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Scientists create device that cuts desalination costs by 90%
- vavooom 7y agoWhat is the expected timeline for desalination technology? Even with continued investment all efforts have seemed to plateau at some point when costs and feasibility reaches a critical point.
- deagle50 7y agoIsn't feasibility a function of the cost of alternative options? If our current methods dry up, what is considered nonviable today suddenly becomes normal.
- thinkcontext 7y agoHow would reverse osmosis filtration (the dominant desal method) "dry up"?
- swampthinker 7y agoHe's referring to traditional sources of fresh water like aquifers, rivers, and lakes.
- barbecue_sauce 7y agoThe major issue with desalination as far as I can tell is that it produces toxic brine that proves problematic as far as disposal.
- aesh2Xa1 7y agoThat's a good point. All the salt and other solute needs to go someplace. As that stuff comes from the ocean one might suggest it goes back into it at a controlled rate. The biggest challenge I'd read about had been energy costs, so this headline appears to be great news.
- kardos 7y agoIf the toxic brine is purely the extracts from the ocean water, you can toss it back into the ocean (with appropriate dilution). If the toxic brine has a bunch of additives that are a byproduct of the desal, then this is indeed problematic. The article mentions that this method eliminates the need for chemical additives so this could be a pretty low-impact method of desal.
- ninkendo 7y ago> you can toss it back into the ocean (with appropriate dilution) ... what are you going use to dilute the brine? The water you just desalinated? What's the point then? Seems to me if your input is seawater, and your output is a separated-out set of {fresh water, saltier sea water}, and you put the saltier sea water back in the sea, you're going to create a localized concentration of high salinity, no? Seems kind of unavoidable to me.
- sachdevap 7y agoNot necessarily. You could mix it in processed sewage. Assuming processed sewage is appropriately disposed off in the sea at limited locations with precautions, this should work. One concern may be the sheer volume from desalination might overburden the sewage disposal.
- ortusdux 7y agoI've spoken with a few oceanographers about this and the brine can be easily pumped back into the ocean with very minimal impact as long as you are smart about it. The effluent from a normal desal system is only twice the concentration of the source seawater. The key is to place your plant so you can reintroduce the brine into a fast moving and deep waterway. One interesting ancillary benefit of having a source of brine is that it makes extracting desired minerals and elements from seawater much cheaper and easier. I have personally seen a system that extracts uranium from seawater. Current implementations yield yellow-cake at twice the market rate. There is ongoing work to tie it into a desal plant and bring that cost down. There is also work to combine it with lithium extraction.
- pacaro 7y agoThis presumably depends on what your water source is. If you are desalinating groundwater, then yes the brine is going to be an issue, for seawater less so
- mixmastamyk 7y agoYou can dump it on land to evaporate, then sell some and bury the rest.
- deleted 7y ago[deleted]
- ars 7y agoIsrael gets 40% of its fresh water from desalination https://en.wikipedia.org/wiki/Water_supply_and_sanitation_in_Israel#Seawater_desalination_(2000s) https://en.wikipedia.org/wiki/Water_supply_and_sanitation_in... Israel went from having severe water shortages if there was no rain (plus environmental damage from overdrawing lakes) to being perfectly fine. And the costs are not too bad either. Israel also is the world leaded by far in controlling water leaks, which helps reduce water demand, and they also reuse greywater for farming. Other places with water shortages could do the same.
- everdrive 7y agoWhere does the salt go when you desalinate? At a large enough scale, would we risk salting some area (or body of water) to death?
- barbecue_sauce 7y agoThat's the major issue with desalination. Dumping the brine byproduct back into the ocean is roughly equivalent of dumping other chemicals into the ocean, if not worse.
- AnimalMuppet 7y agoWhy worse? I'd argue that it's less bad, because the salt was already there. Now, it can still be just as toxic, and that has to be handled. But if properly diluted, then it should be equivalent to the ocean evaporating water, which happens constantly.
- bryanlarsen 7y agoAlso, the water created through desalination will end up back in the ocean eventually.
