> In the meantime, the leftover salt continues to circulate through and out of the device, rather than accumulating and clogging the system.
I don't want to detract from the innovation of this, however my understanding is that one of the largest unsolved problems with desalination is what to do with the waste product: usually incredibly salty brackish water. Dumping it back into the ocean can be disruptive to the local ecosystem.
Is turning it into a solid too energy consuming? The main problem seems to have been it clogging up the multi stage system. If you can dump it you should be able to turn it into a solid in a separate setup.
Salt is very hydrophilic, I believe this means that it's very difficult to get the last bit of water out. Further, if you leave dry salt out in a humid environment and it naturally pulls humidity out of the air.
It collects on top though. Fleur de sel is made that way i believe. You arguably dont need to get all the water out of there as long as you have a steady stream of water with high salt content coming in.
Much of the price of that is coming from not breaking the formed patterns during harvest.
Most deserts are inhabited by endangered or threatened species. There aren't actually a lot of deserts so lifeless that you could avoid environmental activists getting in the way, at least not in the US.
US deserts are full of life; they're very far from lifeless. They're nothing like the endless sand dunes we envision when we think of the Sahara desert, Saudi Arabia, or the planet Arrakis.
The desert is far away. The ocean is much closer. Issues with increasing salinity go down drastically if you pump just a bit further into the ocean, where it is rapidly spread by currents. If that's considered too difficult/costly/energy demanding then pumping to a desert would be that much worse.
One possibility I have been thinking about is to locate desalination in an area with extreme tidal variation, particularly the northern Gulf of California (which coincidentally happens to be in a very thirsty region), where natural flows might be sufficient to disperse the brine. I have seen various studies talking about tidal currents dispersing brine but I haven't heard of any evidence that you can take advantage of highly tidal bays.
Everything we do affects the environment. Locally making the ocean a little bit saltier by removing water and not removing salt sounds like a very minor problem.
Seems like we could also just add it to the other places where water is flowing into the ocean. Do we not disrupt the ocean ecosystem with our fresh water runoff?
If you had a lot of fresh water runoff, you might use that fresh water for drinking rather than desalinating seawater though.
But... If you are using this water for drinking, it's going to come back through the sewage system, and maybe you can dilute the brine with outflows from local sewage treatment plants.
Depending on details, the combined outflow could be more or less salty than the seawater input to the desal plant.
Only some of it comes back through the sewage system. A lot of it just ends up lost to evaporation, or being incorporated into products. Think about your typical use of water to irrigate farmland (which is the majority use of water in many places); you don't really get any of that back as freshwater discharge at all. If you did, that means they're irrigating too much to the point that they're flooding their fields and causing runoff.
Sure, but do people really pay desal prices to irrigate fields?
Also, a lot of places are using desal to augment other supplies. If you've got 15% of your municipal water supply coming from desal, sewage treatment outflows should be significant compared to brine.
I haven't heard of any coral reefs at the Sea of Cortez, which is one place they're considering desalination, for Arizona (importing water from Mexico).
Edit: I checked and there are coral reefs along the Sea of Cortez. :) I don't know where would be safer to do it, but I'm sure it makes a difference where. And sadly it may not be as important at places where we've already destroyed the habitats.
The salinity is normally only increased by a factor of four (assuming a 25% reject ratio) so just be aware that brine discharge is a very highly localised environmental issue, it doesn't spread too far.
I wouldn't call it an unsolved problem necessarily. We probably disrupt the ecosystem more when we build a parking lot.
So, it's probably a good example then, since we currently accept the building of parking lots.
The point is, people are always writing letters to the editor and what-not when some green tech has some environmental impact, far more than they do over their city making another parking lot or any of a million other things. I assume it's because it triggers some notion of hypocrisy. c.f. wind turbines and dead birds.
How about we put our energy into fighting cars and parking lots first, before we worry about solar-powered desalination that could potentially save the Western states from the over-extraction of water that's turning them into dust bowls?
That's pretty cool. Personally, I'd prefer small roads and outdoor parking lots to be au naturel unpaved. Zero construction cost, and I imagine the maintenance cost is just trimming grass.
Only works if the natural soil is remarkably solid or the traffic negligible. Unpaved roads with more than very modest traffic generally need routine grading (repairing corrugations by scraping it over with a levelling blade) and re-graveling
Accurate. And, if there is significant rain and/or snowmelt, roads can quickly become impassable (see: "mud season" in New England, and surely many other places)
Carbon-based energy is socially acceptable, as are completely unsecured computing devices and mass corporate surveillance, but that isn't the standard of a good idea. If it was, we wouldn't want a forum like HN.
On a tangential note, I don't why paved outdoor parking lots are built[1]. It seems to be an entirely pointless exercise in aesthetics to me. I've parked on unpaved spots (in large parks near hiking trails, etc), and never had an issue.
We really should have more unpaved outdoor that is simply trimmed semi-regularly if or when the plant growth gets too big.
[1] Unless you're in a sandy or snowy area, where shoveling the sand or snow is difficult on an unpaved surface.
Unpaved parking lots tend to lose their plant growth when frequently used, after which the parking lot turns to mud in wet weather, which then results in stuck cars and dirt getting into stores with the customers that walked through that mud.
Pure soil wouldn't be a good option. Anything that's subject to high traffic, whether foot or vehicular, will also be subject to soil compaction which implies water pooling. That's a long way of saying those parking lots will turn into mud lots. At a minimum you could grade and gravel them, going the extra mile to crush the gravel so it stays in place longer. I do this with the driveway at my house because it rains a lot where I live. Paving would arguably last a lot longer and probably be more bang for my buck, but not having a place for water to go and having a basement is not a good combination.
On my driveway we only tend to get clovers and really resilient weeds. So, either really shallow rooted plants or weeds with absurdly strong roots. You're not likely to get native plans to grow unless you section off parts of the area for maintaining living soil.
To give a visceral example- There's an episode of Clarkson's Farm where the customers that parked in the grass at his farm shop need to get their cars pulled out of the mud by a tractor.
Just talking out my ass here, but can't it be combined with, say, treated wastewater?
We're taking the salt out of the water in order to "drink" it, but the reality is that most of it gets used for irrigation or toilets or whatever, and eventually returned either as groundwater or to the ocean.
Isn't the reject ratio typically closer to 75%? At least, my filter at home has a reject ratio of 75%, which means the wastewater is only ~33% more ppm than the starting water.
The salty sea water could even become the water to flush your toilet with as one use for the waste?!
I agree with the above, the scale of the proposed system shouldn't lead to sealife issues.
I don't think running saltwater through a toilet is straightforward. You would need higher quality parts, more frequent valve maintenance, and downstream waste processing equipped to handle the salt.
Sailboats use sea water in their toilets all the time but using it would require two systems, one fresh and another brackish. Very doable but more expensive. I believe they've also use grey water for toilets and plants but again it requires splitting the systems and having storage.
This plant helps Perth (a city of 2m people) get over half of its fresh water from desalination. We used to get most of our fresh water from the local aquifer and from dams, but this was totally unsustainable. The water table has been recovering over the past 10 years, and is on track to recover to pre-invasion levels in the next decade. By which time we should be at over 90% renewables for power too! Quite proud to be a West Australian really.
> Dumping it back into the ocean can be disruptive to the local ecosystem.
I question this as being a problem. The ocean is saturated with the salts that are exposed on the sea floor. When there is too much salt in a solution, the excess will precipitate as solids. As the ocean is already exposed to more salt than it can put into solution, I don't think this would cause a serious issue.
My controversial take is that the best solution will be to accept that solving the drinking water problem for people is worth worsening the environment for some local sea life.
