A simple device that can capture its own weight in water from fresh air and then release that water when warmed by sunlight could provide a secure new source of drinking water in remote arid regions, new research from KAUST (King Abdullah University of Science & Technology) suggests.
At the heart of the device is the cheap, stable, nontoxic salt, calcium chloride. This deliquescent salt has such a high affinity for water that it will absorb so much vapor from the surrounding air that eventually a pool of liquid forms.
The full research paper is available on-line.
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Drinking Water Sucked from Dusty Desert Air Using Hybrid Hydrogel
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(Score: 5, Insightful) by Runaway1956 on Sunday December 09 2018, @01:12PM (11 children)
There have been several stories about pulling water from the atmosphere, in the past year or so. That's cool and all, but, how does that fit into the big picture? Isn't the net effect to make the area yet more arid?
Pulling your drinking water from the air is really cool - even I could probably survive in a desert if I'm carrying something like that. But, won't it make a whole lot more sense to desalinate ocean water, and pump it into the desert? With that, you're reclaiming desert land.
To me, it looks like this is good, or very good, but people could spend their time and effort a little more wisely. Opinions?
(Score: 2) by takyon on Sunday December 09 2018, @01:19PM (2 children)
We should be using desalination with graphene. Much of the world's population lives within a couple hundred kilometers of a coast.
Y Combinator Unveils Another Climate Change "Moonshot": Flood a Desert [soylentnews.org]
Congrats, you think like a venture capitalist.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by Immerman on Sunday December 09 2018, @04:37PM
Yep, which is why it's great that MIT has worked out a roll-to-roll process to produce high-quality graphene sheets at industrial scales. http://news.mit.edu/2018/manufacturing-graphene-rolls-ultrathin-membranes-0418 [mit.edu]
I'm really looking forward to the things industrial-scale graphene will make possible.
I'm also wondering if this roll-to-roll process creates long thin strips of continuous graphene, and if so, how the strength and durability of a strip of rolled-up graphene compares to a multiwalled carbon nanotube.
(Score: 3, Interesting) by realDonaldTrump on Tuesday December 11 2018, @02:43AM
Beautiful Clean Coal is our answer to Climate Change, otherwise known as the Global Warming. And it's our answer to many things. Because Clean Coal from West Virginia is a great source of Graphene. Big thanks to our West Virginia Clean Coal miners!!
(Score: 0) by Anonymous Coward on Sunday December 09 2018, @01:29PM
Desalination is a good idea, but it is expensive, has high energy requirements, and the water needs to travel hundreds (or thousands) of miles to get to everyone who needs it.
This isn't intended to replace desalination. It's a very low cost, low energy solution that works where the water isn't. Maintenance on this is basically nonexistent.
(Score: 1, Funny) by Anonymous Coward on Sunday December 09 2018, @01:57PM (1 child)
you pull the water from the air, then drink it and then it ... vanishes.
duh, obviously not. you pee it out after it has lubricated your body and then *poof* it evaporates leaving behind all the
crap your body doesn't want to use anymore.
it think the only way to dehumidify the global air pool is to pull lots of water from the air, make ALOT of meatbags VERY VERY
quickly, pour water into them so it is contained and cannot return to the air :P
(Score: 3, Funny) by Runaway1956 on Sunday December 09 2018, @02:17PM
Point taken. It's like a beer - you can't buy it, you can only rent it. You can't even sign a long-term lease on it, just short term rental.
(Score: 1, Interesting) by Anonymous Coward on Sunday December 09 2018, @02:08PM (1 child)
Set up a chain of nuclear (or renewables if the capacity wasn't cost prohibitive) power plants going from the california coast, across nevada, to Utah. Rather than desalinating the water, just sterilize it for foreign microbes then pump it up into the great salt lake basin and the nearby lakebeds in Utah and Nevada, including the areas surrounding the bonneville salt flats. With the continually renewing source of saltwater brine the local ecology would become more humid, there would be a renewable source of salt without eroding the salt flats, and there would be an increase in freshwater in the water table as a result of the dedesertification of the nearby regions thanks to the continual influx of new water to promote more plant life.
This covers industry, environment, public benefit, and special works porkbarrel projects all in one. It seems like it should be a sure win to blow through Congress.
(Score: 0) by Anonymous Coward on Sunday December 09 2018, @02:15PM
I kinda like your idea. Let's flood Salt Lake City. That will teach those Mormon heretics!
(Score: 0) by Anonymous Coward on Sunday December 09 2018, @02:26PM
clouds do fly over the deserts, and there is limited mixing of the different layers of air.
it sometimes rains over a desert, but the water droplets evaporate before they hit the ground (this is especially fun in US deserts, where sometimes the mesa formations get wet on top, but everything else around them stays dry).
in any case, if you remove water from the air while it's going over the desert, there are ways for the water vapor concentration to go back up to the ~20% or whatever it is in that particular desert: ultimately, it will rain less wherever those desert-passing clouds did turn into proper rain.
(Score: 2) by legont on Sunday December 09 2018, @05:21PM
Just a note that hot desert air contents a lot of water - a lot. The water vapor amount in the air is directly proportional to the temperature and the driest air is over antarctic ice.
If this works, it is very useful indeed.
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 2) by JoeMerchant on Sunday December 09 2018, @06:25PM
Tell that to the native desert species you just destroyed.
