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

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.

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

> 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.

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.

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.

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.

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

Just put it on your fries.

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.

"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.

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

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.

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.

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...

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.

Which in turn was a huge upgrade from classical methods

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

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.

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)

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.

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.

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).

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...

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

At least read what you're pasting

>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.

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

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

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

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.

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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.

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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.

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>> 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.

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.

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

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

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.

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

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