A poorly implemented runoff would nuke a square km or five of ocean floor with high salinity waste. It would not impact food supply in any discernable way. The ocean is simply too big.
Further concentrated salt solutions deposit in the device, clogging it causing it to not work. You could harvest the salt, but then it is no longer passive.
> Or just sell it as salt? We use, I don’t know, billions of pounds of salt per year in food production?
Are you sure the math even remotely checks out? Just looking up some numbers, even if we naively assume ocean "saltwater" is just H2O + NaCl (which it obviously isn't): the world consumes around 300 billion kg salt/year, whereas (say) Los Angeles alone uses 700 billion kg water/year. So even if a city like LA provides for the whole world's use of salt, what does everyone else do?
I'm sorry, perhaps my engineering education makes me handwave at problems -- but the water we're desalinating has to return to the ocean someway, it's not like we throw it into black holes, why can't we just dump the brine 20 miles into the ocean, the water we've desalinated will return by other means.
You’re assuming we need to get 100% of our water from desalination when it would only need to cover any shortfall from other methods. We’re currently getting 100% of the water we need from those other methods.
Really depends who "we" is. Israel gets 75% of its water from desalination already, and that's just right now. And a lot of the other water sources right now are nonrenewable (groundwater, etc.), hence a big part of the motivation to look for new ones in the first place. The current situation is not sustainable on its own in many parts of the world, let alone the effects of dramatically increasing population sizes and global warming.
"Could have" is doing a lot of heavy lifting there. Assuming spherical cows, 12 is an upper limit, okay. What you could actually do is neither remotely close to that nor is that itself remotely close to what the world needs, was the point.
I don't think humanity is ever really considering environmental impact unless it impacts it somehow. We care about disappearing species which amuse us, which we can see at our scale level, not much below. Some rare lion? Tragedy! Thousands species of fungi living underground which don't impact us directly? Irrelevant. Same goes for climate change and others. We only care if it impacts us in any way, even if only our entertainment.
So long story short we probably care about sea life.
For the same reason we can't drink seawater: there is too much salt in it. The recommended water intake for a human is ~2kg, the recommended salt intake is ~2g. That's 0.2%, seawater has 1.5%. After you'd have eaten your share of salt, there is some leftover. You can't have someone else eat it, because then you'd also need more water. You could try to export it, but that requires quite a bit of extra processing, and the global demand for salt isn't high enough to pay for the transport costs.
This device is small-scale for individual families and small off-grid communities.
It's solar powered and passive. There's limitation on the salinity of the brine because you don't want to accumulate in the device. My impression is that this is not going to be a very big problem.
Until you notice that in some indirect way your life livelihood (or that of others in your community or some other actor with influence) does depend on that sea life. People are really quick to argue for the seemingly simple fix when interacting with complex systems. It rarely works out in the long term.
Source: climate change. It was really nice to emit a lot of carbon for a few decades, now it begins to cause real problems, conflicts and costs. Technical innovations should not simply assume that negative externalities are „fine“. Innovators should have to assume the burden of identifying and resolving the externalities before widespread distribution of the innovation.
> Innovators should have to assume the burden of identifying and resolving the externalities before widespread distribution of the innovation.
Based on what timescale, though? We can only work with what we know about. E.g. until Radium was deemed highly unsafe, it was deemed safe. No one paints Radium onto watch hands any more because we discovered that that's a terrible idea.
Or, it might turn out in 30 years that CO2 has a large positive effect on re-greening the Earth, and all those low CO2 innovations were harmful.
In other words: I don't understand how your statement makes sense without hindsight, and I don't understand how any innovation can happen if hindsight (that is based on that innovation happening) is its prerequisite.
> until Radium was deemed highly unsafe, it was deemed safe
You countered your own argument: Radium was never safe, it was just deemed safe because FAAFO was in fashion. Lead, Australian frogs, cigarettes, DDT, thalidomide, deforestation, and asbestos among (many) others have had lasting negative effects simply because we pushed ahead without considering whole-system complexity.
> because we pushed ahead without considering whole-system complexity
No, because we didn't know better. My argument was: how long do we wait til we decide we know better? Do we stop everything? How long is long enough?
You're talking as though right now many things we think are the best thing to do won't turn out to be a terrible idea. They will be, because there is no way to consider "whole-system complexity" on a long enough time period to do things completely safely, or even to do anything at all, as anything might turn out to be a bad idea on a long enough timescale.
> how long do we wait til we decide we know better? Do we stop everything? How long is long enough?
I agree with your premise and not with the threshold.
To make an analogy: you give a kid a bike and only teach them balance as they ride it.
Someone who has a “nothing can hurt me” mentality will jump on, go down hills, jump through bushes, etc. It’s most likely that they would break bones and possible that they die before learning what they need to know to be safe (enough).
Someone who has an overcautious mentality may try to fully understand the physics of bike riding before venturing past the lawn. It’s likely they won’t get hurt at all and it’s possible that they simply never ride outside the yard.
In my opinion, both are negative outcomes.
However: if someone is of the right mentality they will experiment safely, seek to understand enough of the physics to know the dangers, and take on challenges that are appropriate for their level. They will probably get hurt and might even break a bone but they will be able to recover and keep riding.
In my opinion, if we put genuine care and attention in to thinking about system complexity before/as we progress we can avoid many of the “obvious” problems without having to stop everything. I agree that there’s no way to avoid all potential fallout, but I think we can stay with consequences we can recover from if we accept that it means seeing ourselves as a part of a much bigger picture.
After lithium extraction, there's still a brine with roughly the same salt concentration, but likely with more other pollutants. You'd just be kicking the problem down the road.
But the issue is dumping the brine into the ocean as the only economical way to deal with it. If someone can make a significant profit off the brine, it may be feasible to truck it to a lithium facility then deal with disposal in a way that isn't just "dump it in the ocean and pretend it's not a problem".
Basically before releasing it back mix it with sea water at 1:10 or 1:100 ratio and it should not make that much of a difference. And make the outlet pipe quite far away from the inlet directly into a current if possible so it will mix with the rest of the sea.
There is a plan made by Israel and Jordan to bring water from the red sea to a desalination plant, and dump the leftover in the dead sea, it's like the perfect solution
Yeah this is one of my concerns, too: what impact on on the oceans will this have? Maybe the salt can be used in electric car batteries somehow? What impact if any would desalination have on oncean water levels? If the process makes for water cheaper than at the tap what’s to stop industrial users?
You're using solar energy to separate the saltwater from freshwater. You're not going to gain any more energy than that from mixing them back again, so this idea is just solar with extra steps.
I grew up in a city that was once an important part of the salt trade routes to Bohemia. These routes were called "Goldener Steig" (golden path), and salt was considered "white gold". Entire wars were fought for salt. And now it's so abundant, that we're sitting on mountains of it, not knowing what to do with it. Thinking about that feels kinda unreal.
Looking at the comments, I'm baffled by the number of people that still think it's "minor issue" while doing absolutely no research.
It's not just a little bit of salt, it's enough to kill fishes and whole ecosystem at scale, and it's all in the quoted article that people have definitely not read.
It's actually only a challenge in shallow water that doesn't move, which if you think about it isn't that surprising. If you pump it out a bit further, you quite literally have a whole ocean to dilute the salt in. Off the coast of California, for example, which is a state that should have no water shortage as it has abundant access to clean solar and wind energy and the entire pacific to desalinate, ocean depths drop quickly even just a few miles out. You would not be able to affect salinity levels of ocean waters there in any measurable way even if you wanted to.
