12 ms·

From seawater to drinking water, with the push of a button

258 points by happy-go-lucky 4y ago

zubairq 4y ago
Amazing! Is this a game changer?
- siruva07 4y ago
  Maybe. I think Atmospheric Water Generators are much More likely to change the game since they don’t need a body of water other than the atmosphere.
  - deleted 4y ago
    [deleted]
  - stephen_g 4y ago
    There are big thermodynamic problems with those, the phase transition requires a lot of energy... Generally the main places where they work with any kind of acceptable efficiently and decent yield (where there's high enough humidity) are also the places where it tends to rain a lot!
  - MichaelApproved 4y ago
    “Atmospheric Water Generators” At first I thought you were just using a marketing term for dehumidifiers but I looked it up before posting. I see that term is used for tight mesh fabric that’s hung vertically as a passive matrix to collect condensation. While those are actually game changers, they unfortunately only work in special regions that have the needed weather and topography to make them work. I think there’s only one place on earth that has the perfect combination for AWG: weather, drought, and humidity. It’s an awesome technology for them but that’s about the extent of it. I’ll try to find the region and update my comment with more info. Edit: here’s a video that talks about what I think you’re talking about. https://youtu.be/YxRONAZoMDk https://youtu.be/YxRONAZoMDk It’s providing water in the Atacama Desert near Lima Peru. Edit 2: They’re called fog collectors and apparently Morocco uses them too. https://youtu.be/0F7CQMd6mQ4 https://youtu.be/0F7CQMd6mQ4
    - fiddlerwoaroof 4y ago
      I wonder if you could use a similar sort of device with weather balloons to harvest water from clouds.
      - kortex 4y ago
        I could totally see a Project Loon style craft which automatically surfs the crosswinds, going up above the clouds to radiate heat to the open sky at night, and descending to condense water.
      - MichaelApproved 4y ago
        Would dry regions that need water have enough cloud coverage for that to be viable? My guess is that any place with sufficient cloud coverage is already getting enough rain water to satisfy their needs.
        fiddlerwoaroof 4y ago
        I think there are parts of coastal California where there are clouds more of the year than rainfall. I'd also suspect if you just raised them up with balloons to cool them off and then brought them down where it's warmer, you could condense evaporation from the ocean, without spending energy directly on cooling.
        MichaelApproved 4y ago
        You’d have to raise them up pretty high to get them colder than the dew point. The energy it’d take to raise and lower the material would make it cost prohibitive. I considered that the balloons would be a balancing force but don’t forget the rope length changes as the balloons go up and down. That changing length shifts the weight around. You can’t be balance against it.
    - FR10 4y ago
      > It’s providing water in the Atacama Desert near Lima Peru. I think one big issue is that in winter (May-September) not every day is foggy, so sure its helpful but not a perfect solution. It does get really foggy though in June-October. Thus we get natural vegetation in otherwise arid hills around Lima, the most popular called Lomas de Lachay[0]. [0] https://en.wikipedia.org/wiki/Lachay_National_Reserve https://en.wikipedia.org/wiki/Lachay_National_Reserve
- qayxc 4y ago
  Probably not. It's more expensive than available alternatives (according to the article they use expensive materials) and the performance is poor compared to commercially available alternatives. Might be useful for certain niche applications, but outside of that it's more of a proof of concept at this point.
nullc 4y ago
So how is this distinguished from existing commercially available continuous electrodeionization?
- qayxc 4y ago
  Uses less power and is portable? That's pretty much all I could gather from the article.
  - nullc 4y ago
    That's its claimed advantages against reverse osmosis.
MichaelApproved 4y ago
Edit: I wrote out the comment below criticizing the efficiency of this device, when compared to reverse osmosis RO desalination (100x less efficient). However, they’re not trying to be more efficient than RO devices, they’re trying to be more compact, portable, and avoid the need for filters. They’re solving for a different problem than I was measuring them against. In my race to criticize, I overlooked those key details. I still think my comment is worth reading to learn about the efficiency differences but I guess that measurement is not important for the viability of this technology. Original criticism below: ——————— I’m skeptical about how practical this actually is. While it’s refreshing to see a drinking water solution that isn’t based on inefficient dehumidifier technology, this still seems impractical. From the demonstration video, their portable ~50 watt solar panel took 30 minutes to get a few ounces of drinking water. It looked like a cold winter day, so let’s be generous and assume the panel only produced 15 watts of power during those 30 minutes. Let’s also be generous and say they got 5 ounces of water. That means they produce 1 ounce of water for every 3 watts. That’d be 333 ounces per kWh. To put that into perspective, a desalination plant produces more than 100x that much. Yes, there is lots of additional infrastructure to consider with a traditional desalination plant but It’s not like this solution wouldn’t require the same complexity to scale up. I don’t remember the cost of dehumidifier drinking water “solutions” but I think this is slightly more efficient than those horrifically inefficient solutions.
