# Graphene does water desalination **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [April 3, 2017, 9:33pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682 "2017-04-03T21:33:58Z")\ **Posts on this page:** 19\ **Page:** 2
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [April 4, 2017, 3:45pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/21 "2017-04-04T15:45:24Z")
> [@TriPolar](#): > > I suppose graphene might make a stronger, longer lasting membrane for desalination. At $3,600 per sq. in. for graphene it has to be worth it, right? :rolleyes: If I’m in a lifeboat in the middle of the South Pacific, hell yes. ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [April 4, 2017, 3:47pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/22 "2017-04-04T15:47:16Z")
> [@TriPolar](#): > > Graphene is to material science as Windex is to Greeks. It can do anything. > > I suppose graphene might make a stronger, longer lasting membrane for desalination. At $3,600 per sq. in. for graphene it has to be worth it, right? :rolleyes: Well, aluminum used to be one of the most expensive metals you could get…that’s one of the reasons, IIRC, that the Washington Monument had an aluminum cap stone on top. That sort of changed, however, once they figured out how to make the stuff in quantity and cheaply. Today, graphene isn’t something that is easy to mass produce, so that’s why it costs so much. Assuming they can ever figure out how to produce it cheaply and in quantity, however, it would change that equation. Wouldn’t you say? ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [April 4, 2017, 3:55pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/23 "2017-04-04T15:55:42Z")
> [@jtur88](#): > > It would threaten to turn comfortable economics upside down for a lot of powerful vested interests, so expect plenty of roadblocks. Sadly, that happened in Greece with a Trial Project of the EU: they built a small Swimming platform with solar cells and wind wheel to provide electricity to desalinate sea water. They wanted to test it for some of the small Greek Islands that have almost no drinking water of their own. They currently rely on water being desalinated - with lots of electricity, produced by burning coal - on the mainland and then shipped out. This is expensive. Also, when there are storms in spring and autumn, the ships may be delayed for 3-5 days, which is difficult for the islanders and makes the water smell bad. So the islanders were really for it. The EU wanted to run the Project 20 years to iron out all Problems that might arise, and then mass produce for many Areas. During the first years, it turned out that the excess salt being secreted attraced clams and algae, on which fish fed, so that the People who regularly drove the boat over to check on the apparatus could also catch their dinner. But a few years later, turned out the machine had been damaged, because the People owning the desalination plants on the mainland and the ships transporting the water didn’t want to lose the income. ☹ ---
**Author:** ![Slash1972](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/slash1972/32/6461_2.png) [@Slash1972](https://boards.straightdope.com/u/Slash1972)\ **Post date:** [April 4, 2017, 4:16pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/24 "2017-04-04T16:16:32Z")
Wait, so there was a successful project, and because the machine got damaged they just up and ended the project? ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [April 4, 2017, 5:10pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/25 "2017-04-04T17:10:52Z")
> [@XT](#): > > Well, aluminum used to be one of the most expensive metals you could get…that’s one of the reasons, IIRC, that the Washington Monument had an aluminum cap stone on top. That sort of changed, however, once they figured out how to make the stuff in quantity and cheaply. Today, graphene isn’t something that is easy to mass produce, so that’s why it costs so much. Assuming they can ever figure out how to produce it cheaply and in quantity, however, it would change that equation. Wouldn’t you say? Graphene is already under $100/g. Membrane raw material cost is not a significant contributor to RO CapEx, so this stuff could be free without much impact. ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [April 4, 2017, 5:51pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/26 "2017-04-04T17:51:38Z")
This is somewhat old; there have been a number of articles over the last few years about advances in graphene oxide membranes. The reason it is potentially important is that the energy needs are less compared to typical polymer membranes. [This article](https://www.greenprophet.com/2014/12/graphene-nanotechnology-makes-desalination-100-times-more-efficient/) says only 1/100th the energy is needed, but I view that claim with healthy skepticism. [This one from MIT](http://news.mit.edu/2015/desalination-gets-graphene-boost-jeffrey-grossman-1102) seems more science, less journalism, and gives numbers of “15 percent less energy for seawater and up to 50 percent less energy for brackish water,” which is still an important improvement even if it won’t change the world. ---