So, the solution is pipes and pumps. Those add cost of course but it's a completely solvable problem otherwise. Exhausting natural sources of ground water and aquifers also has an impact. Desalination done right might give some of those stressed ecosystems a chance to recover.
> It's actually only a challenge in shallow water that doesn't move, which if you think about it isn't that surprising. If you pump it out a bit further, you quite literally have a whole ocean to dilute the salt in.
What do the studies say what the effects of stripping water from the oceans and increasig the concentration of salt and other things are?
Yea, but it's different. For example, we have harmed ecosystems by our flood, erosion, etc. control of rivers. They're supposed to move, but we don't let them, and that has detrimental downstream, figuratively and literally, effects. And it's because we view rivers as just a vessel or tract of water rather than as part of a system. Analogously, the ocean is not just a bucket of water.
Coastal ecosystems are particularly sensitive and are already at a tipping point. Are they meant to have bits of it pumped out, filtered, and everything but the water dumped back in?
I have been downvoted here, but is it really a bad thing to attempt to understand things a bit better? Before we solve one problem by creating another problem, something humans are really good at?
The brine more often than not contains traces of pretreatment chemicals, heavy metals, and other byproducts. It's frequently treated before being disposed of. Methods include pumping it down to the ocean floor or mixing with a source of less salty (wastewater/hydro) runoff. Removing the trace chemicals to make salt out of the brine would be prohibitively expensive.
Sorry for the extremely ignorant comment: but can't salt be solidified and stored somewhere as waste? and then maybe sold as food or for industrial uses?
Surely it would be more efficient than salt pans or mining salt as we do today...
My understanding is that this system is meant to be used at a small and distributed scale, not at an industrial scale like city-level desalination plants. In that case, it shouldn't be a big issue.
So could it be behind this dead zone? ''The largest such dead zone in the world is in the Gulf of Oman, a strait bordered by Iran, Pakistan, Oman, and the UAE. It occupies a whopping 165,000 square kilometres of the water body, an area bigger than even the state of Tamil Nadu (130,060 square kilometres). https://nyuad.nyu.edu/en/news/latest-news/science-and-techno...
I don't know anything but how about putting it in a hole ?
What would be the consequences of that ? (Sure there are plenty but I am too dumb to think of any)
The flush tank of my toilet was leaking. I called a plumber, and the first thing he did was to scoop up more than 2 handful of salt solids from the flush tank and clean it well - I wasn't aware that our community uses untreated hard water for toilets. And I was shocked, as I wasn't aware this happened, at the amount of left over salt that had accumulated!
Salt is a by-product of desalination and, as I understand, not easy to dispose without affecting the ecology of the area where it is disposed (let's not forget that salting of fields was done as an act of warfare against the enemy to make their lands barren, and then there's the natural Dead Sea - https://en.wikipedia.org/wiki/Dead_Sea - that exists and highlights what happens to marine life when water has too much salt content in it). Unless salt waste disposal is solved, desalination isn't going to become popular.
Wouldn’t the rising sea levels more than counter any salt being returned to the sea, as long as it’s dumped far out enough? Won’t climate change cause the concentration of salt in seawater to go down?
Even if the water produced by this process is like distilled water(without the minerals needed for drinking water), if it is cheap enough, and scalable enough, countries like India, Arab countries and northern African countries could theoretically pump in such clean water into the ground and mix it with the little fresh water they have in their land…
Setup the system to produce a 100 million liters per day, and pumping into ground inland should still replenish the ground water levels enough while earth does its thing to add the needed minerals…
Heck use such water to plant trees where it would not have been possible otherwise…
This. It may seem like wishful thinking, but the problem of desertification is so immense that we ought to approach any potential remedy with first principles and determine feasibility.
Could passive desalination be a way to bootstrap local ecosystems in arid environments to a degree where it would be self-sustaining?
Tap water has to come from somewhere. Dig a well, dam a river or desal the ocean, they all have significant costs to produce, treat, and distribute the water.
Even if you did build one of these devices outside your house, you'd still need to pressurize and plumb it into your house's water supply.
Simply producing water is but one step among many to make that water usable.
I think it is time for internets to adopt a second heading/headline. It can explain what the article is about like in the good old days, the first one can bait the clicks. We all want better click bait but also to know wtf is going on. "It produces unlimited FREE drinking water!" => "remove salt residue from solar distillation apparatus"
I think we've got another one at Alkimos that supplies another 15% or so right? I think we are projected to have the majority of our drinking water come from desal over the next few decades.
Desal is cheap as chips compared to Water Corp's supply charge!
And it’s a pretty recent thing too since we realised we couldn’t just blindly drain the underground water and the rain had become insufficient for our long term population growth predictions.
Water and food are the absolute essentials to life. If meta came up with a new product, you can ignore it, but you cannot ignore water scarcity.
Most nations are beginning to deal with intense water pressure issues. Especially as seasons don't follow the patterns so perfectly. A flash drought could cripple almost all water and excessive underground water pumping sinks the land. See china's issue with random potholes due since the land is sinking.
Modern water desalination is quite new, so technology has much room to grow. Not only does that make it attractive in terms of patents for better systems, but also there's always a market.
Yeah, but they would do much better if they had a legal system protecting there internal inventors and geniuses from party corruption and harmony idiocy. Nothing new can be introduced harmonious
I think if you did it at that scale it might flood the market and push the price down. You might be able to trade it to areas with a legitimate need, but you'd be competing against the people who just scoop it from ancient seabeds with a bulldozer.
considering that 6 months ago, 3 lbs of salt was sold for $2.29 (pnw, Oregon) and now sells for that for a single lb, that might be ok to flood the market and lower the price. if it can be disposed of for that price.
shrinkflation sucks, it doesn't mean we need to be beholden to it.
The price is already just about as low as it's reasonably going to go, with the price being dominated by factors unrelated to the actual production of the salt. Your average person consumes under ten grams of salt per day. The market simply isn't that large, and it's easy to make it in bulk at those scales.
* labor (no, price for labor hasn't increased 3 fold)
* transport (no, the price for transport hasn't increased 3 fold)
... still looking for an explanation why prices would increase 3x, and allow the packaging to be redesigned to be 1/3 of the size but with new plastic (as opposed to cardboard/recycled) and be sold at the same price.
if you can lower the cost of the original product, shouldn't you also be able to avoid some shrinkflation/redesign/platicification?
It might mean a 3x increase in margins for the producer or reseller, as has been the case for a lot of the price increases seen after the pandemic.
Or, most realistically, it's a combination of all of these - some increase in labor and transport prices, some increase in the producer's margins and some in the reseller's. Not to mention various other intermediaries taking their own cuts.
But sea salt hasn't gone up 3X in price. You have to look at actual market rates, not the arbitrary price being charged by one single store that's raising prices because they can (and which they'll do for any product). Searching right now, I'm seeing around $0.60/lb for bulk sea salt, e.g.: https://www.webstaurantstore.com/regal-salt-sea-fine-25/1020... And note that it might be cheaper still from a local supplier if you go pick it up in person.
Or, to put it a different way, the responsibility is on you as a consumer to actually get the best price on whatever you're shopping for. Some retailers can raise the price arbitrarily high, but you don't need to fall for it.
Purified, crystalized, brand-name, food-grade salt, delivered to my doorstep, is about $3/pound. Demand for that is pretty limited - how much more salt would you use, if you could buy it for only $1.50/pound?
Vs. this device produces "concentrated seawater" - which still contains every bit of algae, fish poop, plastic pollution, etc. that was in the original seawater.