- tomxor 4y ago
  From the article it sounds like they are looking for ways to scale down (i.e small portable units are the target form factor, not a mere demo), and this is where it compares favourably against things like reverse osmosis for efficiency.
  - MichaelApproved 4y ago
    I was so quick to criticize technology that I completely overlooked those points. Reading the article again, it’s embarrassing to see that I missed it when they were emphasizing it so much. I have one more lingering criticism that I don’t think they addressed (I reread it twice). What happens to the salt after it’s removed? If they don’t have a filter, where does it go? Do they pump brine water back?
nkingsy 4y ago
From the article: The limitations appear to be expensive materials and scale. 20w per liter .3 liters per hour
- MichaelApproved 4y ago
  The article claims 3x more efficiency in a confusing sentence: ”Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watts of power per liter.” So the unit only produces 0.3 liters an hour but if you wait 3 hours and provide 20 watts of power (7watts/hour), you’ll have a full liter.
  - qayxc 4y ago
    > So the unit only produces 0.3 liters an hour but if you wait 3 hours and provide 20 watts of power (7watts/hour), you’ll have a full liter. That doesn't make any sense. 20W of power draw over 3⅓ hours is ≈67Wh (Watthours, not Watts per hour), so 67Wh per litre (energy use; independent of time) and it takes 3⅓ hours to get this litre of potable water with 20W of power. In other words to get 1 litre in an hour, the device might require ≈67W of power (assuming that kind of perfect scaling is even possible with their design).
    - BeefWellington 4y ago
      The wording in the article is specifically: > requires only 20 watts of power per liter. Whether the article is accurate or not I think you missed that.
      - qayxc 4y ago
        The point is that 7W/hour is nonsensical. It's a non-unit and physically doesn't make sense in any context. The power is independent from the volume. Total energy use is volume dependent. 20 Watts per litre is mix of units that's nonsensical. Watt is Joules (Energy) per second (time), i.e. power. Either time is irrelevant, that is the device draws 20 Watts of power, in which case you can ditch the litre. Or the power draw is dependent on the performance in that more power equals higher throughput. Neither case is in any way shape or form correctly described by "20 Watts per litre". Hope that makes it clearer now.
photochemsyn 4y ago
If this unit is shown to be durable, I imagine it's the kind of thing a lifeboat would have as part of its equipment. Low power means low volume of drinkable water (as energy is needed to separate ions from seawater, by the laws of entropy), so that's really unavoidable with this system. Compare to things like concentrated solar for complete removal of solids from wastewater and seawater, here's an interesting example (relies on condensation of steam): https://influencing.com/pr/99083/novel-solar-powered-water-treatment-tech-awarded-100-000-in-australian-innovation-grants https://influencing.com/pr/99083/novel-solar-powered-water-t...
- Stevvo 4y ago
  This thing is going to cost more and be far less capable than a traditional suitcase or even hand-pump desalinator and you never see those on lifeboats.
dehrmann 4y ago
> The suitcase-sized device...can also be driven by a small, portable solar panel, > Yoon and Kang used machine learning to find the ideal combination of ICP and electrodialysis modules. These bits feel like they were added because ML and solar power will get more clicks.
- eps 4y ago
  > The research was funded ... the Experimental AI Postdoc Fellowship Program of Northeastern University, and the Roux AI Institute That's the cause of the AI part. The solar panel bit probably came from the Army requirements, who's another sponsor.
- SturgeonsLaw 4y ago
  True, especially using ML to determine the size/layout of the components. That could be very easy assessed by varying the sizes in a consistent, linear way, and measuring the effectiveness in subsequent tests, rather than throwing it into the black box of ML.
- SamBam 4y ago
  ML maybe, but solar power definitely not. They show an example use-case as a single-family house in a site of flooding and devestation. An emergency desalinator would definitely need to run off of a small generator or solar.
gonzo41 4y ago
This is a pretty cool development, even if they made this thing the size of a 20ft shipping container it'd be a pretty good development.
kylehotchkiss 4y ago
Southern California is beginning to see more water restrictions - each and every desalination tech advancement is a very hopeful development for the region, and many others in the world that can't get enough freshwater. I hope they can generally work this up to factory scale and put it behind a solar farm and see if that can supply a lot of homes.
