Desalination system could produce freshwater that is cheaper than tap water

Submitted ⁨⁨1⁩ ⁨year⁩ ago⁩ by ⁨Gsus4@feddit.nl⁩ to ⁨technology@lemmy.world⁩

https://news.mit.edu/2023/desalination-system-could-produce-freshwater-cheaper-0927

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.

www.cell.com/joule/…/S2542-4351(23)00360-4

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TurboDiesel@lemmy.world ⁨1⁩ ⁨year⁩ ago
Article doesn’t mention what the unit does with the salt waste.

I support this 100%, but desalination presents a unique problem: what do we do with all the salt? Maybe the unit uses it for something, but otherwise it just miniaturizes a problem that we’re already working on.

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- Gsus4@feddit.nl ⁨1⁩ ⁨year⁩ ago
  If this works, it’s better than anything we have , which costs grid energy and dumps brine all the same. If anything, the smaller scale makes it easier to distribute the brine dumping.
  
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  - TurboDiesel@lemmy.world ⁨1⁩ ⁨year⁩ ago
    If sea levels rise as much as they’re supposed to, this will be an invaluable tool for an enormous proportion of the country. My concern comes from capitalism getting its hooks into this.
    
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- MalReynolds@slrpnk.net ⁨1⁩ ⁨year⁩ ago
  Evaporate it to solid, store it if need be, or distribute it back into the sea in absorbable chunks. The water’s ending up back in the sea eventually anyway, see water cycle, so it should be zero sum, just need to avoid local overloads. Seems eminently solvable.
  
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  - Corkyskog@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
    Depending on the desalination method, you can also harvest lithium while your at it.
    
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  - DrM@feddit.de ⁨1⁩ ⁨year⁩ ago
    Sounds so easy for you but what to do with the excess salt is the only real problem with desalination that we have for decades now. It’s not easy to solve.
    
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  - topinambour_rex@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Eventually is an important word here. With the raise of temperature, the amount of vapor in the air raises too.
    
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  - FlyingSquid@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Increasing ocean salinity is a very bad idea.
    
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  - Nudding@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Hehe, adorable chunks…
    
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- Dewe@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Don’t you just dump it back in the sea? Diluting should make this a minor issue right?
  
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  - starman2112@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
    That’s what I always thought, but the local effects of hypersalinated water can be terrible for any nearby life
    
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  - assassin_aragorn@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Thats the big ecological question. If we do this at scale, we’ll be releasing more briny water back into the sea than we take. Over time on industrial scales, what will this do to the oceans? Is the increased salinity negligible, even at large scales? Or will it cause marine wildlife to die out?
    
    Think of it this way. Burning a pile of wood generates CO2. So first burning a bunch of gas or coal. A couple campfires won’t make a dent on the atmospheric composition. It’s only when we go this en masse and at industrial scales that we add appreciable CO2 to the atmosphere and cause global warming.
    
    The ideal way to handle desalination would be for us to use the salt that’s produced, so the concentration in the ocean remains unchanged with respect to desalination.
    
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- hydro033@kbin.social ⁨1⁩ ⁨year⁩ ago
  You put it back in the ocean. Laughable to think you would alter the ocean's salt content this way. All of the freshwater produced would eventually end up back in the ocean anyway.
  
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  - NaibofTabr@infosec.pub ⁨1⁩ ⁨year⁩ ago
    On the large scale this is true, but the problem is that the concentrated brine doesn’t instantly dilute back into the entire ocean. In large quantities, the waste outflow would damage the local coastal ecosystem before it was sufficiently diluted.
    
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- topinambour_rex@lemmy.world ⁨1⁩ ⁨year⁩ ago
  You cook with it.
  
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  - Obi@sopuli.xyz ⁨1⁩ ⁨year⁩ ago
    Fellow Frenchman detected.
    
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- assassin_aragorn@lemmy.world ⁨1⁩ ⁨year⁩ ago
  It’s able to successfully reject the salt waste, which is a success. The question will be if it can reject enough of it.
  
  The brine itself though is a really good question. I think there’s some existing uses for it, but we’d probably need to think of new applications for it as well.
  
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- DonnerWolfBach@feddit.de ⁨1⁩ ⁨year⁩ ago
  … can’t you just put i straight back into the sea?
  
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  - dgriffith@aussie.zone ⁨1⁩ ⁨year⁩ ago
    Suitcase sized device? Only one or two of them nearby? Then that’s not a problem.
    
