[HN Gopher] Desalination Breakthrough Could Lead to Cheaper Wate... ___________________________________________________________________ Desalination Breakthrough Could Lead to Cheaper Water Filtration Author : based2 Score : 166 points Date : 2021-01-01 15:47 UTC (7 hours ago) (HTM) web link (news.utexas.edu) (TXT) w3m dump (news.utexas.edu) | legulere wrote: | > Greg Foss of the Texas Advanced Computing Center helped | visualize these simulations | | Where are those visualizations? | dirtyid wrote: | Feels like cheap desalination breakthrough every year. I know | some middle east petro-states are building out the | infrastructure, but it doesn't seem like there's broad adoption. | Is it because cheap is still not cheap enough? Granted I don't | follow developments closely. I just want better non | flush/composting toilets. | golemiprague wrote: | There is broad adoption in places where you don't have other | alternatives. It is unlikely that manufacturing water will be | cheaper than just collecting it if there is enough sweet water | in the area. The thing is, many places in the world just don't | have the water so they use desalination whether it is cheap or | not. | pjc50 wrote: | There's a physical minimum energy required, but I don't know | close things are to this limit. | Gibbon1 wrote: | Found this. | | http://www.desware.net/Energy-Requirements-Desalination- | Proc... | | Seems like reverse osmosis takes 3.5-5.5 kwh/m3. Vs 0.86 | theoretical. So 15 to 25% of theoretical efficiency. | manfredo wrote: | Human civilizations have built population centers close to | sources for fresh water for millennia. Cities like Los Angeles | that require moving vast amounts of fresh water long distances | to be viable are a recent phenomenon - appearing only in the | last century or so. So a big reason for the lack of | desalination is a lack of demand. Yes, some places are | experiencing a lack of water but those are the exception to the | norm. | | And even if a population center does need more fresh water, | desalination is competing against traditional options: digging | wells, building aqueducts, and expanding reservoirs. And have | lots of experience - again, literally millennia of experience - | implementing these pieces of infrastructure. | | So in summary, desalination isn't seeing widespread adoption | because it's not necessary for most places and we have much | more experience with the alternatives. That said, it's great | we're still improving desalination and it puts the world in a | better place if water scarcity gets to the point that | traditional water infrastructure is not sufficient. | dylan604 wrote: | Give global warming more time and see where the need for de- | salination is at then. The droughts in SoCal are going to | keep making these traditional fresh water sources you mention | even more scarce. Less rain means lower lake water levels. | Less snow in the winters means less snow pack in the | mountains, so less water in the rivers and lakes below. All | of this occurring while SoCal has an essentially endless | supply of saltwater. | | Texas is in a similar situation. The lack of natural lake | resevoirs means their manmade lakes are also dependent on | rainfall that is very prone to drought conditions as well. | Texas also has easy access to saltwater. It's places like Las | Vegas, Phoenix, etc that will have a hard time getting | saltwater. | | The poplulation of all of these areas are only increasing | putting that much more strain on these limited fresh water | supplies. | jcranmer wrote: | > Cities like Los Angeles that require moving vast amounts of | fresh water long distances to be viable are a recent | phenomenon - appearing only in the last century or so. | | That's not exactly true. The Hohokam started building canals | in the Sonoran Desert maybe 1500 years ago (some of which | form the basis for the modern water supply system of | Phoenix!). Somewhat earlier than the Hohokam, the Romans were | infamous for their aqueducts, the longest of which stretched | over 250 miles. That's longer than the aqueducts that supply | New York City or even Los Angeles! | manfredo wrote: | The California aqueduct system has a total length of 444 | miles and the main branch is 300 miles [1]. More important | is the demographic impact of water management: Rome's | largest population center was ~1 million people, the | Hohokam ~80,000 as compared to the Los Angeles metro's 18 | million. Preindustrial populations had very little capacity | to built large infrastructure projects like these. Huge | population centers consuming substantially more water than | is brought to them naturally is a very recent phenomenon, | Roman aqueducts and Hohokam irrigation notwithstanding. In | most years Los Angeles imports 80-90% of its water. | Situations like these are not possible without | industrialized water infrastructure. Los Angeles used to be | primarily supplied by the Los Angeles river and its | population was correspondingly lower. | | Human need water daily to survive, and without pumped | plumbing building a population center that isn't near a | lake, river, or with access to groundwater is effectively | impossible. The Hohokam were no exception. Their aqueduct | system did not exist to deliver water to the city center, | but to their agricultural