- KennyBlanken 4y ago
  The problem is that southern California is trying to grow a shit-ton of crops that aren't suitable for the environment there. The almond industry is particularly guilty in this regard. Desalination will never scale to a level suitable to supply that industry. If anything they'll take that water and just grow even more crops, while still sucking the aquifer dry. Thing is, aquifers compact when you draw water from them too much. That compaction can never be undone. They are slowly rendering that land permanently uninhabitable.
  - qayxc 4y ago
    > Desalination will never scale to a level suitable to supply that industry. Are you sure about that? It's simply a question of economics. As long fresh water from other sources is significantly cheaper, no one's going to invest in large scale desalination. Once this changes it becomes a question of which is more expensive - shutting down the agribusiness or running large scale desalination (which has options, from nuclear to solar to the use of metamaterials).
    - sp332 4y ago
      It is true in California, because you need to dump the concentrated brine somewhere, and doing that at industrial scale will run up against environmental protections.
      - jillesvangurp 4y ago
        There's a big bucket right next to California called the Pacific. Perfect place for sourcing water to desalinate and dumping brine back into without doing anything measurably harmful to salt concentrations in the Pacific. It's like a literal drop in the ocean. Most big Californian metropolitan areas are right next to it. There is no water shortage; just a reluctance to pay a fair price for it. The challenges in California are not technological but political and policy related. Local consumers of water seem to assume that water is like manna from heaven that has to be perpetually subsidized by the government. They feel entitled to it but are not really willing to pay for it; or even invest in common sense ways to reduce their consumption of it because it doesn't really cost them anything.
KennyBlanken 4y ago
If I had a dollar for every project MIT's press office has said will be revolutionary and end (insert major world health/water/resource/energy/food problem), I'd be a very, very rich person. I'm not sure why MIT's press office gets so much favor here, particularly given their/MIT's track record. Post articles by science journals and news outlets that will tell us if this is actually going to work or if it's just yet another go-nowhere project.
- swader999 4y ago
  At least this instance has a workable demonstration. Looking at you battery tech...
yyyk 4y ago
I recall similar in function devices already existed for military use - except they made water from air, which is even more available than seawater: https://www.honeywell.com/us/en/press/2021/05/honeywell-led-team-creating-a-portable-device-that-extracts-drinking-water-from-air https://www.honeywell.com/us/en/press/2021/05/honeywell-led-... https://edition.cnn.com/2014/04/24/tech/innovation/machine-makes-drinking-water-from-air/index.html https://edition.cnn.com/2014/04/24/tech/innovation/machine-m...
- aemreunal 4y ago
  Fun fact, there's vodka made from San Francisco fog: https://time.com/4317269/fog-vodka-san-francisco-hangar-one/ https://time.com/4317269/fog-vodka-san-francisco-hangar-one/
mothsonasloth 4y ago
What about filtering particles which don't have a charge like plastics or biological matter? I guess you can always just boil the water after it's been processed by the portable machine.
- eps 4y ago
  I didn't quite get this part either - > The membranes repel positively or negatively charged particles — including salt molecules, bacteria, and viruses ... Are bacteria and viruses indeed electrically charged? This sounds strange.
  - beanjuice 4y ago
    Yes [0], "Bacterial cell surfaces possess net negative electrostatic charge by virtue of ionized phosphoryl and carboxylate substituents on outer cell envelope macromolecules which are exposed to the extracellular environment." [0] https://doi.org/10.1016/S0167-7012(00)00224-4 https://doi.org/10.1016/S0167-7012(00)00224-4
timonoko 4y ago
Those specifications are much worse than 30 year old PUR-06. It makes one liter per hour with 20 Watts and fits in your pocket. I tried solar panel and windshield wiper motor. But direct-drive windmill was much better as wind blows 24/7 on Baja. https://youtu.be/9xYXWISWv5I?t=390 https://youtu.be/9xYXWISWv5I?t=390 Durability was the issue. I destroyed three units and average was 200 days / 1000 liters, because all-plastic construction. Found no limits on filter durability.
- timonoko 4y ago
  I was planning to make those crucial breaking parts from Carbon Fiber myself, but I was such a poster-boy for PUR that they sended me free PUR-35 ($5000). It makes 3 liters per hour and if you replace the solid-iron pumping shaft it weighs about a kilo. Except one crucial high-pressure valve cannot be made of plastic. I made better one from fiber glass. Thereafter it been running ok for 20 years.
Simon_O_Rourke 4y ago
If this works the way it looks like it does, these devices will be a literal life saver. Would love to see a buy-one-donate-one purchase plan.
yellow_lead 4y ago
Anyone else notice in the beach video that the researcher filled the cup using tubing that was previously on the ground, then drank it? Looks cool though :)
