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Chemists Work to Desalt the Ocean for Drinking Water, One Nanoliter at a Time
- hernan604 13y agodoes the ocean still clean these days ? very nice job, expect to see it available soon
- voltagex_ 13y agoI suspect you got downvoted because English isn't your first language. Something like: "Is the water from the ocean clean enough to drink? Hope to see this product available to buy soon" might be better
- cmsmith 13y agoThis is a great question. Distillation has the side effect of removing all of the microbes from water and sanitizing the output, but if this method only removes the salt will the output water be clean enough to drink?
- ars 13y agoDo you think they clean your local city water? They don't. They filter it a bit, then add chlorine to deal with biologicals, and that's it.
- tsotha 13y agoBut municipal water typically comes from rain or snowfall. The distillation has already been done.
- ars 13y agoYou wish. No, it usually comes from a river. And guess where the waste water from a sewage treatment plant goes? Right back into the same river, only downstream. And that's where the next city down the line picks it up. That water gets recycled multiple times on the way to the ocean, by each city on the river. That's not a bad thing! But the water can hardly be called distilled.
- tsotha 13y agoWhere I live the river water comes from snow packs. And nobody's allowed to discharge treated sewage into rivers. Gross.
- monochromatic 13y agoI'd love to see an energy-conservation analysis of this technique. How many joules per liter does it actually require?
- solox3 13y ago40 nL of desalted water per minute, for a minute, using 3.0V voltage (from article) and 0.7 A current (standard AA, "store-bought battery" from article), yields 3.2 GJ/L. Even if we give it the benefit of the doubt and say we're overestimating the current by a factor of 100, 32 MJ/L still a ridiculous amount of energy, and ~10x more than just distilling water through evaporation, which is 2.23 MJ/L.
- sbierwagen 13y agoThe actual paper ( http://libgen.org/scimag5/10.1002/anie.201302577.pdf http://libgen.org/scimag5/10.1002/anie.201302577.pdf ) says they manage an efficiency of 25 mWhL^-1 (90 joules per litre) Where did you get that 0.7A number?
- solox3 13y ago0.7A is the current of the "store bought" (AA) battery, suggested by the article. To make this technology energetically favourable to boiling, it must not exceed ~700μA in current, and it has to be far less than that to be worth its complexity.
- sbierwagen 13y agoUh? No battery[1] delivers a constant amount of current: http://en.wikipedia.org/wiki/Ohm%27s_law http://en.wikipedia.org/wiki/Ohm%27s_law Solving for current, Ohm's law is I = V/R. You only deliver .7 amps of current into a 4.285 ohm load. If you connect a 3 volt battery to a 1,000 ohm resistor, then only 0.003 amps of current will flow, which is 9 milliwatts. Connect a 3 volt battery to a .01 ohm load (a dead short, almost) and 300 amps of current will flow, (900 watts!) very briefly, until the battery voltage sags under load. 1: Or any voltage source in general, barring some trickery that you can't do with a simple electrochemical battery.
- bcks 13y agoThe page is returning a database error for me, but the Google cache shows a blog entry describing and linking to the low-power desalination technique announced here: http://www.utexas.edu/news/2013/06/27/chemists-work-to-desalt-the-ocean-for-drinking-water-one-nanoliter-at-a-time/ http://www.utexas.edu/news/2013/06/27/chemists-work-to-desal...
- andymcsherry 13y agoYeah, I'd recommend that link. It's slight more technical and written in a neutral voice. The original link feels like more of an excuse for a rant against the IMF.
- ParahSailin 13y agohttp://libgen.org/scimag5/10.1002/anie.201302577.pdf http://libgen.org/scimag5/10.1002/anie.201302577.pdf
- zw123456 13y agoIt would be great if a Solar cell or small panel could power it. That could be a life saver in emergency situations.
