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.

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

What, again?

>> 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.

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

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

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

Totally underrated area for academic pursuits.

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.

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?

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.

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...

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

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.

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?

…but needs a specially engineered piece of metal…

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.

interesting read

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

Brutal. 𖤐 \m/ 𖤐

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.

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

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.

> 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".

[dead]

Can we please ban university press releases

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

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.

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.