- netsharc 4y ago
  He did wipe the sand off the output tubing... good enough? I guess if I dropped a drinking straw on the ground in an e.g. parking lot, I'd throw it away, but if I dropped it on sand in the beach, I would think "just wipe the sand off and it's clean!"
  - xtracto 4y ago
    Back in the day when I went camping with my parents we used to "wash the dishes" using seawater and sand from the beach. Nowadays people are unnecessarily germophobic.
denton-scratch 4y ago
> requires only 20 watts of power per liter. So if you want a liter, you have to supply 20 watts. For how long? Forever? Does the water instantly become turbid when power is removed? Tsk, tsk, MIT. I would have thought an MIT journo would know what a watt is.
- soVeryTired 4y ago
  > Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watts of power per liter. Not great phrasing I agree but the information is there.
  - qayxc 4y ago
    Nah, still doesn't make any sense either way. Watts is a measure of power, not energy. The amount of power (given they use a pump and electrodialysis) shouldn't depend on the volume. Energy OTOH does. So either their device requires 20W of power - which sounds reasonable as the image shows a <100Wp solar panel next to it - and the volume figure is meaningless. Or the author left out crucial context (e.g. is the power draw correlated with the speed, i.e. 20W @ 0.3l/h). The amount of energy would be 67Wh/l regardless given those numbers. It's just a confused mix of performance (processed volume per hour) and power requirements (which is independent of volume and should only depend on the performance).
  - denton-scratch 4y ago
    The trailing "per liter" seems the problem: I think maybe what they mean is that 20W gets you 0.3 liters per hour? So their machine produces 0.3 liters per hour, and draws 20W? I wish journos wouldn't bandy around terminology and statistics they don't understand. It's getting worse.
    - SamBam 4y ago
      It isn't, though, because that would be 60Wh per liter, but the video actually specifies it's 20Wh per liter. They just stupidly used watt instead of Wh in the article text.
JoeAltmaier 4y ago
With advances, perhaps one day it will be the size of a pack of cigarettes. And thus portable enough to include in an emergency kit!
smiley1437 4y ago
Am I reading this wrong? It uses less energy at higher production rates? This is a verbatim copy of the text at 1:32 in their video: Seawater >> Drinking Water ~ 20Wh/L for 0.3L/h of production rate ~ 15Wh/L for 1.0L/h of production rate so it uses LESS energy to get MORE drinkable water per hour? That seems odd.
- davelondon 4y ago
  I assume this means with a larger device...
  - smiley1437 4y ago
    Okay that makes sense
- SamBam 4y ago
  They show that the 1L/h version uses more elements. I assume there are some efficiencies as you get larger.
davelondon 4y ago
Not sure this is better than reverse osmosis... They mention ~15Wh/L @ 1L/hr... The Katadyn Powersurvivor 40 (pretty compact and 11kg) uses 8.5Wh/L @ 6L/hr... https://www.spectrawatermakers.com/us/us/89650-8013438-Katadyn-Powersurvivor-40-e-12-V-a https://www.spectrawatermakers.com/us/us/89650-8013438-Katad...
- sp332 4y ago
  Once an RO filter gets clogged, it stops working.
sandworm101 4y ago
>> The researchers also created a smartphone app that can control the unit wirelessly and report real-time data on power consumption and water salinity. No no no no. I was all onboard with this seemingly wonderful product until I hit that line. The things that provide fresh water, that actually enable life functions, should NEVER involve controller aps. Switches. Dials. Positive on/off switches. Maybe the occasional touchscreen. But please do not put the need for a working/charged/connected cellphone between the user and their source of fresh water. And they say that this thing uses about as much power as a cellphone charger. Wrong. It requires the power of a cellphone charger to filter water, plus a second charger to power the cellphone running the app.
- joshuaheard 4y ago
  A cell phone app would be handy for remote monitoring and control. Say you lived a mile away from the ocean where it is deployed. You could turn it on and off depending on the tide and know when the container you are filling is full. Having just completed a home remodel where all the home automation features have an app, having apps is a handy way to monitor and control your hardware without leaving your couch, or even if you are off-premises.
  - sandworm101 4y ago
    But does the pipe bringing fresh water into your house use an ap? There are things in this life that are expected to "just work", that are so basic they should not be trusted to aps. This product isn't for a fancy house in a city. It is a portable product meant for use in remote areas, by soldiers no less, far away from working cellphone towers or reliable power supplies. Serious consideration should be given before attaching anything more complicated than an on/off toggle switch.
    - joshuaheard 4y ago
      I'm sure there is a manual override if your phone is dead and you have to walk over to activate it.
    - 4y ago
gargalatas 4y ago
20 watthours per liter of drinking water is not bad and it's way more efficient than the dehumidifiers. Looks like a great solution even at that slow production rate.