Looking at this as a 'black box', You have the heat resource of the sun that will heat all the water. Let us say 10% evaporates and condenses into the storage area, the remainder is now 3.5% salt plus .35% saltier and it maintains it's heat. If you allow 10% to exit and be replaced with cold 3.5% salt water, AND it exits via a counter current heat exchanger = heat stored is kept, the added .35% salt is a minor effluent and will disperse. The greatest problem is the propagation of algae and suspended sea life that will soon proliferate to clog all surfaces, with free floaters exiting as well. Any salt/fresh water aquarist will know that this will be a problem. The system will work until the algae problem(not to speak of clam/mussel/barnacle etc larvae that are ubiquitous in sea water.
I would look and see if they have tried to patent the system. I'm unable to search anything immediately, but patents and followed by licensing to the associated startups are bare minimum steps that needs to happen to have any confidence that the system can pan out in real life.
It's a weird comparison, but no if desalinated water is being delivered to taps you'd expect deslinated water to be cheaper than tap-water, if you take the price at the source instead of the price after a (not free) delivery process.
I agree that's what OP is saying, I'm saying that's not true. The "is" operator here isn't commutative, "tap water is desalinated water" is true, but "desalinated water is tap water" is not.
Let's put some numbers to it. Assume tap water is desalinated, it costs $1 to desalinate a unit of water, and $1 to deliver a unit of water to taps. Then tap water is going to cost $2 while desalinated water only costs $1. Delivery to taps isn't free, so if you just want to buy bulk desalinated water it's cheaper.
Only innovating on price, not on dealing with the toxic brine dumped into the shores (ocean shores are a bio-diverse eco-system in itself, that you can't find in the rest of the ocean).
What if you dump the brine 10 miles into the ocean via pipes?
The desalinated water has to make its way back to the ocean somehow, I would not be worried about us making an impact on the Earths ocean salt levels, and if we dump the brine far enough into the oceam, there must be cubic power laws about salt dissipation.
I wonder if this is not done because it's expensive (maybe brine corrosion requires expensive pipes), or because governments will simply do nothing until there is public outcry (unlikely to happen in Saudi Arabia, they would need international pressure).
Or just dump the brine on the ground in a dump site. Let the water seep away underground and the salt pile up to eventually be bulldozed away from the pipe outlet when it gets too high.
I'm picturing something that looks like mine tailings.
Possibly the stuff could be sold as pavement salt for cold climate markets. Depends on how dirty it is I suppose.
Price is the only barrier to desalination. Environmental impact is a problem to be solved, but we never try to solve it for other things, so why for this?
And people were actually doing large scale desalinated water at least 20 years before that, because it’s a pretty well known solution - why do you need to bring up Musk?
Musk has been talking for five years about a topic that's been discussed in depth everywhere for the past twenty years and your conclusion is what exactly?
> In the meantime, the leftover salt continues to circulate through and out of the device, rather than accumulating and clogging the system.
I don't want to detract from the innovation of this, however my understanding is that one of the largest unsolved problems with desalination is what to do with the waste product: usually incredibly salty brackish water. Dumping it back into the ocean can be disruptive to the local ecosystem.
A quick search turned up this Scientific American article about the issue: https://www.scientificamerican.com/article/slaking-the-world...
"The excess salt decreases dissolved oxygen in the water, suffocating animals on the seafloor"
"In addition to harming sea life, extreme salinity also makes desalinating the water more difficult and expensive."
Is turning it into a solid too energy consuming? The main problem seems to have been it clogging up the multi stage system. If you can dump it you should be able to turn it into a solid in a separate setup.
Salt is very hydrophilic, I believe this means that it's very difficult to get the last bit of water out. Further, if you leave dry salt out in a humid environment and it naturally pulls humidity out of the air.
It collects on top though. Fleur de sel is made that way i believe. You arguably dont need to get all the water out of there as long as you have a steady stream of water with high salt content coming in.
Much of the price of that is coming from not breaking the formed patterns during harvest.
Pour it out in the desert?
Most deserts are inhabited by endangered or threatened species. There aren't actually a lot of deserts so lifeless that you could avoid environmental activists getting in the way, at least not in the US.
US deserts are full of life; they're very far from lifeless. They're nothing like the endless sand dunes we envision when we think of the Sahara desert, Saudi Arabia, or the planet Arrakis.
The desert is far away. The ocean is much closer. Issues with increasing salinity go down drastically if you pump just a bit further into the ocean, where it is rapidly spread by currents. If that's considered too difficult/costly/energy demanding then pumping to a desert would be that much worse.
That kind of desert : https://en.m.wikipedia.org/wiki/Salar_de_Uyuni
Ed Staffords Into The Unknown visits salt harvesting sites in the Danakil Desert in Ethiopia in case somebody wants some more insights into this.
edit: Or here Aljazeera https://www.youtube.com/watch?v=PgDiW2ELx7k
One possibility I have been thinking about is to locate desalination in an area with extreme tidal variation, particularly the northern Gulf of California (which coincidentally happens to be in a very thirsty region), where natural flows might be sufficient to disperse the brine. I have seen various studies talking about tidal currents dispersing brine but I haven't heard of any evidence that you can take advantage of highly tidal bays.
Everything we do affects the environment. Locally making the ocean a little bit saltier by removing water and not removing salt sounds like a very minor problem.
Seems like we could also just add it to the other places where water is flowing into the ocean. Do we not disrupt the ocean ecosystem with our fresh water runoff?
Freshwater runoff is normal. The continents and the sky dump freshwater into the oceans constantly at very high volumes.
If you had a lot of fresh water runoff, you might use that fresh water for drinking rather than desalinating seawater though.
But... If you are using this water for drinking, it's going to come back through the sewage system, and maybe you can dilute the brine with outflows from local sewage treatment plants.
Depending on details, the combined outflow could be more or less salty than the seawater input to the desal plant.
Only some of it comes back through the sewage system. A lot of it just ends up lost to evaporation, or being incorporated into products. Think about your typical use of water to irrigate farmland (which is the majority use of water in many places); you don't really get any of that back as freshwater discharge at all. If you did, that means they're irrigating too much to the point that they're flooding their fields and causing runoff.
Sure, but do people really pay desal prices to irrigate fields?
Also, a lot of places are using desal to augment other supplies. If you've got 15% of your municipal water supply coming from desal, sewage treatment outflows should be significant compared to brine.
I mean, they do if they're watering their lawns and that's where their water is coming from.
I think the answer is that it depends where.
I haven't heard of any coral reefs at the Sea of Cortez, which is one place they're considering desalination, for Arizona (importing water from Mexico).
Edit: I checked and there are coral reefs along the Sea of Cortez. :) I don't know where would be safer to do it, but I'm sure it makes a difference where. And sadly it may not be as important at places where we've already destroyed the habitats.
Edit 2: Some are very concerned about its potential effect on Sea of Cortez: https://tucson.com/opinion/local/local-opinion-desalinating-...
The salinity is normally only increased by a factor of four (assuming a 25% reject ratio) so just be aware that brine discharge is a very highly localised environmental issue, it doesn't spread too far.
I wouldn't call it an unsolved problem necessarily. We probably disrupt the ecosystem more when we build a parking lot.
That's not a great example - surface parking lots and their runoff are fucking horrible for the environment
So, it's probably a good example then, since we currently accept the building of parking lots.
The point is, people are always writing letters to the editor and what-not when some green tech has some environmental impact, far more than they do over their city making another parking lot or any of a million other things. I assume it's because it triggers some notion of hypocrisy. c.f. wind turbines and dead birds.
How about we put our energy into fighting cars and parking lots first, before we worry about solar-powered desalination that could potentially save the Western states from the over-extraction of water that's turning them into dust bowls?