settlements. Their main | population center was along the Gila river. Preindustrial | irrigation systems are impressive when considering they | were built without machines, and moreso in hostile terrain | like the Sonoran desert or Afghanistan [2] - but it pales | in comparison to the demographic impact of water management | systems built over the last century. | | 1. https://en.wikipedia.org/wiki/California_Aqueduct | | 2. https://en.wikipedia.org/wiki/Qanat | Gibbon1 wrote: | Interesting thing about LA. I saw a table that showed how | much energy was required to deliver water from each source. | Some their sources of water require almost as much energy as | desalination. Something like 30-50%. | | I've wondered about using solar for desalination. Big issue | though is desalination plants are capital intensive. So you | really want to run them 24/7. | manfredo wrote: | Desalination can be done effectively with thermal | cogeneration. It's still inefficient, but since it is using | waste heat it's "free" energy so to speak. Saudi Arabia has | built such plants. The Soviet Union also built a fast | reactor that was cooled with salt water, which was | condensed and used as a freshwater supply [1]. | | Since ~80% of the world population lives on the coast, | using seawater as coolant and capturing the condensate | could represent a substantial source of freshwater. | | 1. https://en.wikipedia.org/wiki/BN-350_reactor | Melting_Harps wrote: | > So a big reason for the lack of desalination is a lack of | demand. Yes, some places are experiencing a lack of water but | those are the exception to the norm. | | With yet another year of drought in SoCal and heavy fires as | a result of dryer weather in Norcal seem to suggest | otherwise: I don't think it's a lack of demand at all. | | Carlsbad actually built their desalination (Poseidon) plant | when I still lived in CA permanently and the cost was the | biggest hurdle, as was waste management, as they sold the | water to neighboring areas at a premium in order to recover | the costs in a public-private undertaking. Carlsbad is one of | the more affluent cities in San Diego County so they had the | money during the bubble economy boom before the crash. | | Another one is/has been scheduled to be rolled out in | Huntington Beach apparently [0]. | | I definitely think desalination should be explored, tested, | and refined especially as the CO river source is/has been | closed and CA needs to take advantage of the massive resource | it has in addition to reducing consumption while figuring out | the waste issue with desalination. And nothing could | accelerate it faster than CA's massive need for fresh water. | A Day Zero situation is something that should be avoided at | all costs and in incredibly myopic in what is essentially the | 5th largest economy in the World. | | Personally speaking, I always figured it would be perto- | states trying to diversify that would be the biggest | financial backers of these facilities, as well as massive | solar farms, as the automotive World moved further way from | fossil fuel and OPEC goes to ever greater money losing | schemes to prop up the price of oil. Especially in a World | with evermore cheap and hot fiat being thrown at stupid | things like Airbnb and Doordash IPOs. | | 0: https://angeles.sierraclub.org/news/blog/2020/07/stop_the_ | po... | oxfordmale wrote: | I had an uncle who worked in the Middle East. One of the major | problems with desalination plants is corrosion of all the pipe | work, due to the high salt content. Better membranes will make | a difference, but will not solve the corrosion issue that | reduces the life time of a desalination plant. | CyberDildonics wrote: | What about cross linked polyethylene (PEX) ? Why use metal | pipes at all? | achow wrote: | Aren't plastics or polymer inert to salt water? | InvaderFizz wrote: | Yes, but I would guess that at the volumes these pipes will | be pushing, the abrasive qualities of a high salt | concentrate makes such soft piping material susceptible to | being eaten through rather quickly. | ianai wrote: | So use lower volume across more pipes in parallel? Seems | like something to engineer around. | sudosysgen wrote: | Seems like something where ceramic-like coatings would | help. | chrisco255 wrote: | Israel has led the way here: | https://www.scientificamerican.com/article/israel-proves-the... | | They've had efficient desalination tech for several years now | deployed in the country. My understanding is they use lava | stone to make the membranes more efficient. 