zubairq 4y ago

Amazing! Is this a game changer?

siruva07 4y ago
Maybe. I think Atmospheric Water Generators are much More likely to change the game since they don’t need a body of water other than the atmosphere.
- deleted 4y ago
  [deleted]
- stephen_g 4y ago
  There are big thermodynamic problems with those, the phase transition requires a lot of energy... Generally the main places where they work with any kind of acceptable efficiently and decent yield (where there's high enough humidity) are also the places where it tends to rain a lot!
- MichaelApproved 4y ago
  “Atmospheric Water Generators” At first I thought you were just using a marketing term for dehumidifiers but I looked it up before posting. I see that term is used for tight mesh fabric that’s hung vertically as a passive matrix to collect condensation. While those are actually game changers, they unfortunately only work in special regions that have the needed weather and topography to make them work. I think there’s only one place on earth that has the perfect combination for AWG: weather, drought, and humidity. It’s an awesome technology for them but that’s about the extent of it. I’ll try to find the region and update my comment with more info. Edit: here’s a video that talks about what I think you’re talking about. https://youtu.be/YxRONAZoMDk https://youtu.be/YxRONAZoMDk It’s providing water in the Atacama Desert near Lima Peru. Edit 2: They’re called fog collectors and apparently Morocco uses them too. https://youtu.be/0F7CQMd6mQ4 https://youtu.be/0F7CQMd6mQ4
  - fiddlerwoaroof 4y ago
    I wonder if you could use a similar sort of device with weather balloons to harvest water from clouds.
    - kortex 4y ago
      I could totally see a Project Loon style craft which automatically surfs the crosswinds, going up above the clouds to radiate heat to the open sky at night, and descending to condense water.
    - MichaelApproved 4y ago
      Would dry regions that need water have enough cloud coverage for that to be viable? My guess is that any place with sufficient cloud coverage is already getting enough rain water to satisfy their needs.
      - fiddlerwoaroof 4y ago
        I think there are parts of coastal California where there are clouds more of the year than rainfall. I'd also suspect if you just raised them up with balloons to cool them off and then brought them down where it's warmer, you could condense evaporation from the ocean, without spending energy directly on cooling.
        MichaelApproved 4y ago
        You’d have to raise them up pretty high to get them colder than the dew point. The energy it’d take to raise and lower the material would make it cost prohibitive. I considered that the balloons would be a balancing force but don’t forget the rope length changes as the balloons go up and down. That changing length shifts the weight around. You can’t be balance against it.
  - FR10 4y ago
    > It’s providing water in the Atacama Desert near Lima Peru. I think one big issue is that in winter (May-September) not every day is foggy, so sure its helpful but not a perfect solution. It does get really foggy though in June-October. Thus we get natural vegetation in otherwise arid hills around Lima, the most popular called Lomas de Lachay[0]. [0] https://en.wikipedia.org/wiki/Lachay_National_Reserve https://en.wikipedia.org/wiki/Lachay_National_Reserve
qayxc 4y ago
Probably not. It's more expensive than available alternatives (according to the article they use expensive materials) and the performance is poor compared to commercially available alternatives. Might be useful for certain niche applications, but outside of that it's more of a proof of concept at this point.

nullc 4y ago

So how is this distinguished from existing commercially available continuous electrodeionization?

qayxc 4y ago
Uses less power and is portable? That's pretty much all I could gather from the article.
- nullc 4y ago
  That's its claimed advantages against reverse osmosis.

MichaelApproved 4y ago

Edit: I wrote out the comment below criticizing the efficiency of this device, when compared to reverse osmosis RO desalination (100x less efficient). However, they’re not trying to be more efficient than RO devices, they’re trying to be more compact, portable, and avoid the need for filters. They’re solving for a different problem than I was measuring them against. In my race to criticize, I overlooked those key details. I still think my comment is worth reading to learn about the efficiency differences but I guess that measurement is not important for the viability of this technology. Original criticism below: ——————— I’m skeptical about how practical this actually is. While it’s refreshing to see a drinking water solution that isn’t based on inefficient dehumidifier technology, this still seems impractical. From the demonstration video, their portable ~50 watt solar panel took 30 minutes to get a few ounces of drinking water. It looked like a cold winter day, so let’s be generous and assume the panel only produced 15 watts of power during those 30 minutes. Let’s also be generous and say they got 5 ounces of water. That means they produce 1 ounce of water for every 3 watts. That’d be 333 ounces per kWh. To put that into perspective, a desalination plant produces more than 100x that much. Yes, there is lots of additional infrastructure to consider with a traditional desalination plant but It’s not like this solution wouldn’t require the same complexity to scale up. I don’t remember the cost of dehumidifier drinking water “solutions” but I think this is slightly more efficient than those horrifically inefficient solutions.