I'm not going to lose any sleep over that. Permeable concrete exists, but it's just not worth the maintenance cost in most places
https://en.m.wikipedia.org/wiki/Pervious_concrete
That's pretty cool. Personally, I'd prefer small roads and outdoor parking lots to be au naturel unpaved. Zero construction cost, and I imagine the maintenance cost is just trimming grass.
Only works if the natural soil is remarkably solid or the traffic negligible. Unpaved roads with more than very modest traffic generally need routine grading (repairing corrugations by scraping it over with a levelling blade) and re-graveling
Accurate. And, if there is significant rain and/or snowmelt, roads can quickly become impassable (see: "mud season" in New England, and surely many other places)
Won't they become unusable when it rains?
It's a good example then. Given that a Walmart parking lot is societally acceptable, fresh clean drinking water probably will be too.
Carbon-based energy is socially acceptable, as are completely unsecured computing devices and mass corporate surveillance, but that isn't the standard of a good idea. If it was, we wouldn't want a forum like HN.
What's the problem with parking lots?
"Fucking horrible" is unquantifiable. Policy decisions need to be based on figures.
Unfortunately, in reality many policy decisions are based on enough many people thinking X is "fucking horrible".
On a tangential note, I don't why paved outdoor parking lots are built[1]. It seems to be an entirely pointless exercise in aesthetics to me. I've parked on unpaved spots (in large parks near hiking trails, etc), and never had an issue.
We really should have more unpaved outdoor that is simply trimmed semi-regularly if or when the plant growth gets too big.
[1] Unless you're in a sandy or snowy area, where shoveling the sand or snow is difficult on an unpaved surface.
Unpaved parking lots tend to lose their plant growth when frequently used, after which the parking lot turns to mud in wet weather, which then results in stuck cars and dirt getting into stores with the customers that walked through that mud.
Pure soil wouldn't be a good option. Anything that's subject to high traffic, whether foot or vehicular, will also be subject to soil compaction which implies water pooling. That's a long way of saying those parking lots will turn into mud lots. At a minimum you could grade and gravel them, going the extra mile to crush the gravel so it stays in place longer. I do this with the driveway at my house because it rains a lot where I live. Paving would arguably last a lot longer and probably be more bang for my buck, but not having a place for water to go and having a basement is not a good combination.
On my driveway we only tend to get clovers and really resilient weeds. So, either really shallow rooted plants or weeds with absurdly strong roots. You're not likely to get native plans to grow unless you section off parts of the area for maintaining living soil.
To give a visceral example- There's an episode of Clarkson's Farm where the customers that parked in the grass at his farm shop need to get their cars pulled out of the mud by a tractor.
Just talking out my ass here, but can't it be combined with, say, treated wastewater?
We're taking the salt out of the water in order to "drink" it, but the reality is that most of it gets used for irrigation or toilets or whatever, and eventually returned either as groundwater or to the ocean.
In some cases, yes. I know we had a temp desalination running here for a while, and they just mixed the brine with sewerage outflow.
Obviously it depends on the location of the sewerage outflow relative to the location of the plant.
Of course this only matters at scale. For the suitcase sized device mentioned in the article the amount of brine generated is negligible.
It may be better to just treat the waste water and skip the desalination in that case.
Isn't the reject ratio typically closer to 75%? At least, my filter at home has a reject ratio of 75%, which means the wastewater is only ~33% more ppm than the starting water.
Yeah that'll be right for a small scale unit, I think it's just that large commercial-scale RO plants have better reject ratios.
The salty sea water could even become the water to flush your toilet with as one use for the waste?! I agree with the above, the scale of the proposed system shouldn't lead to sealife issues.
I don't think running saltwater through a toilet is straightforward. You would need higher quality parts, more frequent valve maintenance, and downstream waste processing equipped to handle the salt.
Just as a reference, 80% of toilets in Hong Kong are flushed with seawater: https://en.wikipedia.org/wiki/Water_supply_and_sanitation_in...
Sailboats use sea water in their toilets all the time but using it would require two systems, one fresh and another brackish. Very doable but more expensive. I believe they've also use grey water for toilets and plants but again it requires splitting the systems and having storage.
Check out the pictures of the brine discharge diffuser at this desal plant in Western Australia: https://www.watercorporation.com.au/Our-water/Desalination/P...
This plant helps Perth (a city of 2m people) get over half of its fresh water from desalination. We used to get most of our fresh water from the local aquifer and from dams, but this was totally unsustainable. The water table has been recovering over the past 10 years, and is on track to recover to pre-invasion levels in the next decade. By which time we should be at over 90% renewables for power too! Quite proud to be a West Australian really.
> Dumping it back into the ocean can be disruptive to the local ecosystem.
I question this as being a problem. The ocean is saturated with the salts that are exposed on the sea floor. When there is too much salt in a solution, the excess will precipitate as solids. As the ocean is already exposed to more salt than it can put into solution, I don't think this would cause a serious issue.
This is not true.
https://en.wikipedia.org/wiki/List_of_bodies_of_water_by_sal...
> As the ocean is already exposed to more salt than it can put into solution ...
Haven't heard of that before. Wouldn't it mean there are underwater areas carpeted in salt crystals?
It's been demonstrated as an actual problem with currently functioning desalinization operations.
My controversial take is that the best solution will be to accept that solving the drinking water problem for people is worth worsening the environment for some local sea life.
That local sea life also provides humans with food. So even with the human-centric viewpoint, we have a strong incentive to solve this problem.
A poorly implemented runoff would nuke a square km or five of ocean floor with high salinity waste. It would not impact food supply in any discernable way. The ocean is simply too big.
Which ocean? People used to think this about raw sewage discharge. Check the state of UK beaches
That's impacting people who want to swim or surf in the sea. It's not impacting food supplies. Fishing boats operate much farther out.
Did so in person a couple of weekends ago. Looked fine, don't know what you're talking about.
> poorly implemented runoff would nuke a square km or five of ocean floor with high salinity waste.
So what is the problem then? We only need to lay pipes to ocean floors that are already not that lively?
Well no, that does not describe the local sea life everywhere.
Why does that have to be the solution?
Why not further concentrate it through evaporation? Then take that and pour it into old salt mines or spent oil wells? Or natural gas wells?
can we just pile it up into a huge salt mountain? and maybe eat some of it?
Further concentrated salt solutions deposit in the device, clogging it causing it to not work. You could harvest the salt, but then it is no longer passive.
Then don't concentrate it on the devices. Dump the water on a drying pool and extract the salt afterwards.
Ironically we'd probably need some amount of water to then purify the salt from the other random stuff
Need distilled water, luckily we were just making that.
You are underestimating the volume.
In that volume, you need a large drying pool.. which is no better than a parking lot.
Or just sell it as salt? We use, I don’t know, billions of pounds of salt per year in food production?
Making usable salt takes quite a bit of doing but as you note, we are already doing it.
I ran into this, it seems to explain how the sausage is made:
https://iopscience.iop.org/article/10.1088/1742-6596/1968/1/...
> Or just sell it as salt? We use, I don’t know, billions of pounds of salt per year in food production?
Are you sure the math even remotely checks out? Just looking up some numbers, even if we naively assume ocean "saltwater" is just H2O + NaCl (which it obviously isn't): the world consumes around 300 billion kg salt/year, whereas (say) Los Angeles alone uses 700 billion kg water/year. So even if a city like LA provides for the whole world's use of salt, what does everyone else do?
I'm sorry, perhaps my engineering education makes me handwave at problems -- but the water we're desalinating has to return to the ocean someway, it's not like we throw it into black holes, why can't we just dump the brine 20 miles into the ocean, the water we've desalinated will return by other means.