- noodle 7y ago> But if properly diluted That's the key phrase here. Obviously, if you dump it back into the ocean such that it actually does not impact local salinity levels, its fine. But that's also true for essentially anything dumped into the ocean - if you can manage the dumping of a toxic chemical such that it has no impact, wouldn't it also be fine?
- AnimalMuppet 7y agoNo. If I take saltwater from the ocean, and desalinate it, and put the salt back in the ocean, the salt was already there before I started. If I dump a toxic chemical in the ocean, the toxic chemical was not there before I started. Those are not equivalent.
- _Microft 7y agoThey seem to be using a fast moving rotor with holes in the backside of the blades that extract the steam from the cavity and then condense it. --- Links and related articles: University: http://www.sfu-kras.ru/en/news/22304 http://www.sfu-kras.ru/en/news/22304 Related paper: http://research.sfu-kras.ru/publications/publication/514080724-710372260 http://research.sfu-kras.ru/publications/publication/5140807... (doi: 10.1007/s11431-014-5631-0) List of articles of the mentioned researcher (Kulagin) is at http://research.sfu-kras.ru/publications/author/24184408 http://research.sfu-kras.ru/publications/author/24184408 (Nothing stands out on arXiv when searching for either desalination, cavitation or Siberian Federal University)
- murkt 7y agoDesalination research isn't pre-published on arXiv. There are ~300 articles on arXiv where desalination is mentioned, and ~18-20k articles in the world. There is even a journal called "Desalination". I've found 64 articles total that mention "desalination AND cavitation", starting from 2006.
- this_was_posted 7y agohttps://sci-hub.tw/https://www.sciencedirect.com/science/article/abs/pii/S0011916418313912 https://sci-hub.tw/https://www.sciencedirect.com/science/art... I think this paper is relevant
- robocat 7y agoSo you can suck the gas vapour through the back of the rotor blade, so long as the rotor velocity is not exceeding the sound velocity of the gas? It seems like you could make one at home or maker workshop with a hollow shaft...
- ars 7y ago90% compared to heating. But at scale no one desalinates by heating, it's all membrane based. I'd like to see an energy comparison to that.
- LegitShady 7y agoexactly this
- bluGill 7y agoNo citation, but from what I've heard in previous discussions heat and membranes need about the same energy input. With heat you use the steam in heat exchangers so you recover most of your input heat and only need to add more to make up for inefficiencies (the system of course is never 100% efficient). With membranes you need to supply power to the pumps to keep the membranes at the correct pressure differential. The above assumes engineering went into designing an efficient system. Pumps are easier to make efficient, but at scale they are not necessarily better.
- russdill 7y agoThere's already a factor of 10 cost difference between different heating technologies given energy costs and mineral content in the water.
- darksaints 7y agoMembrane-based technology has already cut costs significantly over distilling, and it is already commercially mature. It would be more interesting to compare the costs of this to membranes.
- ortusdux 7y agoSomething like this tech would make for a great pre-filter that would greatly extend the life of membrane systems. The last membrane system I saw required extensive rejuvenation of the membranes annually.
- excalibur 7y agoIt's probably a good idea to develop more than one commercially-viable method regardless.
- dangerboysteve 7y agoIsrael has been using the membrane process for some time. I think their only issue how is dealing with the brine waste water.
- mehrdadn 7y agoWhat do they currently do with it?
- ori_b 7y agoDump it in the ocean? It's not like we're extracting water in sufficient quantities to affect the salinity of the Mediterranean.
- SAI_Peregrinus 7y agoThe issue there is with the mixing rates. While we won't affect the overall average dumping will create local zones of increased salinity, which can be a problem.
- m463 7y agoI remember reading the problem is that the salinity of the local dumping area rises sharply (maybe killing marine life)
- ncr100 7y agoHow could this impact political problems? My understanding of the Golan Heights and Israel vs Palestine is that it's about water. Will this technology help with that problem?
- LegitShady 7y agoits not really about water. this will help alleviate water problems in coastal areas - israel already desalinates water but making it cheaper is better. But the issue is far more complex than just water and the scope of this technological fix will not really affect it.