    If you scale it to industrial sizes/quantities then the extra salinity in the area where you dump the waste products becomes an issue.
    
    Eg my coastal city uses about 135 megalitres of water a day. Supplying all that from seawater requires you to put about 5 metric tons of salt somewhere, every 24 hours.
    
    Stick 5 tons of salt a day directly in one place in shallow waters just offshore and you’ll end up with a dead zone a mile wide pretty quickly.
    
    So now you’ve got to water that salt down into something that’s only slightly saltier than usual and that can be difficult because for my example 135 million litres of water a day, you want to dilute the waste by at least 10x that (to make it approx 10 percent saltier) and now you’re cycling a billion-plus litres a day around the place.
    
    So this is pretty cool stuff, but just need to be careful with the side effects when it’s scaled up.
    
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- lefaucet@slrpnk.net ⁨1⁩ ⁨year⁩ ago
  I think the unit dumps it back into the surrounding water. I don’t think this will replace large scale reverse osmosis, but if it can produce enough for a couple people and not require external power, replacement filters, or frequent maintenance, then it’s has potential use for costal communities.
  
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- ColeSloth@discuss.tchncs.de ⁨1⁩ ⁨year⁩ ago
  Just toss it back out in the ocean or make lots of jerky.
  
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- scarabic@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Salt is an essential nutrient. We already make it from seawater just to get the salt! Now we’ll get some clean water as well.
  
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BeautifulMind@lemmy.world ⁨1⁩ ⁨year⁩ ago
This sounds fantastic on its face, but I seem to keep on hearing about how desalination will solve all kinds of problems and we still have this particular problem.

The missing piece, it seems, is the will for it to be used as infra at scale. Meanwhile selling bottled water taken for free from public lands for several dollars a liter in single-use bottles remains a multi-billion dollar industry. (an industry, I might add, that is aggressive about lobbying to protect its interests)

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- batmangrundies@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Devices like this are a lifeline for communities in developing nations. Who are the first and worst affected by water shortages and salt water intrusions into their fresh water sources.
  
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  - xenoclast@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Also the poorest and least likely to get the help from the people with the resources to help.
    
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- Astroturfed@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Not to mention if we do this at enough scale it will raise the salinity of the ocean and, you know, kill everything.
  
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  - ricecake@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
    That’s pretty unlikely, given that the water systems are more of less closed, and the volume of water in the oceans is so massive that it wouldn’t make an appreciable difference at any reasonable scale.
    Keep in mind that this isn’t the creation of desalination, just making it cheaper. There are already plants that do this at a scale of 50 million gallons a day, or under 1 trillionth of the oceans.
    
    Localized salinity changes are more likely to be an issue, but for that I think they just mix that salt back in with processed waste water, making it roughly neutral.
    
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  - BeautifulMind@lemmy.world ⁨1⁩ ⁨year⁩ ago
    
    will raise the salinity of the ocean
    
    If care isn’t taken to avoid concentrating brine going back in just one spot, sure that could create localized problems. Buuut, you realize that the oceans constantly lose water to evaporation and their salinity is more or less stable, right? Every bit of rain or snow that falls on land (most of which returns to the ocean eventually) is water the ocean can be without and still not too salty for life.
    
    Speaking of salinity, the Atlantic Meridional Overturning Current (which in normal conditions, is the deep/cold return current from the gulf stream -> North Atlantic) is running into a big damned problem because Greenland is melting and all that fresh water pouring off of it is disrupting the return flow of cold water to the tropics. That’s why the Gulf Stream has been so hot- it’s not getting return feed from its radiator in the North Atlantic, and meanwhile the North Atlantic is getting colder because it’s not cycling water back south, and that prevents hot Gulf Stream water from getting there.
    
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  - Smoogs@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Which also prevents ice from forming compounding more problems(the big massive problem) which we’re trying to avoid talking about right now.
    
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  - Tavarin@lemmy.ca ⁨1⁩ ⁨year⁩ ago
    The oceans have been collecting salt from runoff for billions of years, humans reintroducing some of that salt before the water will not affect ocean salinity.
    
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jcit878@lemmy.world ⁨1⁩ ⁨year⁩ ago
cool, but the real cost of desalination is transporting the desalinated water upstream, which presumably would also need to be done here

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- Hillock@kbin.social ⁨1⁩ ⁨year⁩ ago
  Considering how many people live near the coast it would still be a huge step forward. Right now even for most coastal cities desalination isn't cost effective and they have to import water from inland.
  
