versus the flux from ocean current. As long as that ratio is acceptable there won't be any long term problem.

Alternatively, in the absence of sensible regulations a cutthroat operator devoid of ethics constructs a plant that dumps concentrated brine in the immediate vicinity because that's the cheapest approach. Then reactionary elements raise talking points about environmental damage and pretend that it's a difficult problem to solve. Business as usual.

by fc417fc802

6/6/2026 at 8:09:41 AM

Then they should become salt producers too. Win win (win).

by dizhn

6/5/2026 at 7:26:45 PM

The brine thing is just a way to shut down conversation and let people feel superior for claiming there are no solutions to our problems except to reduce our standard of living.

It’s obvious you can safely put salt back into the ocean with enough dilution. I bet a middle schooler could design a system to do it.

by bilsbie

6/6/2026 at 9:53:47 AM

Yeah, middle schooler with middle school understanding can design anything. There are plenty of middle school solutions in the comments around. The problem is when they meet real world, beyond their high school level understanding of the issue.

by rplnt

6/5/2026 at 6:26:11 PM

It kinda depends where it's deposited, right? The expected AMOC collapse is fundamentally about salt imbalance.

by gausswho

6/5/2026 at 5:25:39 PM

depends of course, how easy does the brine dissolve, how long does it take that it is so diluted that it can't do any harm, without that information it's not easy to tell

by wolfi1

6/5/2026 at 5:31:45 PM

These are often built near shallower parts along the coast where changes are more pronounced.

by dylan604

6/5/2026 at 6:04:27 PM

I mean.. we really want to permanently desalinate the ocean somewhat too so putting the brine back seems kinda stupid. Put it on land, let it dry, sell some as table salt and dump the rest into abandoned mines.

by boxed

6/5/2026 at 6:52:53 PM

Excellent idea! The largest abandoned mines I'm aware of are salt mines, which… hang on.

by wizzwizz4

6/6/2026 at 4:12:02 PM

Yea, that's one of the problems. We're literally digging up salt AND the mountains are being eroded to add more salt. The Earth is getting anti-terraformed and we're speeding it up. (Although obviously the fossil fuel situation is a much closer and worse problem)

by boxed