tomxor 4y ago
From the article it sounds like they are looking for ways to scale down (i.e small portable units are the target form factor, not a mere demo), and this is where it compares favourably against things like reverse osmosis for efficiency.
- MichaelApproved 4y ago
  I was so quick to criticize technology that I completely overlooked those points. Reading the article again, it’s embarrassing to see that I missed it when they were emphasizing it so much. I have one more lingering criticism that I don’t think they addressed (I reread it twice). What happens to the salt after it’s removed? If they don’t have a filter, where does it go? Do they pump brine water back?

nkingsy 4y ago

From the article: The limitations appear to be expensive materials and scale. 20w per liter .3 liters per hour

MichaelApproved 4y ago
The article claims 3x more efficiency in a confusing sentence: ”Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watts of power per liter.” So the unit only produces 0.3 liters an hour but if you wait 3 hours and provide 20 watts of power (7watts/hour), you’ll have a full liter.
- qayxc 4y ago
  > So the unit only produces 0.3 liters an hour but if you wait 3 hours and provide 20 watts of power (7watts/hour), you’ll have a full liter. That doesn't make any sense. 20W of power draw over 3⅓ hours is ≈67Wh (Watthours, not Watts per hour), so 67Wh per litre (energy use; independent of time) and it takes 3⅓ hours to get this litre of potable water with 20W of power. In other words to get 1 litre in an hour, the device might require ≈67W of power (assuming that kind of perfect scaling is even possible with their design).
  - BeefWellington 4y ago
    The wording in the article is specifically: > requires only 20 watts of power per liter. Whether the article is accurate or not I think you missed that.
    - qayxc 4y ago
      The point is that 7W/hour is nonsensical. It's a non-unit and physically doesn't make sense in any context. The power is independent from the volume. Total energy use is volume dependent. 20 Watts per litre is mix of units that's nonsensical. Watt is Joules (Energy) per second (time), i.e. power. Either time is irrelevant, that is the device draws 20 Watts of power, in which case you can ditch the litre. Or the power draw is dependent on the performance in that more power equals higher throughput. Neither case is in any way shape or form correctly described by "20 Watts per litre". Hope that makes it clearer now.

photochemsyn 4y ago

If this unit is shown to be durable, I imagine it's the kind of thing a lifeboat would have as part of its equipment. Low power means low volume of drinkable water (as energy is needed to separate ions from seawater, by the laws of entropy), so that's really unavoidable with this system. Compare to things like concentrated solar for complete removal of solids from wastewater and seawater, here's an interesting example (relies on condensation of steam): https://influencing.com/pr/99083/novel-solar-powered-water-treatment-tech-awarded-100-000-in-australian-innovation-grants https://influencing.com/pr/99083/novel-solar-powered-water-t...

Stevvo 4y ago
This thing is going to cost more and be far less capable than a traditional suitcase or even hand-pump desalinator and you never see those on lifeboats.

dehrmann 4y ago

> The suitcase-sized device...can also be driven by a small, portable solar panel, > Yoon and Kang used machine learning to find the ideal combination of ICP and electrodialysis modules. These bits feel like they were added because ML and solar power will get more clicks.

eps 4y ago
> The research was funded ... the Experimental AI Postdoc Fellowship Program of Northeastern University, and the Roux AI Institute That's the cause of the AI part. The solar panel bit probably came from the Army requirements, who's another sponsor.
SturgeonsLaw 4y ago
True, especially using ML to determine the size/layout of the components. That could be very easy assessed by varying the sizes in a consistent, linear way, and measuring the effectiveness in subsequent tests, rather than throwing it into the black box of ML.
SamBam 4y ago
ML maybe, but solar power definitely not. They show an example use-case as a single-family house in a site of flooding and devestation. An emergency desalinator would definitely need to run off of a small generator or solar.

gonzo41 4y ago

This is a pretty cool development, even if they made this thing the size of a 20ft shipping container it'd be a pretty good development.

kylehotchkiss 4y ago

Southern California is beginning to see more water restrictions - each and every desalination tech advancement is a very hopeful development for the region, and many others in the world that can't get enough freshwater. I hope they can generally work this up to factory scale and put it behind a solar farm and see if that can supply a lot of homes.