  And by not having to deliver as much water from inland to the coast that water can be distributed more for people living inland.
  
  Yes, it's not going to make inhospitable areas liveable but it's not just "cool".
  
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  - jcit878@lemmy.world ⁨1⁩ ⁨year⁩ ago
    the issue with water networks is they work great when you have the source (usually dams) upstream, water essentially is gravity fed throughout the network with only some localised pumping for certain elevated locations. wastewater again gravity fed towards treatment plants at the lowest point (usually the ocean), so usually, its fairly efficient, despite still requiring enormous amounts of energy.
    
    this doesnt solve that. it has the source where the end point is. the desalinated water needs to be pumped up, to then be gravity fed through the network. In some places, it is worth the cost and energy due to water scarcity, and im not knocking the technology. but claiming its cheaper than tap water is patently false because the distribution cost is far higher
    
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  - Spzi@lemm.ee ⁨1⁩ ⁨year⁩ ago
    A suitcase-sized, passive desalination device also sounds like a must-have for boats of all sizes, if they spend more than a few hours on sea.
    
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- Gsus4@feddit.nl ⁨1⁩ ⁨year⁩ ago
  True…otherwise it’s reverse hydro, which could be done with surplus renewables at peak times, but not at more than 10km… This is mostly aimed at coastal communities (and sustainable floating villages 😁)
  
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- Nougat@kbin.social ⁨1⁩ ⁨year⁩ ago
  Since this produces distilled water, I imagine you could use it to filter any water, not just saltwater. You'd still need to boil it to make sure it was free of pathogens, in either case, and add an appropriate amount of salts and minerals back in to make it potable for the long term.
  
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  - TheSaneWriter@lemmy.thesanewriter.com ⁨1⁩ ⁨year⁩ ago
    You're correct about readding a small amount of salts and minerals, but you may not actually need to boil it. Often the membranes used for distillation have pores that are so small that only individual atoms can go through them, which effectively filters out bacteria and virions.
    
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- DanglingFury@lemmy.world ⁨1⁩ ⁨year⁩ ago
  The other issue is localized oversalination of the remaining sea when you wash away the extracted salt
  
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BugleFingers@lemmy.world ⁨1⁩ ⁨year⁩ ago
SONOFABIT*H, I’ve been working on a project exactly like this with my friend for a couple years. Hella congrats they got it done and working first but damn :'( I was too slow.

Imma go sadly crush some bugles with my face stones now

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- surewhynotlem@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Keep doing it anyway. They still haven’t gotten to market, and I want choices when it comes to my post apocalyptic water suitcases.
  
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- guacupado@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Zero reason to stop. Until this is put into practice it’s just another article promising a future that isn’t here.
  
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- Spzi@lemm.ee ⁨1⁩ ⁨year⁩ ago
  Sounds like a great thing to include in your resume if you want them to hire you to keep working on it. Assuming theirs is better and succeeds.
  
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- assassin_aragorn@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Maybe you could contact them to do some joint work? If they’ve proven out the concept, the next step is scale up. And that’s a gigantic fucking step. I should think they’ll want people who are very familiar with the technology instead of people they have to train from the start. Alternatively, since this is in academia, you could work with them on commercializing it.
  
  You’ve got options! I think it’s probably wise to consider your next moves at this point, since they’d be likely to beat you to a patent :/.
  
  Good luck my friend, I’m rooting for you! And if I had more expertise in transient fluid and heat dynamics I’d offer some of my help.
  
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curiousaur@reddthat.com ⁨1⁩ ⁨year⁩ ago
All this stuff is like planning to colonize mars before we stop destroying earth. There is plenty of water if we just stop fucking pumping it all out and wasting it.

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- batmangrundies@lemmy.world ⁨1⁩ ⁨year⁩ ago
  We’re past the point where we can stop it wholesale.
  
  We already have aquifers barely holding on, we’ve lost major sources of fresh water already.
  
  I’m all for climate action, but we also need to starting developing technologies for living in the bed we’ve made.
  
  Folks keep talking about climate change like it’s some future event. You are living through it right now.
  