55 percent of their | fresh water now comes from desalinated salt water. | ghshephard wrote: | Desalination has been inexpensive for 10+ years - ~$0.45/1000 | liters (m^3) if you are willing to enter a long term (10+ year) | contract. Down in Cabo, Hotels build their _own_ desalination | plants. | | The reason why you don't see broad adoption is that the | competition is free, and often comes with gravity assist. The | challenge with desalination isn't so much the cost of the | product, but (A) its competition and (B) The ocean (almost) | always has to be pumped up to get to its destination, which can | be expensive (C) Pollution - you end up with a lot of | byproducts that you need to dilute out into the ocean (and you | still end up with pretty devastated areas of the ocean floor | where it goes out). | | Cutting the price of desalination only helps with (A) - Even if | desalination were completely free, you would still need to deal | with geographic/pumping issues and the pollution. | hanniabu wrote: | Will we ever see this technology any time soon or is this like | battery tech? | CyberDildonics wrote: | Lithium Iron Phosphate batteries are close to regular lion | batteries but don't use manganese or cobalt and are much more | durable. They have much higher discharge rates and can undergo | around 8x the cycles, making their cost over time significantly | better than regular lithium ion. | | Lithium Titanate batteries have even more durability. | | Both of these are fairly recent to being available | commercially. | driverdan wrote: | LiFePO4 batteries have been available for 5+ years. They | aren't used in portable devices because they have lower | energy density than other lithium batteries. They're great | for fixed installations where density isn't an issue. | CyberDildonics wrote: | I think density per volume is similar, but density per | weight is a little less from them being heavier. They | should work fine in plenty of portable situations, not | everything is a drone. Power tools, universal battery packs | that offer AC, USB, etc., scooters, motorcycles, and all | sorts of other stuff should work very well. Even golf carts | and some scooters use lead acid batteries. | Gibbon1 wrote: | It's like battery tech in that there are a lot of false starts | and dead ends. And commercialization tends to play out over 1-2 | decades. | | That said I think the title using the word break through is | clickybait. More honest title would be marginal improvement | might lead to low capital costs for desalinated water plants. | maxerickson wrote: | Lithium ion batteries went through an incredible revolution the | last 10 years, prices dropped by a factor of ~10. | | https://twitter.com/ProfRayWills/status/1342632562477264896 | eloff wrote: | That's ironically why we don't see new battery tech | materialize. It has to come out of the gate more cost | efficient than Li Ion, which is a tall order now with all the | efficiencies of scale the latter enjoys. I believe the term | technological lock in is used to describe this problem. | bluGill wrote: | Chemically it is hard to believe that we can do better than | lithium anyway. | choeger wrote: | That's not entirely true. The technique to mass-produce Li | ion cells (basically: create massive sandwiches and roll | them) can probably be applied to most other chemistries. | eloff wrote: | I think that's mostly only superficially similar, but I'm | not an expert in the field. | simonh wrote: | I still clearly remember the Nickel-Cadmium days. Kids don't | know they're born. ;) | VBprogrammer wrote: | I'm sure there are answers in the actual paper behind this press | release but I wonder how much more it costs to make the membrane | so much more uniform. | cinntaile wrote: | Papers don't usually talk about cost, so I wouldn't count on | it. | MichaelZuo wrote: | "Desalination Breakthrough Could Lead to Cheaper Water | Filtration if we don't consider costs" sounds like a more | honest title | twic wrote: | This is the actual paper, which is not open access: | | https://science.sciencemag.org/content/371/6524/72 | dstick wrote: | I always wondered, so now's the time to ask I guess, why aren't | these publicly accessible? Aren't they paid for with government | (i.e. public) money? | jcranmer wrote: | Not necessarily. I don't have access to the actual article | itself, so I can't read the section of the article that | indicates who funded the work. But several authors do list | corporate affiliation (DuPont and Dow), not that that is | itself proof of non-public funding. | Finnucane wrote: | Some legislation has been proposed in the US Congress to | require access to research paid for with tax money (seems | pretty reasonable), but so far I don't think it's been able | to get past Dr. No. | the_svd_doctor wrote: | Even when you get a government grant for research, sometimes | there are open-access requirements for publications, but | sometimes not. It varies. | | Paper directly written by government employees (like national | labs) are usually accessible for free (like on | https://www.osti.gov/). | ortusdux wrote: | Would it be possible to DPR these publications? I would | assume that the funding agency retains a copy of the paper | once published. | swebs wrote: | >Paper directly written by government employees (like | national labs) are usually accessible for free | | I'm pretty sure all of them are required to be in public | domain | driverdan wrote: | Read the article. It says it was funded by DuPont. | dstick wrote: | That doesn't answer my question without prior knowledge. | Luckily others did manage to provide an insightful answer. | | > why aren't these publicly accessible? | | And you say: it's sponsored by Dupont. So let me rephrase | the question incorporating the new bit of information you | provided: | | Why would a paper be hidden behind a paywall if it's | sponsored by a commercial company? | | It would make sense if it was completely off limits. But | paying a few hundred dollars (?) means it is still semi | public. It's no secret, but it's not public