New Water Desalination Device Runs on Solar Energy and is 400% More Efficient:
An international team of researchers including engineers from Ural Federal University (UrFU) developed a new desalination technology with high-efficiency thanks to a rotating cylinder, a press release reveals.
[...] The method utilizes a cylinder that is slowly rotated by a solar-powered DC motor. The rotating hollow cylinder is housed inside a rectangular basin that acts as a solar distiller. This cylinder accelerates water evaporation in the vessel by forming a thin film of water on its outer and inner surface. The film of water is constantly renewed with each turn of the cylinder, while the water below the cylinder is heated using a solar collector.
The team tested a prototype on a rooftop in the Russian city of Ekaterinburg for several months in 2019. They found that at 0.5 rpm, the machine would allow the evaporation of a thin film of water from the surface of the cylinder.
"The performance improvement factor of the created solar distiller, compared to traditional devices, was at least 280% in the relatively hot months (June, July, and August) and at least 300% and 400% in the cooler months (September and October), at the same time, the cumulative water distillation capacity reached 12.5 l/m2 per day in summer and 3.5 l/m2 per day in winter," said Alharbawi Naseer Tawfik Alwan, a research engineer at UrFU.
Journal Reference:
Naseer T. Alwan, S. E. Shcheklein, Obed M. Ali. Evaluation of distilled water quality and production costs from a modified solar still integrated with an outdoor solar water heater [open], Case Studies in Thermal Engineering (DOI: 10.1016/j.csite.2021.101216)
(Score: 3, Interesting) by Tork on Tuesday August 03 2021, @05:18PM (17 children)
I dunno why but I find improvements like that really fascinating. I'll never know if it'll ever be useful to me but I feel like my own metaphorical toolbox got a little bigger just reading that.
🏳️🌈 Proud Ally 🏳️🌈
(Score: 5, Insightful) by JoeMerchant on Tuesday August 03 2021, @05:25PM (15 children)
Like so many solar projects, to me the ultimate question of efficiency comes down to: how easy is this thing to keep clean and functioning?
Just because the energy input to evaporate water is tiny, or negligible, if you've got to scrub the thing down with acid every three months to keep it working how efficient is it, really?
🌻🌻 [google.com]
(Score: 1, Insightful) by Anonymous Coward on Tuesday August 03 2021, @06:58PM (2 children)
TFA does not even explain what the "traditional device" they are comparing against to get their 400% improvement. I imagine they must be comparing with some other distillation technique. There are no actual performance numbers which could be used to make your own comparisons, you'll just have to take their word for it that it's Really Really Good™.
Distillation is normally a pretty bad way to go about desalination. Evaporating water inherently takes a lot of energy (although some of that can in principle be recovered when the water is condensed again). Reverse osmosis is normally much more efficient as it does not involve evaporation at all. Basically all modern desalination facilities use reverse osmosis methods because of its much lower energy usage (although distillation is still used, mostly in older, uhm, "traditional" plants).
Moreover, practically any technique will "run on solar energy" -- all you need to do is power your machine with solar panels! The question is always "how much energy?" -- we care about how expensive some method is when compared to other methods (and, as mentioned, at an industrial scale the cost of keeping all the equipment working will be a significant consideration). We could speculate on the answers to these questions with actual performance numbers, but of course the article provides no insight.
As is so typical with science reporting, every paper has to be is pimped out as a fantastical solution to some huge global problem, probably because it works to secure more grant funding so everyone does it. I'm sure the scientists are researching cool stuff and discovering cool things. But these sort of articles are essentially just reporting on the fantasy bullshit and never on the actual cool thing that was done. We should just be happy there's not a crowdfunding campaign, I guess...
(Score: 2) by c0lo on Tuesday August 03 2021, @10:40PM
TFSciA [doi.org] is open-access and it does say what other designs were considered.
Reverse osmosis is not in the list.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Wednesday August 04 2021, @08:34PM
The fantasy writing is part of the deal now. You can't get a real job in science without being a grant-writing liar. At my uni, all the faculty are expected to go out and win grants at pitiful success rates. They don't do work, or anything useful. Just pound paper out that clogs up their counterparts in other institutes. This is the MBA model of research, that it is a profit center NOW and needs to justify itself ahead of time.
Nobody may ticker around generally improving things. Everything needs a mission and Leadership driving(tm) the process, ideally a Great Man that is too busy to talk to you.
(Score: 4, Funny) by edIII on Tuesday August 03 2021, @07:10PM (5 children)
On that note, I cannot remember where the article is anymore, but I swear there was a nano material able to do it against gravity. It's inherently able to desalinate, and clean pollution from water. The way it worked was channels only slightly bigger than the water molecule itself "captured" them and the motion of the water molecule was such that only forward movement through the channel was possible. It made me think of Jackie Chan kicking himself up a building or fence at one the corners.