**Author:** ![constanze](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@constanze](https://boards.straightdope.com/u/constanze)\ **Post date:** [April 4, 2017, 6:59pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/27 "2017-04-04T18:59:23Z")
> [@Slash1972](#): > > Wait, so there was a successful project, and because the machine got damaged they just up and ended the project? It was a test Project to run for 20 years, and it was sabotaged after running for only a couple of years. It was under the care of the Greece govt., which has a bad record of getting Money from the EU for Projects to help its infrastructure, building a shiny lab and then disappearing the rest of the Money and neglecting the Project. So if the Greece govt doesn’t care to continue the Project, the EU doesn’t force them. This is one of the Problems: it’s true that the “cut all govt. expenses” program was stupid and hurt both the People of Greece and the economy badly, because cutting hurts the economy. But it’s also true that most politicans, regardless of Party, are corrupt, and the other parts of the Troika plan, like raising taxes from the rich, failed because of that. So the Greek People blaming their suffering on the Troika by comparing Merkel to Hitler is only half true, because the plan was a three-prong, but their own politicans hindered the two parts that would have hurt them, so the plan as a whole couldn’t work. (One example of the corruption: the EU gave to the Greek govt. a list of capital invested in tax havens violating laws, so they could go after that. By the time the list reached the Minister of finance, half of the names on the list had somehow disappeared - because they were personal friends of the politicans? Another example: when they set about taxing rich People, it turned out there was no Register of who owned land and houses, so no way to evaluate who was rich. And the govt. somehow didn’t bother to create such a registry to go Forward). ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [April 4, 2017, 7:08pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/28 "2017-04-04T19:08:04Z")
How much pressure is required for the existing desalination membranes? How deep do you have to go to reach that pressure? Why not put the membrane at that depth and pump the desalinated water to the surface? Would the pumping from that depth use as much power as is now used to push the water through the membrane? ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [April 4, 2017, 7:29pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/29 "2017-04-04T19:29:00Z")
> [@usedtobe](#): > > Would the pumping from that depth use as much power as is now used to push the water through the membrane? I would think so after observing pumps in aquariums. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [April 4, 2017, 7:34pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/30 "2017-04-04T19:34:03Z")
> [@XT](#): > > Well, aluminum used to be one of the most expensive metals you could get…that’s one of the reasons, IIRC, that the Washington Monument had an aluminum cap stone on top. That sort of changed, however, once they figured out how to make the stuff in quantity and cheaply. Today, graphene isn’t something that is easy to mass produce, so that’s why it costs so much. Assuming they can ever figure out how to produce it cheaply and in quantity, however, it would change that equation. Wouldn’t you say? > [@Ruken](#): > > Graphene is already under $100/g. Membrane raw material cost is not a significant contributor to RO CapEx, so this stuff could be free without much impact. It’s certainly new stuff. Lots of things including graphene’s cousin carbon-fiber were once very expensive and have become much more practical over time. But there is the question of whether we need a new membrane for desalination. I don’t know anything about the subject, but there are and have been such membranes for a long time and graphene will need to show some competitive edge. Perhaps it is more durable, or safer, or a better filter, but it will take time to tell. And $100/g for graphene? 1 gram of the stuff is a lot, that’s pretty damn cheap already. Better get started on that space elevator. My plan is to put a small conventional elevator on top of a 100 mile tall mountain of graphene. Much more practical now that it will cost less than a 100 mile tall mountain of money. ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [April 4, 2017, 7:47pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/31 "2017-04-04T19:47:56Z")
> [@Hari\_Seldon](#): > > I didn’t read the article. There is no point since they haven’t figured out how to reverse entropy. If they have, it would be far greater news than desalination of sea water. I didn’t read it either, since they haven’t perfected macro-level teleportation or faster than light travel. Why the bizarre response? The article wasn’t _about_ reversing entropy, it was about desalinizing sea water. ---
**Author:** ![Oukile](https://avatars.discourse-cdn.com/v4/letter/o/13edae/32.png) [@Oukile](https://boards.straightdope.com/u/Oukile)\ **Post date:** [April 4, 2017, 8:27pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/32 "2017-04-04T20:27:19Z")
> [@carnivorousplant](#): > > Will it work in a lifeboat? > [@Mavic\_Chen](#): > > I was thinking the same thing, or maybe a patch sewn into a life jacket so you would be ok for water while lost at sea. > [@carnivorousplant](#): > > I wonder how much pressure is required. [There are already devices that do that.](https://www.google.com/search?q=desalinator+hand+pump&ie=utf-8&oe=utf-8) They work with hand-operated pumps. From what I read (a while ago), it takes a few minutes of pumping to get a glass of drinking water. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [April 4, 2017, 11:54pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/33 "2017-04-04T23:54:46Z")