either. Why? | tetris11 wrote: | To prop up the journal, both financially and from an | exclusivity angle. If the editors of the journal happen | to be friends of DuPont, and the research is of actually | that impactful, than a barrier to access might be | beneificial | jeroenhd wrote: | It's only partially supported by public money, as far as I | can tell. Perhaps the industrial sponsors don't want it to be | open access? | | Luckily, the paper is accessible through SciHub it seems. | | From the paper: | | Funding: Financial support from The Dow Chemical Company and | DuPont is acknowledged. T.E.C. and E.D.G. acknowledge | financial support from the National Science Foundation under | awards DMR-1609417 and DMR-1905550. K.P.B., A.L.Z., and | E.D.G. also acknowledge support from the Center for Membrane | Science, Engineering, and Technology (MAST) and the National | Science Foundation under award IIP-1841474. M.K. acknowledges | support from the National Science Foundation under award | CBET-1946392. B.G. and B.K. are funded in part by the | National Science Foundation under award CMMI-1906194. B.G. | and B.K. also acknowledge computing support from XSEDE TG- | CTS110007 | Faaak wrote: | And for those wondering, you should not go to sci-hub to get | the paper, because that would be illegal ;-). | rconti wrote: | > The seeds were planted when DuPont researchers found that | thicker membranes were actually proving to be more permeable. | This came as a surprise because the conventional knowledge was | that thickness reduces how much water could flow through the | membranes. | | It's amazing how often "how it works" is taken for granted. This | reminds me of the trend of racing bicycle tires. It used to be | "obvious" that you wanted to run a skinny narrow tire at high | pressure, for better aerodynamic and rolling efficiency. Even | when they started wind tunnel (for tires and wheels) and rolling | resistance testing, it was done on steel rollers, not on actual | road surfaces. It was assumed that rough roads caused efficiency | losses primarily in tire flex (heat), so it made sense to keep | pressures high. | | In the past decade or so, there's been a radical shift towards | wider tires and wheels. There are a lot of people riding/racing | on 28-32mm wide tires where you would have been laughed at a | decade ago, and told to go back to the "efficient" 23mm wide | tires. 10-15 years ago, you'd want to be running 120psi on a 23mm | wide tire and today you want to run your tire pressure as LOW as | possible, and run a wider tire to compensate, to give more air | volume to spread the load and bumps across. The rolling | resistance is LOWER, because they've found that the energy losses | from rough roads or from bumps is in the tremendous amount of | energy expended to move the 150-200lbs of "unsuspended" rider and | bicycle up and down rapidly. You're losing single-digit watts in | rolling resistance on that lower pressure tire, but saving tens | or hundreds of watts in energy that would be lost moving the | rider's mass up and down. | | I'm not kidding about the "laughed at" part, either. I'm looking | up how wide a tire I can fit on my 12 year old road bike, and | there are plenty of downright ABUSIVE forum posts from just 6 or | 8 years ago, telling people to go buy a mountain bike if they | want to run wider than 25mm tires on my particular bicycle, where | I'm trying to fit a 28 and would really like to run a 32 if | possible. | | And a lot of these findings started off as "huh, that's weird" | when testing newer wheel shapes in the real world. | | https://cyclingtips.com/2016/08/cyclingtips-podcast-episode-... | baxtr wrote: | _> there are plenty of downright ABUSIVE forum posts from just | 6 or 8 years ago_ | | Reminds me of another post from today: | | https://news.ycombinator.com/item?id=25600274 | xorcist wrote: | Sounds like the optimum size was a little bit off what was | previously thought, but not by much. | | 28mm is still a _very_ narrow tire, by any other standard than | racing bikes. It 's narrower than any utility bike and about | half than you would run on a mountain bike, and describing the | difference as radical seems a bit excessive to an outsider. | Those tire pressures also probably excludes anything close to a | flat tire. | | It's not like anyone thought harder tires were always better. | Otherwise they would all be running metal or wooden tires. | After all, that was what everyone did before rubber tires were | invented, which they were because they were more efficient than | bumping around on wood. If someone had guesstimated the optimum | at 23mm and 120psi and it was measured at 28mm, was it really | that bad? | kevin_thibedeau wrote: | We're now seeing hookless carbon rims that top out at 75psi. | The industry has unfortunately taken this trend by the reins | and will be shoving substandard wheels down everyone's throat | in the name of profit. | fumar wrote: | Substandard in what way? | kevin_thibedeau wrote: | They will fail where a stronger rim won't | tripsus wrote: | Thank you for sharing this. | cjbenedikt wrote: | There will still be a brine problem | though...https://unu.edu/media-relations/releases/un-warns-of- | rising-.... ___________________________________________________________________ (page generated 2021-01-01 23:00 UTC)