OTOH, I agree with you, pulling the little remaining residual moisture from the desert air does seem likely to upset the ecological and perhaps even geological (think: killer dust storms) balance, if done on a massive scale - such as to feed a subdivision with water. Now, you might argue that the subdivision is only borrowing the water and will give most of it back via their treated sewage, sprayed onto municipal golf courses and re-evaporated into the air, but the distribution is going to be quite skewed with unnaturally high humidity around all the mouth breathers in their fuel burning SUVs, and lower than historic humidity near the moisture farms.
-----
Uncle Owen: Well, he'd better have those units in the South Ridge repaired by midday, or there'll be hell to pay.
🌻🌻 [google.com]
(Score: -1, Flamebait) by Anonymous Coward on Sunday December 09 2018, @01:41PM
after we've liquified them. #khashoggi
Or just crash air planes into twin towers while sipping Evian and cozying up with Mr. Kushner.
(Score: 2, Insightful) by jbruchon on Sunday December 09 2018, @01:51PM (7 children)
You can't get enough water from the air in a DRY DUSTY DESERT to be meaningful. That's why it's "dry." This has been tried countless times already, with glorified dehumidifiers to condense and collect water being the most popular design. They work great in a humid climate because there's no shortage of water anyway, but in an arid climate there's little water vapor to collect in the first place. This is getting old.
I'm just here to listen to the latest song about butts.
(Score: 5, Informative) by martyb on Sunday December 09 2018, @03:22PM
From the research article [acs.org] linked in TFS:
RH == Relative Humidity
AWG == Atmospheric Water Generator
Wit is intellect, dancing.
(Score: 2) by legont on Sunday December 09 2018, @05:28PM (3 children)
Where is more water in the air - in Death Valley or in NY City? Death Valley has way more (because it is hotter).
"Wealth is the relentless enemy of understanding" - John Kenneth Galbraith.
(Score: 2) by JoeMerchant on Sunday December 09 2018, @06:30PM
Exactly this... and, there are deserts with quite a bit of humidity but little condensation, like the Atacama that the BBC is always prattling on about.
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Monday December 10 2018, @03:54AM (1 child)
"Death Valley has way more (because it is hotter)."
Show me the numbers. Your "it's hotter" claim ignores hundreds of other factors which affects water density of the air.
(Score: 1) by nitehawk214 on Monday December 10 2018, @03:17PM
It also probably does not average it over the year. Sure, its fucking cold in New York City in December, but it is also 100 degrees in July.
"Don't you ever miss the days when you used to be nostalgic?" -Loiosh
(Score: 2) by JoeMerchant on Sunday December 09 2018, @06:28PM
It's all a question of scale and density. There is moisture in the desert, enough to support X people per square mile (X varies with both the specific desert region in question and the style in which the people intend to live...)
For that matter, there's moisture on Mars - maybe not enough to support 10 million people on the whole planet (until we crash a couple of water-comets on it), but this kind of technology might assist in collecting water in such conditions.
🌻🌻 [google.com]
(Score: 1, Interesting) by Anonymous Coward on Monday December 10 2018, @09:57PM
This yet-another-free-water-from-air-machine is also a glorified dehumidifier. However instead of a heat pump style dehumidifier, this is a dessicant dehumidifier. Such systems certainly work, you can buy them on Amazon.
On Earth the dry air will still have water vapour so it's "merely" a matter of scale, you must process correspondingly more air to get the similar amounts of water out, which in practice probably means a larger facility. That's a problem in its own right but it's probably not an insurmountable problem with the concept. Nevertheless, there are major problems with the concept of using dessicant dehumdifiers as a drinking water source.
Most obviously, dessicants normally are extremely toxic—I doubt this one is any exception—which is why when you find things like silica gel in product packaging it has a big warning on it saying "DO NOT EAT, THROW AWAY". Yeah, just what you want mixed in your drinking water supply. So you will need to treat the output of the process anyway, and then one quickly realizes that access to liquid water in the world is not really a problem humanity needs to solve; access to safe water is.
The more serious problem is that dessicant dehumidifiers don't do anything to avoid the thermodynamic implications of condensing water. There is no way around it: turning liquid water into water vapour involves putting a very large amount of thermal energy into that water (about 2.2MJ/kg), and the reverse is exactly the opposite: you must take all that energy back out (i.e., about 2.2MJ/kg must be removed from the water vapour). In the case of a dessicant this involves some sort of chemical interactions so it's maybe not as simple to think about as a heat pump, but essentially all the energy input to actually make this work happen will be in the processing of the reagents.
As usual, it will be substantially cheaper and easier to load up a fleet of 50 tonne tanker trucks with potable water sourced from a lake halfway around the world and drive it wherever you need the water than it will be to use "free" water from air machines for drinking. That's why these systems are invariably stupid: it is just too energy intensive (-> expensive!) to condense water for the purpose of drinking it.
(Score: 1, Interesting) by Anonymous Coward on Sunday December 09 2018, @07:48PM (1 child)
I saw a documentary where they rasied such a tower in a village with a simple bamboo skeleton and polyester threads which would give 100 liters of water per day.
Seems much simpler.
http://www.warkawater.org/ [warkawater.org]
(Score: 2) by JoeMerchant on Monday December 10 2018, @12:47AM
Warka tower (makes me think of the Wonkatania [youtu.be], is very cool for making potable water in a place where bamboo is readily available...
Unfortunately, there's not much bamboo in the desert, and the polyester thread method probably doesn't work in lower relative humidity conditions.
🌻🌻 [google.com]