Desalination system could produce freshwater that is cheaper than tap water
news.mit.edu
news.mit.edu
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."
I wouldn't call it an unsolved problem necessarily. We probably disrupt the ecosystem more when we build a parking lot.
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.
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.
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?
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.
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.
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.
What do the studies say what the effects of stripping water from the oceans and increasig the concentration of salt and other things are?
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?
So what is the problem then? We only need to lay pipes to ocean floors that are already not that lively?
So long story short we probably care about sea life.
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?
I ran into this, it seems to explain how the sausage is made:
https://iopscience.iop.org/article/10.1088/1742-6596/1968/1/...
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?
> 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.
Adding your 12 cities would double the supply.
"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.
In that volume, you need a large drying pool.. which is no better than a parking lot.
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-...
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.
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.
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.
https://www.bbc.com/future/article/20150610-blue-energy-how-...
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.
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.
How've you determined this?
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.
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.
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.
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.
Much of the price of that is coming from not breaking the formed patterns during harvest.
edit: Or here Aljazeera https://www.youtube.com/watch?v=PgDiW2ELx7k
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.
Surely it would be more efficient than salt pans or mining salt as we do today...
Let's try that before jumping to popular political positions of ridicule and dismissal.
And seawater has ~3.5% salt content by weight, not 1.5%
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.
https://en.wikipedia.org/wiki/List_of_bodies_of_water_by_sal...
Haven't heard of that before. Wouldn't it mean there are underwater areas carpeted in salt crystals?
Heck use such water to plant trees where it would not have been possible otherwise…
Could passive desalination be a way to bootstrap local ecosystems in arid environments to a degree where it would be self-sustaining?
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.
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.
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.
https://www.watercorporation.com.au/Our-water/Desalination/P...
Desal is cheap as chips compared to Water Corp's supply charge!
> 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.
Sea salt sells for about $3/lb
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.
shrinkflation sucks, it doesn't mean we need to be beholden to it.
* 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?
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.
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.
Looks like this is the paper https://www.cell.com/joule/fulltext/S2542-4351(23)00360-4
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.
And then 25% of it are wasted in pipe leakage.
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.
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).
He also claimed to have stopped WWIII.
Doesn't make him credible.