KennyBlanken 4y ago
The problem is that southern California is trying to grow a shit-ton of crops that aren't suitable for the environment there. The almond industry is particularly guilty in this regard. Desalination will never scale to a level suitable to supply that industry. If anything they'll take that water and just grow even more crops, while still sucking the aquifer dry. Thing is, aquifers compact when you draw water from them too much. That compaction can never be undone. They are slowly rendering that land permanently uninhabitable.
- qayxc 4y ago
  > Desalination will never scale to a level suitable to supply that industry. Are you sure about that? It's simply a question of economics. As long fresh water from other sources is significantly cheaper, no one's going to invest in large scale desalination. Once this changes it becomes a question of which is more expensive - shutting down the agribusiness or running large scale desalination (which has options, from nuclear to solar to the use of metamaterials).
  - sp332 4y ago
    It is true in California, because you need to dump the concentrated brine somewhere, and doing that at industrial scale will run up against environmental protections.
    - jillesvangurp 4y ago
      There's a big bucket right next to California called the Pacific. Perfect place for sourcing water to desalinate and dumping brine back into without doing anything measurably harmful to salt concentrations in the Pacific. It's like a literal drop in the ocean. Most big Californian metropolitan areas are right next to it. There is no water shortage; just a reluctance to pay a fair price for it. The challenges in California are not technological but political and policy related. Local consumers of water seem to assume that water is like manna from heaven that has to be perpetually subsidized by the government. They feel entitled to it but are not really willing to pay for it; or even invest in common sense ways to reduce their consumption of it because it doesn't really cost them anything.

KennyBlanken 4y ago

If I had a dollar for every project MIT's press office has said will be revolutionary and end (insert major world health/water/resource/energy/food problem), I'd be a very, very rich person. I'm not sure why MIT's press office gets so much favor here, particularly given their/MIT's track record. Post articles by science journals and news outlets that will tell us if this is actually going to work or if it's just yet another go-nowhere project.

swader999 4y ago
At least this instance has a workable demonstration. Looking at you battery tech...

yyyk 4y ago

I recall similar in function devices already existed for military use - except they made water from air, which is even more available than seawater: https://www.honeywell.com/us/en/press/2021/05/honeywell-led-team-creating-a-portable-device-that-extracts-drinking-water-from-air https://www.honeywell.com/us/en/press/2021/05/honeywell-led-... https://edition.cnn.com/2014/04/24/tech/innovation/machine-makes-drinking-water-from-air/index.html https://edition.cnn.com/2014/04/24/tech/innovation/machine-m...

aemreunal 4y ago
Fun fact, there's vodka made from San Francisco fog: https://time.com/4317269/fog-vodka-san-francisco-hangar-one/ https://time.com/4317269/fog-vodka-san-francisco-hangar-one/

mothsonasloth 4y ago

What about filtering particles which don't have a charge like plastics or biological matter? I guess you can always just boil the water after it's been processed by the portable machine.

eps 4y ago
I didn't quite get this part either - > The membranes repel positively or negatively charged particles — including salt molecules, bacteria, and viruses ... Are bacteria and viruses indeed electrically charged? This sounds strange.
- beanjuice 4y ago
  Yes [0], "Bacterial cell surfaces possess net negative electrostatic charge by virtue of ionized phosphoryl and carboxylate substituents on outer cell envelope macromolecules which are exposed to the extracellular environment." [0] https://doi.org/10.1016/S0167-7012(00)00224-4 https://doi.org/10.1016/S0167-7012(00)00224-4

timonoko 4y ago

Those specifications are much worse than 30 year old PUR-06. It makes one liter per hour with 20 Watts and fits in your pocket. I tried solar panel and windshield wiper motor. But direct-drive windmill was much better as wind blows 24/7 on Baja. https://youtu.be/9xYXWISWv5I?t=390 https://youtu.be/9xYXWISWv5I?t=390 Durability was the issue. I destroyed three units and average was 200 days / 1000 liters, because all-plastic construction. Found no limits on filter durability.

timonoko 4y ago
I was planning to make those crucial breaking parts from Carbon Fiber myself, but I was such a poster-boy for PUR that they sended me free PUR-35 ($5000). It makes 3 liters per hour and if you replace the solid-iron pumping shaft it weighs about a kilo. Except one crucial high-pressure valve cannot be made of plastic. I made better one from fiber glass. Thereafter it been running ok for 20 years.

