Solar-Powered Desalination Device Wins MIT $100K Competition (mit.edu) 77
The winner of this year's MIT $100K Entrepreneurship Competition is commercializing a new water desalination technology. MIT News reports: Nona Desalination says it has developed a device capable of producing enough drinking water for 10 people at half the cost and with 1/10th the power of other water desalination devices. The device is roughly the size and weight of a case of bottled water and is powered by a small solar panel. The traditional approach for water desalination relies on a power-intensive process called reverse osmosis. In contrast, Nona uses a technology developed in MIT's Research Laboratory of Electronics that removes salt and bacteria from seawater using an electrical current.
"Because we can do all this at super low pressure, we don't need the high-pressure pump [used in reverse osmosis], so we don't need a lot of electricity," says Crawford, who co-founded the company with MIT Research Scientist Junghyo Yoon. "Our device runs on less power than a cell phone charger." The company has already developed a small prototype that produces clean drinking water. With its winnings, Nona will build more prototypes to give to early customers. The company plans to sell its first units to sailors before moving into the emergency preparedness space in the U.S., which it estimates to be a $5 billion industry. From there, it hopes to scale globally to help with disaster relief. The technology could also possibly be used for hydrogen production, oil and gas separation, and more.
"Because we can do all this at super low pressure, we don't need the high-pressure pump [used in reverse osmosis], so we don't need a lot of electricity," says Crawford, who co-founded the company with MIT Research Scientist Junghyo Yoon. "Our device runs on less power than a cell phone charger." The company has already developed a small prototype that produces clean drinking water. With its winnings, Nona will build more prototypes to give to early customers. The company plans to sell its first units to sailors before moving into the emergency preparedness space in the U.S., which it estimates to be a $5 billion industry. From there, it hopes to scale globally to help with disaster relief. The technology could also possibly be used for hydrogen production, oil and gas separation, and more.
video (Score:2)
The video is great.
https://www.vice.com/en/articl... [vice.com]
Article link (Score:5, Informative)
Here [mit.edu] is a more informative article.
Instead, their unit relies on a technique called ion concentration polarization (ICP), which was pioneered by Han’s group more than 10 years ago. Rather than filtering water, the ICP process applies an electrical field to membranes placed above and below a channel of water. The membranes repel positively or negatively charged particles - including salt molecules, bacteria, and viruses - as they flow past. The charged particles are funneled into a second stream of water that is eventually discharged.
There's then something called electrodialysis to remove any remaining salt ions.
Re:Article link (Score:5, Funny)
The only downside to the ICP process is that the water comes out tasting a bit like Faygo.
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Addition of magnetic filters to the process should fix that.
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How the fuck does that work?
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I'm not saying it's a miracle... but it's a miracle it does work.
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Fucking magnets...
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You're not supposed to put magnets in your RealDoll.
Re: Article link (Score:5, Funny)
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No, I didn't know that and I'm sorry to know it now. ;-)
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foul tasking water is MUCH better than NO water
I could also see this being combined with something like a LifeStraw to do final quality filtering, while dramatically increasing the lifespan of the lifestraw.
I suppose good-tasing water might become a 'treat" in some parts, where lifestraws are a limited supply?
Re:Article link (Score:5, Informative)
The MIT article provides some actual metrics about how much energy is consumed by this process. It states that:
Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watt-hours per liter.
When I read TFA and encountered the claim "with 1/10th the power of other water desalination devices" and "Because we can do all this at super low pressure, we don’t need the high-pressure pump [used in reverse osmosis], so we don’t need a lot of electricity" my hype-hackles went up because reverse osmosis is approaching the thermodynamic limit of efficiency. No process can be invented that uses "1/10 the power" of reverse osmosis at scale.
The power consumption of reverse osmosis at scale is as low as 2.5 KWH per cubic meter which is 2.5 watt-hours per liter. In other words this unit is eight times more energy consuming than reverse osmosis, not ten times more efficient.
The advantage of this device is that it does not need the expensive and heavy high pressure pump and so can be made smaller and lighter and cheaper and have a lower power (but much less efficient) operating mode. It is okay to have an inefficient but small cheap solar powered personal water producer, not everything has to be efficient especially if free energy is used. But you should be honest about the advantages the technology has, not imply advantages that it does not.
Another thing about the technology is that makes water that is less pure than reverse osmosis -- again, this okay but it should be stated. The device works until it gets the purity down to acceptable consumption standards, but it does not produce nearly pure water like reverse osmosis.
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They are comparing it to other small scale desalination methods, which it is considerably more efficient than.
For large scale desalination, as you say a large, heavy and expensive system is more efficient.
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my hype-hackles went up because reverse osmosis is approaching the thermodynamic limit of efficiency.