You’re assuming we need to get 100% of our water from desalination when it would only need to cover any shortfall from other methods. We’re currently getting 100% of the water we need from those other methods.
Really depends who "we" is. Israel gets 75% of its water from desalination already, and that's just right now. And a lot of the other water sources right now are nonrenewable (groundwater, etc.), hence a big part of the motivation to look for new ones in the first place. The current situation is not sustainable on its own in many parts of the world, let alone the effects of dramatically increasing population sizes and global warming.
According to a quick Google search,
> On average, about 35 g of salt is present in each 1 kg of seawater
so if those 700 billion kg of water for LA all came from desalination, that would yield 24.5 billion kg of salt.
That suggests we could have 12 LA-sized cities relying entirely on desalination before we'd saturate the world's demand for salt.
> That suggests we could have
"Could have" is doing a lot of heavy lifting there. Assuming spherical cows, 12 is an upper limit, okay. What you could actually do is neither remotely close to that nor is that itself remotely close to what the world needs, was the point.
The demand for salt is already saturated. It's a mature worldwide industry.
Adding your 12 cities would double the supply.
Salt filled with micro/nanoplastics.
I don't think humanity is ever really considering environmental impact unless it impacts it somehow. We care about disappearing species which amuse us, which we can see at our scale level, not much below. Some rare lion? Tragedy! Thousands species of fungi living underground which don't impact us directly? Irrelevant. Same goes for climate change and others. We only care if it impacts us in any way, even if only our entertainment.
So long story short we probably care about sea life.
Why can’t we just eat it?
For the same reason we can't drink seawater: there is too much salt in it. The recommended water intake for a human is ~2kg, the recommended salt intake is ~2g. That's 0.2%, seawater has 1.5%. After you'd have eaten your share of salt, there is some leftover. You can't have someone else eat it, because then you'd also need more water. You could try to export it, but that requires quite a bit of extra processing, and the global demand for salt isn't high enough to pay for the transport costs.
2g/2kg = 0.1% not 0.2%
And seawater has ~3.5% salt content by weight, not 1.5%
This device is small-scale for individual families and small off-grid communities. It's solar powered and passive. There's limitation on the salinity of the brine because you don't want to accumulate in the device. My impression is that this is not going to be a very big problem.
There are always trade offs.
As someone who has essentially unlimited access to clean drinking water, I might not feel the trade off is worth it.
But if I was someone who didn’t have a superabundant supply of clean drinkable water, I’d probably say to hell with the sea life.
Until you notice that in some indirect way your life livelihood (or that of others in your community or some other actor with influence) does depend on that sea life. People are really quick to argue for the seemingly simple fix when interacting with complex systems. It rarely works out in the long term.
> It rarely works out in the long term.
How've you determined this?
Source: climate change. It was really nice to emit a lot of carbon for a few decades, now it begins to cause real problems, conflicts and costs. Technical innovations should not simply assume that negative externalities are „fine“. Innovators should have to assume the burden of identifying and resolving the externalities before widespread distribution of the innovation.
> Innovators should have to assume the burden of identifying and resolving the externalities before widespread distribution of the innovation.
Based on what timescale, though? We can only work with what we know about. E.g. until Radium was deemed highly unsafe, it was deemed safe. No one paints Radium onto watch hands any more because we discovered that that's a terrible idea.
Or, it might turn out in 30 years that CO2 has a large positive effect on re-greening the Earth, and all those low CO2 innovations were harmful.
In other words: I don't understand how your statement makes sense without hindsight, and I don't understand how any innovation can happen if hindsight (that is based on that innovation happening) is its prerequisite.
> until Radium was deemed highly unsafe, it was deemed safe
You countered your own argument: Radium was never safe, it was just deemed safe because FAAFO was in fashion. Lead, Australian frogs, cigarettes, DDT, thalidomide, deforestation, and asbestos among (many) others have had lasting negative effects simply because we pushed ahead without considering whole-system complexity.
> because we pushed ahead without considering whole-system complexity
No, because we didn't know better. My argument was: how long do we wait til we decide we know better? Do we stop everything? How long is long enough?
You're talking as though right now many things we think are the best thing to do won't turn out to be a terrible idea. They will be, because there is no way to consider "whole-system complexity" on a long enough time period to do things completely safely, or even to do anything at all, as anything might turn out to be a bad idea on a long enough timescale.
> how long do we wait til we decide we know better? Do we stop everything? How long is long enough?
I agree with your premise and not with the threshold.
To make an analogy: you give a kid a bike and only teach them balance as they ride it.
Someone who has a “nothing can hurt me” mentality will jump on, go down hills, jump through bushes, etc. It’s most likely that they would break bones and possible that they die before learning what they need to know to be safe (enough).
Someone who has an overcautious mentality may try to fully understand the physics of bike riding before venturing past the lawn. It’s likely they won’t get hurt at all and it’s possible that they simply never ride outside the yard.
In my opinion, both are negative outcomes.
However: if someone is of the right mentality they will experiment safely, seek to understand enough of the physics to know the dangers, and take on challenges that are appropriate for their level. They will probably get hurt and might even break a bone but they will be able to recover and keep riding.
In my opinion, if we put genuine care and attention in to thinking about system complexity before/as we progress we can avoid many of the “obvious” problems without having to stop everything. I agree that there’s no way to avoid all potential fallout, but I think we can stay with consequences we can recover from if we accept that it means seeing ourselves as a part of a much bigger picture.
Why not sell the brine for lithium extraction?
After lithium extraction, there's still a brine with roughly the same salt concentration, but likely with more other pollutants. You'd just be kicking the problem down the road.
But the issue is dumping the brine into the ocean as the only economical way to deal with it. If someone can make a significant profit off the brine, it may be feasible to truck it to a lithium facility then deal with disposal in a way that isn't just "dump it in the ocean and pretend it's not a problem".
Can’t you just dilute it with more sea water?
Basically before releasing it back mix it with sea water at 1:10 or 1:100 ratio and it should not make that much of a difference. And make the outlet pipe quite far away from the inlet directly into a current if possible so it will mix with the rest of the sea.
Dump it in the great salt lake in Utah
There is a plan made by Israel and Jordan to bring water from the red sea to a desalination plant, and dump the leftover in the dead sea, it's like the perfect solution
Thanks for posting a substantive examination of the issue. The first engineering question always is, I wonder how the tradeoffs can be reduced?
Let's try that before jumping to popular political positions of ridicule and dismissal.
Easy, evaporate it in a salt lake and use or store the resulting salt.
Yeah this is one of my concerns, too: what impact on on the oceans will this have? Maybe the salt can be used in electric car batteries somehow? What impact if any would desalination have on oncean water levels? If the process makes for water cheaper than at the tap what’s to stop industrial users?
The water ends up in the ocean again one way or another.
As water with different salinity levels mixes entropy increases, so you can gain energy. You could build a power plant around the water mixing:
https://www.bbc.com/future/article/20150610-blue-energy-how-...
You're using solar energy to separate the saltwater from freshwater. You're not going to gain any more energy than that from mixing them back again, so this idea is just solar with extra steps.
The extra step being the gain of freshwater
Make bricks!
https://nocamels.com/2022/11/bricks-made-of-salt-the-buildin...
presentation on the screen is in comic sans. serious?
I grew up in a city that was once an important part of the salt trade routes to Bohemia. These routes were called "Goldener Steig" (golden path), and salt was considered "white gold". Entire wars were fought for salt. And now it's so abundant, that we're sitting on mountains of it, not knowing what to do with it. Thinking about that feels kinda unreal.