We should be looking into technology like that because it accomplished two things. Only water molecules are transported away, and it lifts them to a higher elevation. I remember imagining towers of this material sitting in the ocean with pipes running to land providing both water and energy at the same time.
Recently there was another piece of technology developed that can easily turn falling water into electricity [siliconrepublic.com]. Thankfully, I kept the link for that. If you can move a large amount of water 1000ft up, I can see a tube ("like those rain sticks") that converts the energy of the falling water into electricity for 1000ft down multiplied by the diameter of the material. Considering that I saw 7 drops in a video powering a 100W string of LEDs, that is a considerable amount of power.
I want to know how to build that tower. Even on land, it's an endless supply of energy in a closed loop.
Technically, lunchtime is at any moment. It's just a wave function.
(Score: 4, Interesting) by JoeMerchant on Tuesday August 03 2021, @07:35PM
While nanomaterials can do some really cool stuff, like allowing water molecules through without allowing larger or otherwise pore-incompatible molecules through, and wicking has been "a thing" since forever, your perpetual energy generation towers are little more than the "dipping duck" evaporation powered systems. https://www.youtube.com/watch?v=Vvi3G_ZrcIo [youtube.com]
🌻🌻 [google.com]
(Score: 1, Insightful) by Anonymous Coward on Tuesday August 03 2021, @07:40PM (1 child)
Pretty sure over a longer length there would be a buildup of resistance such that ocean waves and molecular motion wouldn't be able to push more molecules upwards. Maybe it could go up to 1000ft, maybe not, but the idea is still cool and seems feasible.
(Score: 2) by c0lo on Wednesday August 04 2021, @04:54AM
Where's my "that's either incredibly stupid or redundantly funny" mod when I need it?
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by c0lo on Wednesday August 04 2021, @04:52AM (1 child)
(just in case there are people here able to believe injecting bleach and shining an UV lamp up the asshole could work and not getting the subtle tone of sarcasm in the post)
There ain't no such thing like a free lunch.
Once the water reaches the top of the nano-wick, it refuses to go further because the wick wants to keep it in place by the same forces that absorbed the water in the first place. So, to get your fresh water back, you'll need to grab that handle handle attached to the water and pull it forcefully from there.
Or push it from behind. Hang on, we're already doing it, we call it reverse osmosis.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by edIII on Thursday August 05 2021, @06:32PM
Sounds reasonable, but that is not what I saw in the video. I very clearly saw water not just being wicked to the top, but a small flow of water. Really wish I could find the dang article. It was here on SN, I'm sure of it. I believe the forces involved were much different than what is found in a wick. I do remember that it had more to do with the motion of the water molecule and how the nanotubes were constructed.
Technically, lunchtime is at any moment. It's just a wave function.
(Score: 2) by Beryllium Sphere (r) on Tuesday August 03 2021, @10:12PM
I'd follow up that question with how it compared to the maintenance needs of semi-permeable membranes for reverse osmosis.
(Score: 3, Interesting) by c0lo on Tuesday August 03 2021, @10:44PM (4 children)
You imagine that the reverse osmosis keep working and working by magic without any maintenance?
RTFA and you'll see the thing that does the job is a cylinder made of a blackened mild steel sheet.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Interesting) by JoeMerchant on Tuesday August 03 2021, @11:25PM (3 children)
Yes, the type of maintenance is important. Blackened steel is nice, shouldn't be rusting (much), but how long does it spin before it's coated with gunk that needs cleaning and what's that process like?
🌻🌻 [google.com]
(Score: 2) by c0lo on Wednesday August 04 2021, @01:04AM (2 children)
Wash it for the most salts, use the same salt water as the input. Use vinegar for the calcium/magnesium carbonates deposits.
The problems that you listed are common for any desal method. So, everything being equal**, what exactly is your objection?
** I doubt that you are gonna clean a RO membrane as easy as a cylinder of blackened mild steel.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 4, Insightful) by JoeMerchant on Wednesday August 04 2021, @02:25AM (1 child)
Oh, RO really seems annoying to operate to me, and I'd bet the cost of disposal of the spent filter media is externalized / landfilled.
This could be the greatest desalinization method ever - but if there's a glass sheet capturing the vapor and letting the sun shine in, that's another surface to clean just like solar cells, and that cost of cleaning is rarely factored into the energy budget or cost estimates in the academic papers.
