[HN Gopher] Desalination Breakthrough Could Lead to Cheaper Wate...
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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-....
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