Looking at the comments, I'm baffled by the number of people that still think it's "minor issue" while doing absolutely no research.
It's not just a little bit of salt, it's enough to kill fishes and whole ecosystem at scale, and it's all in the quoted article that people have definitely not read.
A "whole ecosystem" could mean a 2 square meter area or a 500 square km area. The article doesn't really specify how big of an issue it really is.
It's actually only a challenge in shallow water that doesn't move, which if you think about it isn't that surprising. If you pump it out a bit further, you quite literally have a whole ocean to dilute the salt in. Off the coast of California, for example, which is a state that should have no water shortage as it has abundant access to clean solar and wind energy and the entire pacific to desalinate, ocean depths drop quickly even just a few miles out. You would not be able to affect salinity levels of ocean waters there in any measurable way even if you wanted to.
So, the solution is pipes and pumps. Those add cost of course but it's a completely solvable problem otherwise. Exhausting natural sources of ground water and aquifers also has an impact. Desalination done right might give some of those stressed ecosystems a chance to recover.
> It's actually only a challenge in shallow water that doesn't move, which if you think about it isn't that surprising. If you pump it out a bit further, you quite literally have a whole ocean to dilute the salt in.
What do the studies say what the effects of stripping water from the oceans and increasig the concentration of salt and other things are?
All the water we take out of the ocean ends up back there after a while, as part of the water cycle, we just borrow it for a bit.
Yea, but it's different. For example, we have harmed ecosystems by our flood, erosion, etc. control of rivers. They're supposed to move, but we don't let them, and that has detrimental downstream, figuratively and literally, effects. And it's because we view rivers as just a vessel or tract of water rather than as part of a system. Analogously, the ocean is not just a bucket of water.
Coastal ecosystems are particularly sensitive and are already at a tipping point. Are they meant to have bits of it pumped out, filtered, and everything but the water dumped back in?
I have been downvoted here, but is it really a bad thing to attempt to understand things a bit better? Before we solve one problem by creating another problem, something humans are really good at?
I wonder, wouldn't we be able to dump it into some flat spaces, allow the water to evaporate and then harvest the salt that remains?
The brine more often than not contains traces of pretreatment chemicals, heavy metals, and other byproducts. It's frequently treated before being disposed of. Methods include pumping it down to the ocean floor or mixing with a source of less salty (wastewater/hydro) runoff. Removing the trace chemicals to make salt out of the brine would be prohibitively expensive.
Just dump it into an active volcano.
Sorry for the extremely ignorant comment: but can't salt be solidified and stored somewhere as waste? and then maybe sold as food or for industrial uses?
Surely it would be more efficient than salt pans or mining salt as we do today...
My understanding is that this system is meant to be used at a small and distributed scale, not at an industrial scale like city-level desalination plants. In that case, it shouldn't be a big issue.
So could it be behind this dead zone? ''The largest such dead zone in the world is in the Gulf of Oman, a strait bordered by Iran, Pakistan, Oman, and the UAE. It occupies a whopping 165,000 square kilometres of the water body, an area bigger than even the state of Tamil Nadu (130,060 square kilometres). https://nyuad.nyu.edu/en/news/latest-news/science-and-techno...
Brine can be pumped into ponds and evaporated for salt. People holding water rights are usually lobbying and spreading disinformation.
I don't know anything but how about putting it in a hole ? What would be the consequences of that ? (Sure there are plenty but I am too dumb to think of any)
The hole will fill up.
https://en.m.wikipedia.org/wiki/Palacio_de_Sal#
The flush tank of my toilet was leaking. I called a plumber, and the first thing he did was to scoop up more than 2 handful of salt solids from the flush tank and clean it well - I wasn't aware that our community uses untreated hard water for toilets. And I was shocked, as I wasn't aware this happened, at the amount of left over salt that had accumulated!
Salt is a by-product of desalination and, as I understand, not easy to dispose without affecting the ecology of the area where it is disposed (let's not forget that salting of fields was done as an act of warfare against the enemy to make their lands barren, and then there's the natural Dead Sea - https://en.wikipedia.org/wiki/Dead_Sea - that exists and highlights what happens to marine life when water has too much salt content in it). Unless salt waste disposal is solved, desalination isn't going to become popular.
Put it in a box and use it as a heat battery for solar/wind
Wouldn’t the rising sea levels more than counter any salt being returned to the sea, as long as it’s dumped far out enough? Won’t climate change cause the concentration of salt in seawater to go down?
Use it for food consumption.
Even if the water produced by this process is like distilled water(without the minerals needed for drinking water), if it is cheap enough, and scalable enough, countries like India, Arab countries and northern African countries could theoretically pump in such clean water into the ground and mix it with the little fresh water they have in their land… Setup the system to produce a 100 million liters per day, and pumping into ground inland should still replenish the ground water levels enough while earth does its thing to add the needed minerals…
Heck use such water to plant trees where it would not have been possible otherwise…
This. It may seem like wishful thinking, but the problem of desertification is so immense that we ought to approach any potential remedy with first principles and determine feasibility.
Could passive desalination be a way to bootstrap local ecosystems in arid environments to a degree where it would be self-sustaining?
Dupe: https://news.ycombinator.com/item?id=37675831
Confused by the "... that is cheaper than tap water". Growing up on an island with desalination, that was our tap water!
I assume you understand that the vast majority of the tap water is not in that category?
Well I’d hazard a guess that this new desal method isn’t cheaper than well water for rural areas where that’s an option.
Or surface water for areas with plentiful rain.
And I’d further hazard a guess that their cost analysis hasn’t scaled up or thought about distribution.
And their invention is pretty useless for people inland since then it requires the distribution that makes many of the other systems costly.
Basically the title is PR bunk is what I’m saying.
Tap water has to come from somewhere. Dig a well, dam a river or desal the ocean, they all have significant costs to produce, treat, and distribute the water.
Even if you did build one of these devices outside your house, you'd still need to pressurize and plumb it into your house's water supply.
Simply producing water is but one step among many to make that water usable.
Yeah seems like a category error: desalination is a mode of production, tap is a mode of delivery
I think it is time for internets to adopt a second heading/headline. It can explain what the article is about like in the good old days, the first one can bait the clicks. We all want better click bait but also to know wtf is going on. "It produces unlimited FREE drinking water!" => "remove salt residue from solar distillation apparatus"
When you introduce second field, it will ALSO be used for clickbaiting.
Also, if the second field is too much informative, I don't need to read a lot of articles anymore.
Why is a new and cheaper desalination invention in the news every 3-4 years?
Water is important.
And fresh water is increasingly scarce, and desalination is energy intensive.
And since we’re stating the obvious, seawater is particularly abundant.
and seawater is salty, making it unfit for drinking and irrigation
I feel like we see these in that cadence, but do we see them becoming commercially viable or actually in use at scale at all?
I don’t know about elsewhere but I live in Perth and we have a desalination plant that supplies 15% of our drinking water.
https://www.watercorporation.com.au/Our-water/Desalination/P...
I think we've got another one at Alkimos that supplies another 15% or so right? I think we are projected to have the majority of our drinking water come from desal over the next few decades.
Desal is cheap as chips compared to Water Corp's supply charge!
Yeah Alkimos just past the private school.
And it’s a pretty recent thing too since we realised we couldn’t just blindly drain the underground water and the rain had become insufficient for our long term population growth predictions.
The world leader in desalination is Saudi Arabia with it producingover 37% of their water supply
> Water desalination in Saudi Arabia has doubled over the past decade to reach 2.2 billion cubic meters in 2021 [0]
Then United States is right behind at #2. It does seem like a lot is happening it just has to be the perfect storm of correct conditions.