🌻🌻 [google.com]
(Score: 2) by c0lo on Wednesday August 04 2021, @02:32AM
Valid point.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by PinkyGigglebrain on Tuesday August 03 2021, @07:28PM
You might find the OTEC [wikipedia.org] interesting too. It can produce electricity and desalinated water using a 20 degree C temperature difference between deep sea water and warm surface water. There isn't any reason why the incoming warm sea water couldn't be heated using solar energy. Or just about any source of thermal energy, geothermal, waste heat from industrial operations, even the passive decay of spent nuclear fuel might be enough to operate a modified OTEC.
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 1, Insightful) by Anonymous Coward on Tuesday August 03 2021, @05:18PM (1 child)
What's the baseline for that 280%? Are the traditional devices 1% efficient? Because that would take it up to just 2.8% efficient and is not exactly something to be ecstatic about.
If you're going to be tossing around numbers, do it properly (aimed at the author of the article, not the mods of SN)...
(Score: 0) by Anonymous Coward on Tuesday August 03 2021, @07:30PM
"1% efficient" doesn't really make sense for desalination. The inputs are energy (which we can measure in joules) and seawater, and the outputs are freshwater (which we can measure in litres) and brine. When talking about efficiency we normally would care only about the energy input and freshwater output so the efficiency would normally be expressed in units of "joules per litre" or similar, not as a dimensionless ratio.
Of course TFA doesn't give any information here either.
(Score: 3, Funny) by DannyB on Tuesday August 03 2021, @05:19PM
Efficient is a measurement of how many fish can be removed from the water.
To transfer files: right-click on file, pick Copy. Unplug mouse, plug mouse into other computer. Right-click, paste.
(Score: 3, Informative) by HammeredGlass on Tuesday August 03 2021, @06:28PM (15 children)
https://www.circleofblue.org/2019/world/desalination-has-a-waste-problem/ [circleofblue.org]
(Score: 3, Funny) by Opportunist on Tuesday August 03 2021, @07:01PM (1 child)
Do what we do with crude oil waste, just dump it in the sea, nobody will notice.
(Score: 1, Offtopic) by DannyB on Tuesday August 03 2021, @07:51PM
All of SN's unused mod points end up in rivers, and eventually collecting in the sea. Nobody seems to notice.
To transfer files: right-click on file, pick Copy. Unplug mouse, plug mouse into other computer. Right-click, paste.
(Score: 3, Interesting) by edIII on Tuesday August 03 2021, @07:17PM
Use it as a . Maybe you could use it to create a brick, and then wrap the brick in carbon nanotubes. [materialdistrict.com]
Technically, lunchtime is at any moment. It's just a wave function.
(Score: 3, Interesting) by PinkyGigglebrain on Tuesday August 03 2021, @07:36PM (2 children)
put the salt back in the ocean, taking measures to ensure you don't raise the salt content in a small locality by an excessive amount. The water that is being removed ist going to magiacly vanish, it will find it's way back to the sea eventually.
Maybe we could start dumping it into the North Atlantic around the point where the deep sea conveyor [howstuffworks.com]starts heading down. It might help offset the fresh water being dumped into that area by Greenland's melting ice cap.
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 0) by Anonymous Coward on Wednesday August 04 2021, @08:37PM (1 child)
Humans needs to start training to drink salt water. If Charles Darwin was right, we'll soon be able to drink water directly out of the ocean with no need to desalinate.
(Score: 0) by Anonymous Coward on Thursday August 05 2021, @09:15PM
(Score: 2) by HiThere on Tuesday August 03 2021, @07:38PM (5 children)
Put it in a drying pond and then sell it as high priced "sea salt".
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by JoeMerchant on Tuesday August 03 2021, @08:14PM (4 children)
Gotta be some way to recycle the microplastics while we're at it...
🌻🌻 [google.com]
(Score: 2) by c0lo on Wednesday August 04 2021, @04:56AM (3 children)
And extract that lithium from the now concentrated brine.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by JoeMerchant on Wednesday August 04 2021, @12:43PM (2 children)
Careful there, without lithium in the water what's going to keep the sharks' mood stabilized?
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Wednesday August 04 2021, @08:40PM
The SSRIs and estrogen-mimics should keep the sharks docile.
(Score: 2) by c0lo on Wednesday August 04 2021, @10:21PM
Oxygen is what you want to use for sharks. See "Caves of the Sleeping Sharks in Isla Mujeres, Mexico"
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 1) by Ron on Wednesday August 04 2021, @02:19PM (2 children)
We obviously shouldn't put it back in the oceans. It causes problems there too.
What if we re-fill all those old salt mines and other deep-underground storage?
Transportation is a bitch. But we seem to move a lot of oil with no trouble.
(Score: 2) by HammeredGlass on Wednesday August 04 2021, @03:25PM
The only way we move a lot of oil with no trouble is with pipelines.