Simon_O_Rourke 4y ago

If this works the way it looks like it does, these devices will be a literal life saver. Would love to see a buy-one-donate-one purchase plan.

yellow_lead 4y ago

Anyone else notice in the beach video that the researcher filled the cup using tubing that was previously on the ground, then drank it? Looks cool though :)

netsharc 4y ago
He did wipe the sand off the output tubing... good enough? I guess if I dropped a drinking straw on the ground in an e.g. parking lot, I'd throw it away, but if I dropped it on sand in the beach, I would think "just wipe the sand off and it's clean!"
- xtracto 4y ago
  Back in the day when I went camping with my parents we used to "wash the dishes" using seawater and sand from the beach. Nowadays people are unnecessarily germophobic.

denton-scratch 4y ago

> requires only 20 watts of power per liter. So if you want a liter, you have to supply 20 watts. For how long? Forever? Does the water instantly become turbid when power is removed? Tsk, tsk, MIT. I would have thought an MIT journo would know what a watt is.

soVeryTired 4y ago
> Their prototype generates drinking water at a rate of 0.3 liters per hour, and requires only 20 watts of power per liter. Not great phrasing I agree but the information is there.
- qayxc 4y ago
  Nah, still doesn't make any sense either way. Watts is a measure of power, not energy. The amount of power (given they use a pump and electrodialysis) shouldn't depend on the volume. Energy OTOH does. So either their device requires 20W of power - which sounds reasonable as the image shows a <100Wp solar panel next to it - and the volume figure is meaningless. Or the author left out crucial context (e.g. is the power draw correlated with the speed, i.e. 20W @ 0.3l/h). The amount of energy would be 67Wh/l regardless given those numbers. It's just a confused mix of performance (processed volume per hour) and power requirements (which is independent of volume and should only depend on the performance).
- denton-scratch 4y ago
  The trailing "per liter" seems the problem: I think maybe what they mean is that 20W gets you 0.3 liters per hour? So their machine produces 0.3 liters per hour, and draws 20W? I wish journos wouldn't bandy around terminology and statistics they don't understand. It's getting worse.
  - SamBam 4y ago
    It isn't, though, because that would be 60Wh per liter, but the video actually specifies it's 20Wh per liter. They just stupidly used watt instead of Wh in the article text.

JoeAltmaier 4y ago

With advances, perhaps one day it will be the size of a pack of cigarettes. And thus portable enough to include in an emergency kit!

smiley1437 4y ago

Am I reading this wrong? It uses less energy at higher production rates? This is a verbatim copy of the text at 1:32 in their video: Seawater >> Drinking Water ~ 20Wh/L for 0.3L/h of production rate ~ 15Wh/L for 1.0L/h of production rate so it uses LESS energy to get MORE drinkable water per hour? That seems odd.

davelondon 4y ago
I assume this means with a larger device...
- smiley1437 4y ago
  Okay that makes sense
SamBam 4y ago
They show that the 1L/h version uses more elements. I assume there are some efficiencies as you get larger.

davelondon 4y ago

Not sure this is better than reverse osmosis... They mention ~15Wh/L @ 1L/hr... The Katadyn Powersurvivor 40 (pretty compact and 11kg) uses 8.5Wh/L @ 6L/hr... https://www.spectrawatermakers.com/us/us/89650-8013438-Katadyn-Powersurvivor-40-e-12-V-a https://www.spectrawatermakers.com/us/us/89650-8013438-Katad...

sp332 4y ago
Once an RO filter gets clogged, it stops working.

sandworm101 4y ago

>> The researchers also created a smartphone app that can control the unit wirelessly and report real-time data on power consumption and water salinity. No no no no. I was all onboard with this seemingly wonderful product until I hit that line. The things that provide fresh water, that actually enable life functions, should NEVER involve controller aps. Switches. Dials. Positive on/off switches. Maybe the occasional touchscreen. But please do not put the need for a working/charged/connected cellphone between the user and their source of fresh water. And they say that this thing uses about as much power as a cellphone charger. Wrong. It requires the power of a cellphone charger to filter water, plus a second charger to power the cellphone running the app.

joshuaheard 4y ago
A cell phone app would be handy for remote monitoring and control. Say you lived a mile away from the ocean where it is deployed. You could turn it on and off depending on the tide and know when the container you are filling is full. Having just completed a home remodel where all the home automation features have an app, having apps is a handy way to monitor and control your hardware without leaving your couch, or even if you are off-premises.
- sandworm101 4y ago
  But does the pipe bringing fresh water into your house use an ap? There are things in this life that are expected to "just work", that are so basic they should not be trusted to aps. This product isn't for a fancy house in a city. It is a portable product meant for use in remote areas, by soldiers no less, far away from working cellphone towers or reliable power supplies. Serious consideration should be given before attaching anything more complicated than an on/off toggle switch.
  - joshuaheard 4y ago
    I'm sure there is a manual override if your phone is dead and you have to walk over to activate it.
  - 4y ago

gargalatas 4y ago

20 watthours per liter of drinking water is not bad and it's way more efficient than the dehumidifiers. Looks like a great solution even at that slow production rate.