[0] https://www.arabnews.com/node/2160116
Water and food are the absolute essentials to life. If meta came up with a new product, you can ignore it, but you cannot ignore water scarcity.
Most nations are beginning to deal with intense water pressure issues. Especially as seasons don't follow the patterns so perfectly. A flash drought could cripple almost all water and excessive underground water pumping sinks the land. See china's issue with random potholes due since the land is sinking.
Modern water desalination is quite new, so technology has much room to grow. Not only does that make it attractive in terms of patents for better systems, but also there's always a market.
It's important news for dry countries and regions.
Nestle Strawman Inc. Just bought the patent.. Wish there were more ip violating nations out there, allowing tech progress to flourish.
China tends to do well there.
Yeah, but they would do much better if they had a legal system protecting there internal inventors and geniuses from party corruption and harmony idiocy. Nothing new can be introduced harmonious
It seems like the constant stream of innovations coming out of China directly refute "Nothing new can be introduced harmonious"
oh gosh really? there goes my optimism :|
Flushes out the accumulated salt?
Sea salt sells for about $3/lb
I think if you did it at that scale it might flood the market and push the price down. You might be able to trade it to areas with a legitimate need, but you'd be competing against the people who just scoop it from ancient seabeds with a bulldozer.
considering that 6 months ago, 3 lbs of salt was sold for $2.29 (pnw, Oregon) and now sells for that for a single lb, that might be ok to flood the market and lower the price. if it can be disposed of for that price.
shrinkflation sucks, it doesn't mean we need to be beholden to it.
The price is already just about as low as it's reasonably going to go, with the price being dominated by factors unrelated to the actual production of the salt. Your average person consumes under ten grams of salt per day. The market simply isn't that large, and it's easy to make it in bulk at those scales.
so then a 3x price increase is justified by ...
* labor (no, price for labor hasn't increased 3 fold)
* transport (no, the price for transport hasn't increased 3 fold)
... still looking for an explanation why prices would increase 3x, and allow the packaging to be redesigned to be 1/3 of the size but with new plastic (as opposed to cardboard/recycled) and be sold at the same price.
if you can lower the cost of the original product, shouldn't you also be able to avoid some shrinkflation/redesign/platicification?
It might mean a 3x increase in margins for the producer or reseller, as has been the case for a lot of the price increases seen after the pandemic.
Or, most realistically, it's a combination of all of these - some increase in labor and transport prices, some increase in the producer's margins and some in the reseller's. Not to mention various other intermediaries taking their own cuts.
But sea salt hasn't gone up 3X in price. You have to look at actual market rates, not the arbitrary price being charged by one single store that's raising prices because they can (and which they'll do for any product). Searching right now, I'm seeing around $0.60/lb for bulk sea salt, e.g.: https://www.webstaurantstore.com/regal-salt-sea-fine-25/1020... And note that it might be cheaper still from a local supplier if you go pick it up in person.
Or, to put it a different way, the responsibility is on you as a consumer to actually get the best price on whatever you're shopping for. Some retailers can raise the price arbitrarily high, but you don't need to fall for it.
flood...the market!
A lot of energy goes into drying that salt and preparing it for sale.
Just use the sun for energy and sell the salt to recupe the money from transportation.
The entire earth doesn't need the amount that would be produced as waste for one cities drinking water.
Salt deposit clog the devices, harvesting the salt sould require labor. Rejecting the salt allows the device to run passively for years.
[Brief check on Amazon]
Purified, crystalized, brand-name, food-grade salt, delivered to my doorstep, is about $3/pound. Demand for that is pretty limited - how much more salt would you use, if you could buy it for only $1.50/pound?
Vs. this device produces "concentrated seawater" - which still contains every bit of algae, fish poop, plastic pollution, etc. that was in the original seawater.
Looking at this as a 'black box', You have the heat resource of the sun that will heat all the water. Let us say 10% evaporates and condenses into the storage area, the remainder is now 3.5% salt plus .35% saltier and it maintains it's heat. If you allow 10% to exit and be replaced with cold 3.5% salt water, AND it exits via a counter current heat exchanger = heat stored is kept, the added .35% salt is a minor effluent and will disperse. The greatest problem is the propagation of algae and suspended sea life that will soon proliferate to clog all surfaces, with free floaters exiting as well. Any salt/fresh water aquarist will know that this will be a problem. The system will work until the algae problem(not to speak of clam/mussel/barnacle etc larvae that are ubiquitous in sea water.
Does anyone know where I can find the original paper with the design or something?
It's frustrating how often science news articles like this one don't include a DOI or a link to the journal.
Looks like this is the paper https://www.cell.com/joule/fulltext/S2542-4351(23)00360-4
I would look and see if they have tried to patent the system. I'm unable to search anything immediately, but patents and followed by licensing to the associated startups are bare minimum steps that needs to happen to have any confidence that the system can pan out in real life.
Only if desalinated water is banned from being delivered to taps, else the two would be the same price?
It's a weird comparison, but no if desalinated water is being delivered to taps you'd expect deslinated water to be cheaper than tap-water, if you take the price at the source instead of the price after a (not free) delivery process.
I think OP is saying that if desalinated water is being delivered to taps, then it is tap water.
I agree that's what OP is saying, I'm saying that's not true. The "is" operator here isn't commutative, "tap water is desalinated water" is true, but "desalinated water is tap water" is not.
Let's put some numbers to it. Assume tap water is desalinated, it costs $1 to desalinate a unit of water, and $1 to deliver a unit of water to taps. Then tap water is going to cost $2 while desalinated water only costs $1. Delivery to taps isn't free, so if you just want to buy bulk desalinated water it's cheaper.
I assume the implication was "cheaper than the current typical cost of non-desalinated tap water."
It doesn't list the cost of Tap Water. Which I assume would be different in most part of the world.
And then 25% of it are wasted in pipe leakage.
It's not about cost, it's about quality
If everyone uses this suitcase, how is access to the coastline regulated? Does the water come to the house with a pump? Or by bucket?
>could >maybe >not really
Only innovating on price, not on dealing with the toxic brine dumped into the shores (ocean shores are a bio-diverse eco-system in itself, that you can't find in the rest of the ocean).
What if you dump the brine 10 miles into the ocean via pipes? The desalinated water has to make its way back to the ocean somehow, I would not be worried about us making an impact on the Earths ocean salt levels, and if we dump the brine far enough into the oceam, there must be cubic power laws about salt dissipation.
Yes, that would be trivial.
I wonder if this is not done because it's expensive (maybe brine corrosion requires expensive pipes), or because governments will simply do nothing until there is public outcry (unlikely to happen in Saudi Arabia, they would need international pressure).
Or just dump the brine on the ground in a dump site. Let the water seep away underground and the salt pile up to eventually be bulldozed away from the pipe outlet when it gets too high.
I'm picturing something that looks like mine tailings.
Possibly the stuff could be sold as pavement salt for cold climate markets. Depends on how dirty it is I suppose.
Price is the only barrier to desalination. Environmental impact is a problem to be solved, but we never try to solve it for other things, so why for this?
I know the HN community will hate my comment, but Musk has been talking about desalination since at least 2018, claiming it's the solution.
And?
A lot of people have.
And people were actually doing large scale desalinated water at least 20 years before that, because it’s a pretty well known solution - why do you need to bring up Musk?
I have a mate down the pub who claims to have solved world hunger.
He also claimed to have stopped WWIII.
Doesn't make him credible.
Musk has been talking for five years about a topic that's been discussed in depth everywhere for the past twenty years and your conclusion is what exactly?