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  - orrk@lemmy.world ⁨1⁩ ⁨year⁩ ago
    you know how we can stop the massive drain on the aquifers? by not allowing everyone to tap it as much as they want, farmers will have to deal with 30% fewer yields on corn, Nestle 'n Co. will lose their money printer, but that’s all we would need to save the American aquifers, to STOP FARMING INT THE DESERT
    
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  - assassin_aragorn@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Yeah this is a very forward facing technology that may end up becoming a lifesaver.
    
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- DanglingFury@lemmy.world ⁨1⁩ ⁨year⁩ ago
  All farmers growing cotton in the middle of the fucking desert along the colorado river basin disagree with you
  
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  - SocialMediaRefugee@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Or how they destroyed the Aral sea for cotton
    
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- NOT_RICK@lemmy.world ⁨1⁩ ⁨year⁩ ago
  Clean freshwater isn’t evenly distributed across the world and it’s not easy or cheap to transport. This kind of tech can help the people that will be most impacted by climate change to survive.
  
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- Lucidlethargy@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
  Can you believe some people actually drink that stuff straight from the tap? It’s like they don’t even care about the golf courses at all!
  
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  - applejacks@lemmy.world ⁨1⁩ ⁨year⁩ ago
    why would anyone drink plain old boring water when you can get Mt. Dew from any gas station?
    
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Gerula@lemmy.world ⁨1⁩ ⁨year⁩ ago
Where’s the cheaper part?

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- Lucidlethargy@sh.itjust.works ⁨1⁩ ⁨year⁩ ago
  It’s just a giant plastic bag. They catch the runoff with a giant cup.
  
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  - jdeath@lemm.ee ⁨1⁩ ⁨year⁩ ago
    As soon as I saw the words “powered by the sun” in the synopsis, I knew what this was. I learned this during survival training, it’s a great way to turn piss (or any other undrinkable water) into clean water. And yeah, all you need is some plastic and a cup. Let the water evaporate (power of the sun) and collect the droplets in something. Had no idea that needed a science paper.
    
    Here’s the problem with desalination, tho: what do you do with the leftover super-brine? It’s pretty gnar stuff, like almost poison. Wide-scale desalination would produce tons of it every day. Most solutions i’ve heard are like “just dump it back in the ocean!” Which, yeah, how could that ever go wrong?
    
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  - Gerula@lemmy.world ⁨1⁩ ⁨year⁩ ago
    Exactly, imagine how much water can you gather in a hot climate that doesn’t evaporate untilyou get it or grow algae/fungi/protozoa/things that aren good for you.
    
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Tarastie@lemmy.world ⁨1⁩ ⁨year⁩ ago
Years ago they said that the screen lense from discarded projection TVs could boil/desalinate water with nothing but sunlight and discarded junk. They could literally create entire desalination plants with nothing but junkyard scrap. They never did anything with that.

I think all these “desalination” projects are nothing but worthless attempts to get free money for research

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- Spzi@lemm.ee ⁨1⁩ ⁨year⁩ ago
  What’s wrong with desalination research? Water is essential to life, and most water on Earth is salinated. The practical value of this research is apparent, both for ships on sea and coastal regions. So I don’t see how these attempts are “worthless”, and how it would be bad if they receive more “free money”.
  
  The article talks about what could have been a challenge faced by the junkyard scrap model, and how they solved it:
  
  Each stage contained an evaporator and a condenser that used heat from the sun to passively separate salt from incoming water. That design, which the team tested on the roof of an MIT building, efficiently converted the sun’s energy to evaporate water, which was then condensed into drinkable water. But the salt that was left over quickly accumulated as crystals that clogged the system after a few days. In a real-world setting, a user would have to place stages on a frequent basis, which would significantly increase the system’s overall cost.
  
  In a follow-up effort, they devised a solution with a similar layered configuration, this time with an added feature that helped to circulate the incoming water as well as any leftover salt. While this design prevented salt from settling and accumulating on the device, it desalinated water at a relatively low rate.
  
  In the latest iteration, the team believes it has landed on a design that achieves both a high water-production rate, and high salt rejection, meaning that the system can quickly and reliably produce drinking water for an extended period. The key to their new design is a combination of their two previous concepts: a multistage system of evaporators and condensers, that is also configured to boost the circulation of water — and salt — within each stage.
  
  I’m not sure how much money is in desalination, but it’s certainly an industry. If a group comes up with a new method, and then nothing happens with it, it’s probably because it’s either not that great after all, or not that cost effective.
  