Reverse osmosis has nothing to do with thermodynamics.
Perhaps you wanted to say "is at its theoretical maximum efficiency" or something like that.
What irked me in the summary is: The traditional approach for water desalination relies on a power-intensive process called reverse osmosis.
Which is simply plain wrong. Reverse osmosis is not power intensive, it is actually pretty cheap. Does not mean that this
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Reverse osmosis has everything to do with thermodynamics. You are decreasing entropy by separating the salt from the water, and that requires energy.
But I think the key to this invention is in the headline. It can use solar electricity. Whereas presumably reverse osmosis requires a different type of electricity? :(
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Reverse osmosis has everything to do with thermodynamics. You are decreasing entropy by separating the salt from the water, and that requires energy.
And that involves which law of thermodynamics?
Oh ... none. So, problems like this can not be calculated by "calling on laws of thermodynamics".
Re: Article link (Score:2)
Cheap and power efficient? (Score:2)
Reverse osmosis is not power intensive, it is actually pretty cheap. Does not mean that this way is even cheaper.
Literally every single time I've heard of a major desalinization plant being proposed the very first thing that comes up is the huge amount of electricity it will consume and how expensive they are to operate. Every single time and I've never heard the claim in response until just now that these systems are not actually power intensive and by extension "cheap". And by "heard" I don't mean just on the evening news, I also mean the official government reports on the subject.
Obviously you're making a claim tha
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Operating a huge plant (regardless what it does) obviously consumes an appropriated huge amount of electricity.
However you have to put that into context.
E.g.
a) a Aluminium plant producing Aluminium from Bauxite (the raw mineral) - versus -
b) an Aluminium plant producing fresh Aluminium by recycling old ones
The energy difference is gigantic.
Regarding reverse osmosis and water, it costs more to transport a ton of water to the local super market than it costs to desalinate it.
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The only comparison I think that would be meaningful in this context would be comparing the cost desalinated water versus the cost of other means of obtaining water.
In that vein, https://theworld.org/stories/2... [theworld.org]
"A thousand gallons of freshwater from a desalination plant costs the average US consumer $2.50 to $5, Pankratz says, compared to $2 for conventional freshwater"
That's a 25% to 100% price difference. At scale that that seems like it would be quite a bit more expensive to me.
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Hahaha, sorry I'm pretty tired right now. 100% = 125%
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The amount of water a standard person uses is not enough that 2x or 10x the price makes any difference.
So (pro)claiming that some way of desalination is "super power hungry" does not make any sense. And we talked about "energy intensive". Reverse Osmosis is not really energy intensive. Even mediocre Spanish hotels at the coast have Reverse Osmosis fresh water plants as it is cheaper than getting the water trucked in.
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Even mediocre Spanish hotels at the coast have Reverse Osmosis fresh water plants as it is cheaper than getting the water trucked in.
Of course its cheaper than trucking the water in. Trucking water in is hardly the standard means of delivery water to anywhere in first world countries though. All you're doing here is cherry picking a piece of outlier data and claiming because desalinization is cheaper then that (literally the least efficient means of water delivery), that means it's no expensive.
A proper comparison would be comparing desalinization to the traditional forms of first world water delivery to homes, business', and farms. I've
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that means it's no expensive.
Because it is not expensive.
Seriously? Look up how cheap it is ...
Why do I need to cite something you can google? Sorry, learn how to use a computer.
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Reverse osmosis is not power intensive
What is and is not "power intensive" is relative to the task and amount of power you have available. Internet claims that reverse osmosis uses 3 to 10 kWh / m^2 That may be good when comparing it to other desalination methods, but it's a lot worse than the system described in the article.
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m^2, or m^3?
m^2 is not actually a meaningful measure of the amount of water processed, so I'm assuming m^3. And 1 m^3 = 1000L, so your numbers translate to 3 to 10 Wh/L. Considerably less than the 15.6 to 26.6 Wh/L they're claiming for this process in their paper (https://pubs.acs.org/doi/abs/10.1021/acs.est.1c08466 )
Granted, that's for seawater - they're claiming only 0.4-4Wh/L for merely brackish water. I'm not sure how reverse osmosis compares for that, so there could be a sizable niche where this tech
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I simply have a problem with people claiming "X is power intensive" when X is actually pretty common/economic/low power solution.
E.g. hydrolysis: 70% effective, minimum calling that power intensive is just stupid.
Desalination, what can you do? Hu? You can evapour (no idea why that word is red underlined, how do you spell it?) water, and have the slat left. THAT is energy intensive. Or you can use reverse osmosis. Which nearly costs no energy at all. It is just not feasible in small plants, so you have to bu
Re: Article link (Score:2)
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That is a great logical analysis, thanks. You are a breath of fresh air here!