- ars 7y ago> My understanding of the Golan Heights and Israel vs Palestine is that it's about water. It's not. Golan Heights has nothing to do with Palestinians, and is about Israel not being shelled from mountains. Israel vs Palestine is about land, not about water. > Will this technology help with that problem? Israel already gets 40% of its water from desalination (see my post elsewhere in this thread). So been there done that :) Israel also works with Jordan on water issues, so they are using water as a kind of water diplomacy.
- shahar2k 7y agoit'll definitely help, israel already uses a massive percentage of it's electric generation to desalinate water. (since the country grows quite a bit of its own food) from wikipedia "By 2014, Israel's desalination programs provided roughly 35% of Israel's drinking water and it is expected to supply 40% by 2015 and 70% by 2050.[18] In recent years, Israel's annual use of water from the Sea of Galilee has shrunk from 513 million cubic meters (in 2001-2) to just 25 million cubic meters (2018–19) as desalinated water has taken its place."
- aglavine 7y agoCountries that export food can be seriouslsy affected.
- EugeneOZ 7y agoThis site should be added to the list of non-trustful sources. TASS is a propaganda agency. Two last "S" are for Soviet Union (Sovetskyi Soyuz in Russian) - this agency was made by communists as a propaganda tool and still plays this role. This news article, in particular, is a bs without proofs, without scientific magazines citations - they post such bs to create an impression of "positive news".
- WaylonKenning 7y agoIf requiring scientific magazine citations (which itself seems like a low bar), is our standard for if submissions are accepted, then there ain't going to be much news on Hacker News since most articles here don't meet that threshold.
- EugeneOZ 7y agoThis article is about scientific research.
- 5351254578 7y agoFrom what I can tell, its a cavitating bubble in a very fast flowing tube. Then water vapor is extracted from inside the bubble (not sure how). Given the energy required to keep the flow going, and the drip of clean water that would result it should be easily calculable what the energy input/volume of water is.
- jimrandomh 7y agoHeadline is a lie; it's 90% cheaper only compared to a process that isn't actually used. Flagged.
- ChristianBundy 7y agoCould you add some more info on which process isn't actually used, or links to resources that discuss it? I'm not familiar with the state of the art of desalination.
- nullc 7y agoThe article is comparing to using atmospheric pressure distillation, which isn't used for commercial scale desalination... reverse osmosis is primarily. (Where waste heat is available for 'free' flash distillation , which is already a lot more efficient than atmospheric pressure distillation, can be attractive... but if heat isn't available for free, RO uses about 80% less energy than multi-stage flash) So it sound to me like it may well be in an apples to apples comparison the method discussed in the article may be similar to or less energy efficient than RO. But maybe it could be used to enhance the usefulness of flash distillation for lower levels of waste heat.
- asdf21 7y ago>Compared with the methods listed above, our technology allows to reduce the cost of obtaining one cubic meter of fresh water tenfold,” the scientist pointed out. Who knows what that quote is even referring to... I wouldn't assume that the scientist was able to see the print layout of the article he would be quoted in.
- benevol 7y agoHere's the ultimate desalination technology that scientists will end up implementing: 1. Use nano-technology "bots" to attach magnetic particles to the salt in the water. 2. Activate strong magnets to extract the salt. Among the two byproducts will be the water that will have healing properties. The day this will hit the news, remember: You read it here first.
- jonwachob91 7y agoWhy would they use nano-bots instead of just ligands ?
- maerF0x0 7y agoI dont understand why desalination is an interesting problem given that it can be done whilst wasting minimal heat for processes that already need heat (or cooling due to too much heat). Things like smelting, power plants, nuclear, data centers...
- joshwa 7y agoThere's a good review of existing and novel desalinization technologies, including OP's supercavitation method, here: https://www.researchgate.net/publication/271673255_Large-scale_water_desalination_methods_A_review_and_new_perspectives https://www.researchgate.net/publication/271673255_Large-sca...