  Maybe a problem is that the countries where it’s needed the most are not exactly the richest countries: ourworldindata.org/water-use-stress#what-share-of…
  
  several countries across the Middle East, North Africa & South Asia have extremely high levels of water stress. Many, such as Saudi Arabia, Egypt, United Arab Emirates, Syria, Pakistan, Libya have withdrawal rates well in excess of 100 percent — this means they are either extracting unsustainably from existing aquifer sources, or produce a large share of water from desalinisation.
  
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  - orrk@lemmy.world ⁨1⁩ ⁨year⁩ ago
    you know, if you build a large solar still, you just have to flush it every couple cycles to deal with the salt, and it can be as big as you can make a warehouse…
    
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- Edgelord_Of_Tomorrow@lemmy.world ⁨1⁩ ⁨year⁩ ago
  For desalination all you need is a glass bowl and two metal bowls. You put the bigger metal bowl on the ground, the smaller metal bowl in the middle, and the glass bowl over the little bowl. The salt water evaporates from the little bowl and condenses down the glass bowl into the bigger bowl. You can run this setup pretty much forever, there’s no moving parts and minimal maintenance. That’s how simple desalination is. All solar desalination projects work on this principle.
  
  The reason we don’t use it is the same reason we don’t do so many things: there is no immediate monetary cost to destroying the environment and using up common resources, so desalination is “expensive” compared to just using up the groundwater. Once all the groundwater is used up and the rivers run dry, desalination will be very competitive.
  
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MaroonMage@lemmy.world ⁨1⁩ ⁨year⁩ ago
I feel like every week we hear about some huge breakthrough that is supposed to revolutionize clean drinking water technology and save the world, but nothing ever comes of it.

I know this stuff takes time to develop, and not every idea is going to work, but it would be nice if one of these things actually did pan out and start being useful to solve our drinking water issues.

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- artic@lemmy.blahaj.zone ⁨1⁩ ⁨year⁩ ago
  solving issues isn’t profitable
  
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  - assassin_aragorn@lemmy.world ⁨1⁩ ⁨year⁩ ago
    It’s unfortunately not a profitability issue, at least not necessarily. I wish that it was, because then all you need is investors like silicon valley and you can run at a loss.
    
    What the researchers have created here is a bench top device. It needs to be scaled up for widespread commercial use, and that’s where things get difficult. Scale up is one of the things my field does, although I don’t have personal experience with it. Scale up is where a lot of projects die because of new issues developing.
    
    This device is relying on flow patterns and convection currents. That gives me some concern actually, because these patterns can change a lot with larger vessels. A common industry problem with fluid flow in larger tanks is that you’ll get “dead zones”. The internal flow dynamics are such that some parts of the vessel see no actual flow, and it’s just stagnant. That’s a big problem when you’re relying on flow to keep your entire tank cool or to carry out precipitated salts.
    
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- assassin_aragorn@lemmy.world ⁨1⁩ ⁨year⁩ ago
  It’s a matter of scale. You first try designs and concepts on a bench top scale in a lab. If that works, you scale the project up. And that scale up can reveal myriad problems. The internal heat and flow dynamics are going to change, and that may require a lot of adjustments. Specifically in this case, you may find that salt deposition is negligible at bench top scales, but when you start exploring larger units, salt ends up accumulating and causing issues. Scale up is part of the scientific process like any other, and it can end in failure unfortunately.
  
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Coreidan@lemmy.world ⁨1⁩ ⁨year⁩ ago
“Could”. What kind of fucking title is this?

Either it does or it doesn’t.

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- key@lemmy.keychat.org ⁨1⁩ ⁨year⁩ ago
  It’s a good title. They don’t know if it will be cheaper or not until they go and actually scale it up. Based on the prototype their projections say it should but it’s very likely they would run into issues that drive up the cost.
  
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- LesserAbe@lemmy.world ⁨1⁩ ⁨year⁩ ago
  They do say in the article that they haven’t scaled it up yet. If a large version works same as the small version it would do it. Hence “could”.
  
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aphonefriend@lemmy.world ⁨1⁩ ⁨year⁩ ago
Delete this before Nestle sees it.

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Smoogs@lemmy.world ⁨1⁩ ⁨year⁩ ago
‘Cheaper’….desalination eats a lot of power. This is causing a huge problem over a minor inconvenience.

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danielfgom@lemmy.world ⁨1⁩ ⁨year⁩ ago
We have destination where I live but the problem is this: the water often smells like fish. And it’s very hard because they use so many chemicals.

I don’t think desalination is the solution.

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