I miss the old slashdot
Evaporation? (Score:4, Interesting)
Re: Evaporation? (Score:5, Interesting)
Most is good enough for you? You want to take that risk, knowing pathogenic bacteria such as those of the species actinomycetes and maybe even campylobacter can survive at that temperature?
Water has high specific heat capacity - lots of en (Score:4, Informative)
> Heat to promote evaporation
Water has a high specific heat capacity. In other words, it takes a lot of power to heat it up just a bit.
Perhaps more to the point here, it also has a high latent heat of vaporization. That is, the amount of energy you have to input to evaporate it. That's actually much higher than you'd expect from multiplying the (already high) specific heat capacity (because vaporization causes cooling, undoing the work you did heating it - note how a mist of water cools you off on a hot day). The latent heat is 40.65 kJ/mol, This is due to the strong bonds between hydrogen.
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You distill water at low pressure. So it boils at room temperature. So better than just boiling it in a kettle.
Re: Evaporation? (Score:4, Insightful)
If distilling the water was the cheapest way to desalinate, we wouldn't be using reverse osmosis.
Re: Evaporation? (Score:3)
Re: Evaporation? (Score:2)
Definitely of you're using waste heat it works real efficiently.
I think for large scale desalination they do vacuum distilling sometimes, as it's more energy efficient than using heat.
Re: Evaporation? (Score:5, Informative)
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Wouldn't distillation manage to remove any organisms?
Re: Evaporation? (Score:5, Informative)
Re: Evaporation? (Score:2)
Neat.
Thanks for explaining.
Re: Evaporation? (Score:5, Informative)
In these designs, the brine effluent that is returned to sea has had roughly 50% of the water removed. In a scenario like yours with a fixed basin for evaporate, you are not accounting for the large scale formation and chloride pitting from much higher concentration of chloride. This will, at the very least, require a lot of NiCu and CuNi alloys that are resistant to chloride corrosion. The sodium scaling will continue to be a maintenance nightmare.
parasites (Score:2)
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I would think going from 5% NaCl to ~0% would kill nearly all microbial life present. OTOH, I would think a thermal vent in perpetual darkness at the bottom of the ocean would be a lifeless environment.
In any event, the water's potable. If you're worried about microbes, drop in an iodine tablet, chlorinate it, UV irradiate it . . . whatever makes your boat float. If you get thirsty enough and this is what you've got, you'll drink it.
Re: parasites (Score:2)
good for use-case, but does not scale (Score:5, Informative)
I was curious why there was no mention of this technology being used on large-scale desalinization, found this link from 2010
"While the amount of electricity required by this method is actually slightly more than for present large-scale methods such as reverse osmosis, there is no other method that can produce small-scale desalination with anywhere near this level of efficiency, the researchers say. " https://news.mit.edu/2010/desa... [mit.edu]
Civilization needs something better than reverse osmosis / solar stills, so I appreciate their new way of thinking. It would be nice if some aspect of this tech could be scaled up.
Maybe it could scale... (Score:2)
Thanks for looking that up, I was wondering the same thing....
But if electricity used at scale is the only factor, maybe this would be the perfect technology to pair with small modular reactors to provide desalination stations along the coast - the fact pressure is not involved makes it seem like it would be cheaper to build out, and less maintenance would be involved. Also without high pressure perhaps intakes could be simpler so as to not harm sea life (the sticking point for current declination efforts
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Possible idea, except that the reactors would have to be located in Arizona.
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It sounds funny, but having some land you don't care about right next to a bunch of big desalination plants would be a great idea. That's how we get lithium deposits, after all.
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Too salty to just put it back in the ocean;
I have some news for you about what ocean water has in it...
Seriously though, brine dumped back into the ocean would disperse rapidly.
Or you just pile it up somewhere in the Mojave.
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Except that, as we can see from many desalination plants around the world, it doesn't. You tend to get large dead zones around the outlets where the salinity is too high for most ocean life to survive.
That's fine if you don't care about sterilizing a chunk of the ocean's most limited and fertile coastal regions - but rather more concerning if you're environmentally conscious.
And spreading out the outflow to mitigate the damage requires lots of expensive undersea plumbing that requires constant maintenance
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I think the kind of scale where this makes sense is producing enough water to keep a few people alive; as soon as you've built a nuclear reactor, an RO unit to go with it is small change.
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If you've got an SMR, you're already talking a scale (multiple MW) where reverse osmosis probably makes more sense.
This seems better suited to small applications like villages or individual households, where a few solar panels can provide more than enough power.