(Score: 0) by Anonymous Coward on Wednesday August 04 2021, @08:42PM
History shows the only way to move oil is with trouble.
(Score: 3, Interesting) by crafoo on Tuesday August 03 2021, @07:22PM (1 child)
Cool result. Solar powered reverse osmosis system produces more per day, easily, and can also be solar powered. If these are easy to flush and clean, and since they do not consume reverse osmosis membranes, it could be useful I guess. I imagine some really nasty scum grows in there though. I don't know, maybe you could shovel the scum out into a solar oven and eat it.
(Score: 4, Insightful) by PinkyGigglebrain on Tuesday August 03 2021, @07:47PM
Very true.
But the osmosis membranes are expensive and require a non-negligible pressure difference between input and outlet which makes the needed hardware more expensive as well.
This system may not have as high an output but it uses significantly less electricity and would be cheap to mass produce and distribute to areas that have ample currently undrinkable water, abundant sunshine, and not much electricity. Like most areas where desalination tech is really needed right now.
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 3, Informative) by ElizabethGreene on Tuesday August 03 2021, @07:44PM (2 children)
The paper is open access.
https://www.sciencedirect.com/science/article/pii/S2214157X21003798?via%3Dihub [sciencedirect.com]
The %efficiency comparison appears to be vs. the performance of a conventional solar still that uses flat plate collectors to heat the water to distillation temperature.
(Score: 2) by c0lo on Tuesday August 03 2021, @10:49PM (1 child)
Not quite. I wouldn't call "conventional" something described as
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by ElizabethGreene on Thursday August 05 2021, @07:55PM
You are correct; I was wrong. I don't know how I transposed flat plate vs. evacuated tube collectors. That's an order of magnitude difference in cost, complexity, and efficiency. Sorry about that.
It is notable that they compared it to a solar still vs. a conventional gas-boiling distillation apparatus. Usually when someone wants to make a big number efficiency headline they use the worst possible comparable.
(Score: 1) by fustakrakich on Tuesday August 03 2021, @07:49PM (2 children)
Can't we just condense that? It will save a step
La politica e i criminali sono la stessa cosa..
(Score: 2) by c0lo on Tuesday August 03 2021, @11:05PM (1 child)
In some circumstances (the water vapor near saturation), it will definitely work. But it this case the cloud seeding is even cheaper.
Otherwise, let me introduce you to Thunderf00t [youtube.com] and his busting [youtube.com] dehumidifiers [youtube.com] vapourware [youtube.com].
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 1) by fustakrakich on Wednesday August 04 2021, @01:17AM
:-) Yeah, well, you do need an icebox to condense the water vapor from the swamp cooler
La politica e i criminali sono la stessa cosa..
(Score: 1, Insightful) by Anonymous Coward on Wednesday August 04 2021, @03:15AM (3 children)
They have essentially rediscovered the drum humidifier, only instead of blowing air through it they are shining sunlight on it.
(Score: 2) by pdfernhout on Wednesday August 04 2021, @04:38AM (2 children)
There was a related system from around 1988 (or earlier) by Stella Andrassy (and implemented by Charlie Parker). Not exactly the same, but it was a still with a rotating drum which had a wicking material (although not explicitly a thin film that I knew of). Heat could be supplied by solar energy or an electric heater or other source. The idea was that the wicking material accelerated the evaporation -- perhaps indirectly through a thin film? Not sure how much her patents reflect the final variation.
And earlier version before the drum:
"US5001846A - Solar electric drying apparatus"
https://patents.google.com/patent/US5001846A/en [google.com]
I mentioned her work on the green site for a story a different "new" distillation system: https://slashdot.org/comments.pl?sid=19268003&cid=61559369 [slashdot.org]
The biggest challenge of the 21st century: the irony of technologies of abundance used by scarcity-minded people.
(Score: 3, Informative) by c0lo on Wednesday August 04 2021, @05:17AM (1 child)
Wicking works best for forced evaporation, by increasing the evaporation area. The drawbacks:
1. you need higher energy to evaporate the water from the wick - because the wick will want to keep the water inside
2. you will need to supply the evaporation energy in the form of hot air - because the wick will cool by he evaporation of the water and the thermal flux through the wick is inherently lower than for just a layer of water. Which means when the sun is gone, the installation using wicks will stop operating or will be operating at vastly reduced efficiency.
This one works purely by the temperature of the water that the rotating drum exposes over a higher (and microscopically smoother than a wick) surface. As such, it will work for a good time during the night if you keep a reserve of water heated during the day.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by pdfernhout on Friday August 06 2021, @01:41AM
Thanks for the informative and insightful reply!
The biggest challenge of the 21st century: the irony of technologies of abundance used by scarcity-minded people.