New solar desalination breakthrough makes fresh water without toxic brine | Hacker News Reader

New solar desalination breakthrough makes fresh water without toxic brine

sciencedaily.com

93 pointsrmason18 comments

I've wondered why desal hasn't also paired up with ocean mineral extraction. It seems like the two would go well together.

Even when talking about RO, you'd think diverting all or part of the brine water for evaporation would reduce the cost of extraction. You'd have water with more concentrated minerals which would give you a higher yield per evaporation cycle.

Also, it'd be nice if we could bring back magnesium extraction from ocean water.

Would like to see investment into removing dissolved co2, bicarbonate ion from the ocean as well.

What ever happened to that company that was going to extract materials for concrete from seawater?

No critical thinking at all in this article. So you take out the water and 50% of the lithium. You still haven't addressed what happens to the remaining NaCl, which was the main headline.

The headline should be "thing can extract lithium from sea water at 50% efficiency. It also produces potable water."

The potable water is the main product and lithium and other minerals are possible byproducts.

Assuming 55% extraction efficiency, the amount of lithium that can be produced is around 0.1 grams per ton of potable water.

Even by price, the lithium would bring less revenue than the potable water.

The amount of solid salt that this produces is many times less than the amount of liquid brine produced by other methods. Thus even storing it as waste is much simpler. Moreover, the salt may be useful for various purposes, even as table salt, assuming that the water had been properly filtered and treated before evaporation.

Well, salt may be less volume than brine. But the demand for table salt is pretty limited. Thus: Why pay for its disposal when you can discharge brine for free?

I think the idea is the salt is solid rather than in brine form. It can be sold as sea salt or whatever.

Original article:

https://www.rochester.edu/newscenter/what-is-desalination-de...

ScholarlyArticle:

"Additive-free and brine-discharge-free solar-thermal desalination with simultaneous complete mineral mining from ocean water" (2026) https://www.nature.com/articles/s41377-026-02315-4

I wonder what can have better potential efficiency, a classic solar panel and an electric boiler/dryer, or these devices?

Fundamentally, a direct device has fewer transformation losses.

Solar desalination looks pretty good in terms of efficiency. The problem is that the solar energy must now be collected at the shoreline. This means that a lot of coastal real estate gets turned into a desalination plant. Alternatively, you transport the water, but pumping seawater requires corrosion and fouling resistant materials throughout the system.

wouldnt something like UPVC/PVC/PEX not be good'nuff?

That is assuming your boiler uses resistive heating to generate heat and not heat pumps to move heat.

Why would you waste sunlight on light->electricity->heat conversion?

Just do direct evaporation like it's been done for thousands of years. If you don't like brine, leave it to dry out too.

If there is not enough sunlight, use direct nuclear heat.

Uranium is only 8 parts per billion so you may have some trouble sustaining a critical reaction with nuclear heat alone :)

Well, geothermal is basically it, so not very much trouble.

The method from TFA uses direct evaporation and it produces solid salt instead of liquid brine.

The innovation is that this can work as a continuous process, at a high production rate.

The traditional method requires waiting a lot of time until all the water evaporates, after which there is a long and expensive interruption, when you have to gather the salt and clean everything, to be able to fill again the installation with sea water and start another cycle.

Because of the high cost and low output rate, the traditional method is typically used only for the production of salt, not for the production of potable water.

For potable water, the currently used methods are mentioned in the article, and they produce a lot of liquid brine instead of a small quantity of solid salt, and that brine is difficult to dispose off.

From the article and their paper it is not clear how they intend to scrape the salt deposits from the untreated part of their panels.

If you ever tried to clean seasalt from your car or boat for example, it's not a trivial process and is best done by washing it away, which is counterproductive in this case. Mechanical scraping would likely either damage the panel or not clean it enough besides requiring moving parts which is costly.

So it remains to be seen if this is useful at large scale.

Reply on news.ycombinator.com