I don't think the pressures required for RO would have any impact on intakes - by their nature intakes can only operate at ambient water pressures - the high pressures exist within the processing plant, where most life already has to have been remove
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This is a more accurate (or honest) statement than TFS which seems to claim "ten times more efficiency" than reverse osmosis, but if the TFS claim of 20 watt-hour per liter is generally true for this technology, then it is way more than "slightly more" - it is eight times more energy consuming.
But small commercial reverse osmosis units with their own driving pumps (not water main pressure driven) start at a few hundred gallons a day, and the pump pressure required is 200 PSI, which is not all that high real
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RO in fact is approaching the thermodynamic limits of efficiency for separating salt from water in the best plants.
RO, aka Reverse Osmosis, has nothing to do with thermodynamics. Hence there is no thermodynamic limit. No idea why people come up with this nonsense.
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So, you have no idea why thermodynamics [mit.edu] has anything to do with diffusion or pressure? [sciencedirect.com]
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Exactly, you need to find niche cases.
In general thermodynamics has absolutely nothing to do with reverse osmosis, and pressure of liquids.
But thanks for playing.
If you like to comment on your two links, I'm open to listen.
I guess you did not read either of them, lol. Otherwise you had realized: it is the same paper published on two different web sites - you are such an idiot, unbelievable.
Re: good for use-case, but does not scale (Score:2)
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From the fine linked article:
Yes, I know - you're upset that somebody listened to the environmentalists, who showed up with scientific research instead of just ledgers.
Also from the fine linked article:
Re:Not in Nimby California (Score:5, Insightful)
Not all commercial projects are a good idea. California already has the largest desalination plant in the Western Hemisphere (the Carlsbad plant) and all the urban areas in California use only 20% of the water available for use (agriculture uses 80%). The proposed Poseidon plant has the problem of being a bad economic solution. It would be paid for by mandatory water rate increases, and more efficient use of that money would come from water conservation measures.
Furlongs per fortnight (Score:1)
capable of producing enough drinking water for 10 people at half the cost and with 1/10th the power
How much water do 10 people drink? What's the cost? How much power? Without real numbers it's gibberish
It was only a matter of time (Score:3)
I always figured desalination would become cheaper/more efficient the closer it came to being necessary.
You can't have water shortages on a planet that is more than 70% water.
It's just that no one cared enough to put resources toward solving the issue to make it more efficient until recently.
Efficient and inexpensive desalination will be a game changer for places like Australia.
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Actually, you can have water shortages Plenty of water, most of it perfectly suited to most of the life on the planet.
Sucks to be in the minority. "Efficient and inexpensive" remain to be seen. I haven't seen any new technologies lately which started out inexpensive. Remember when rounded corners on a cell phone first came out? How many people paid a fortune to have a phone with those rounded corners?
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Can't have water shortages when it's the most abundant resource on the planet. The only issue is finding a way to purify it, and as this article shows we are well on the way to finding a way for that to be efficient.
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And what have rounded corners to do with anything?
Is that a stupid american myth?
You by a phone because you need a phone.
Then you look for features.
Then you look for budget.
What the fuck have corners, rounded or not, to do with anything about a phone?
And as: every damn phone has rounded corners - your comment makes no sense at all.
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And as: every damn phone has rounded corners - your comment makes no sense at all.
How easily people forget their own history, let alone sacrifices of others so they could casually enjoy the privileges they're not even aware of any more. [penny-arcade.com]
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"You by a phone because you need a phone.
Then you look for features.
Then you look for budget."
So you buy a phone and then look for features and your budget? Is that upside down Australian logic there?
Maybe get your posts straight before you start throwing stones at other people's countries. The above poster was a twit, that doesn't mean you have to be one
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That is my line of priorities, no idea what yours are :P
And round corners on a phone are a must, or do you want to poke your fingers all the time when you grab into your trousers pockets? No idea why anyone would object against rounded corners or even make that an issue. Never had a phone where the corners where nor rounded.
What to do with millions of tons of salt ? (Score:1)
What ever happened to Dean Kamen's Slingshot? (Score:2)
About 10 years ago, Dean Kamen (inventor of the Segway), was working on a project to create a highly efficient water purifying system [wikipedia.org]. The Wikipedia article on it is really out of date. Does anyone know what happened to it?
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Doesn't sound any better, efficiency wise, than existing large-scale options. 1kW for 1000L/day is still 24Wh/L - at the high end for this process (15.6-26.6Wh/L), and much higher than the 3Wh/L typical of reverse osmosis desalination https://en.wikipedia.org/wiki/... [wikipedia.org]
The fact that it supposedly produces water pure enough to be suitable for medical injection is interesting though, as is the fact that it apparently does so at small scales.
The fact that the prototype apparently cost $100,000 to build is less
Solar Still + ceramic filter. (Score:1)