> [@Oukile](#): > > [There are already devices that do that.](https://www.google.com/search?q=desalinator+hand+pump&ie=utf-8&oe=utf-8) They work with hand-operated pumps. From what I read (a while ago), it takes a few minutes of pumping to get a glass of drinking water. Cool. Thanks, Oukile. I’ll buy one before any cruise Mrs. Plant (v.3.0) wants to take. ---
**Author:** ![Mavic\_Chen](https://avatars.discourse-cdn.com/v4/letter/m/e56c9b/32.png) [@Mavic\_Chen](https://boards.straightdope.com/u/Mavic_Chen)\ **Post date:** [April 5, 2017, 8:35am UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/34 "2017-04-05T08:35:55Z")
> [@Oukile](#): > > [There are already devices that do that.](https://www.google.com/search?q=desalinator+hand+pump&ie=utf-8&oe=utf-8) They work with hand-operated pumps. From what I read (a while ago), it takes a few minutes of pumping to get a glass of drinking water. Here’s a quote from an Amazon review I just found of a hand operated de-salinator: “This device, while approved by the Navy and Coast Guard for sea water desalination aboard life rafts, is NOT what you want for continued coastal survival. This is designed for life-raft-one-time-use. PERIOD. Each time it is used, you have to prep and clean the membrane from all biologicals that may be on it, you have to keep the membrane serviced thereafter. Once a year, it has to be factory inspected and serviced. Letting the membrane dry out will ruin the unit. This is HIGH MAINTENANCE for a simple manual-pump reverse osmosis hydraulic pump with a salt membrane in it. If you aren’t on a life raft, then you DON’T need this unit. What you most-likely would benefit far more from is a traditional RO filter system, maybe even a home system with a salt filter added and an AC/DC inverter to power it.” Sounds like a lot of bother, was just wondering how this stacks up against the proposed graphene solution in terms of maintenance in a life raft situation. If it were to be easily cleanable (maybe with the clean water it produces?) and had a prolonged shelf life it might be way better. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [April 5, 2017, 8:49am UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/35 "2017-04-05T08:49:26Z")
> [@Qadgop\_the\_Mercotan](#): > > Too much use of the word ‘could’ for my taste. > > In other words, I’ll wait for more data. > > But I’ll wait hopefully. Yep, an almost comically weasily article. “Once they’ve got the costs down, we’ll see if it’s more efficient than existing methods. And if it helps in any way with the main issue of membranes (keeping them clean). But if it’s better than existing methods, _it’ll be better than existing methods!_” ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [April 5, 2017, 11:07am UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/36 "2017-04-05T11:07:05Z")
> [@usedtobe](#): > > How much pressure is required for the existing desalination membranes? > > How deep do you have to go to reach that pressure? > > Why not put the membrane at that depth and pump the desalinated water to the surface? > Would the pumping from that depth use as much power as is now used to push the water through the membrane? I’m confused. There has to be a pressure differential across the membrane for it to work, since the pressure is meant to push the water through the membrane, right? Just putting a membrane in deep water would mean the pressure would be the same on both sides, so nothing would happen, right? Or have I missed something? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [April 5, 2017, 11:28am UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/37 "2017-04-05T11:28:27Z")
> [@chorpler](#): > > I’m confused. There has to be a pressure differential across the membrane for it to work, since the pressure is meant to push the water through the membrane, right? Just putting a membrane in deep water would mean the pressure would be the same on both sides, so nothing would happen, right? Or have I missed something? The water is normally pumped to the desalination plant from the ocean which is at a higher elevation than sea level. So gravity provides the pressure. Not really a problem with the system since the desalinated water isn’t useful to anybody unless it’s pumped out of the ocean anyway. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [April 5, 2017, 12:41pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/38 "2017-04-05T12:41:04Z")
> [@chorpler](#): > > I’m confused. There has to be a pressure differential across the membrane for it to work, since the pressure is meant to push the water through the membrane, right? Just putting a membrane in deep water would mean the pressure would be the same on both sides, so nothing would happen, right? Or have I missed something? In reverse osmosis filters in the aquarium hobby, the pressure differential is caused by the home water pressure. Some people use electrical pumps to increase the pressure. ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [April 7, 2017, 5:12pm UTC](https://boards.straightdope.com/t/graphene-does-water-desalination/783682/39 "2017-04-07T17:12:56Z")
> [@Dewey\_Finn](#): > > I’ve asked my computer for an answer to that question. I’ll get back to you when it comes up with something. Let me save you some time: 42. [Previous page](https://boards.straightdope.com/t/graphene-does-water-desalination/783682.md?page=1)