- stephengillie 13y agoA solar panel can run this. Or, to be more specific, a small (3" x 3") solar panel could charge a 3v battery which could power this device. I have solar-powered holiday lights which operate on 3v, this application would be simply replacing the lights with this chip. I've actually replaced the charging circuit with a TI MSP-430[1], and powered it directly with solar power. [1]a microcontroller similar to Arduino which operates on 3.3v and was intended to cost $4.30 for the entire development kit. http://www.ti.com/msp430 http://www.ti.com/msp430
- dangrossman 13y agoThis thing is producing nanoliters per minute with that power. Sure, you can power this device with a small panel, but you'll die of thirst before it makes enough water to fill one glass.
- stephengillie 13y agoHopefully they optimize the device for v0.2 ;)
- ars 13y agoThe absolute minimum energy you need is 2.2kJ per liter. A 4x4 inch solar cell could do that in about 2 hours. However I suspect that you'll never actually desalinate water for that amount of energy in a portable system. The very best commercial systems manage to do it with about 3 times the energy of the minimum. More common ones are about 10 times the minimum.
- sbierwagen 13y agoThe absolute minimum energy you need is 2.2kJ per liter. Where's that number from? For what process?
- fernly 13y agoThe paper linked from the article is behind a pay wall but the abstract[1] is very brief: "A simple power supply is used to apply a 3.0 V potential bias across a microelectrochemical cell comprising two microchannels spanned by a single bipolar electrode (BPE) to drive chloride oxidation and water electrolysis at the BPE poles. The resulting ion depletion zone and associated electric field gradient direct ions into a branching microchannel, consequently producing desalted water." [1] http://onlinelibrary.wiley.com/doi/10.1002/anie.201302577/abstract http://onlinelibrary.wiley.com/doi/10.1002/anie.201302577/ab...
- sbierwagen 13y agoIt's already being commercialized: http://www.okeanostech.com/ http://www.okeanostech.com/
- efsavage 13y agoI don't put much stock in those who make claims like "the next world war will be over water", because we have a massive supply of water (the ocean) and a massive supply of energy (the sun) to power whatever we need to do to make it drinkable. A floating desalination plant powered by an x000-acre floating solar platform, pumping clean water back to shore, and dispersing slightly saltier water across a wide area, doesn't seem like science fiction to me, and doesn't seem very destructive. The process doesn't even have to be super efficient, we may even end up using old-school techniques like distillation or electrolysis to keep the mechanisms simple. (granted this helps coastal regions more than inland ones, but moving population-heavy coastal areas to this system will preserve more of the natural water supplies for the inland needs).
- djloche 13y agoWater shortages are political in nature. The technical and logistical parts have been solved for a while.
- XorNot 13y agoStill doesn't sell massive war - shortages are political in regions where people generally have nothing. Wars - technological ones of the type major powers would fight - are expensive. Far more expensive then any amount of desalinization we would need to build.
- alan_cx 13y agoIt could easily mean massive war, if a war is politically required. One country holding out water supply to another country for whatever reason. Say such a country has a big friend, like say the US? Not to say it will happen, I believe and hope it wouldn't happen, but it could.
- sbierwagen 13y agoThe process doesn't even have to be super efficient Economics are important. We didn't go back to the moon because it was too expensive, and we're not going to see massive-scale desalination because it's also too expensive: http://physics.ucsd.edu/do-the-math/2012/10/the-energy-water-nexus/ http://physics.ucsd.edu/do-the-math/2012/10/the-energy-water... California uses 46 billion gallons of water per day. Supplying 25% of this via desalination would require 36 GW of thermal-equivalent power. California runs on 30 GW of electricity, and a total energy budget of 262 GW (thermal; from oil, gas, coal, hydro, nuclear, etc.—according to the EIA). That’s a substantial amount for 25% of our water needs. A "ten dollar glass of water" isn't even the big issue. Agriculture requires water, and expensive water means expensive food. Expensive food means people die, mostly from bullet wounds inflicted by people who are hungry. (I hardly need to provide citations for the number of wars resulting from food shortages)
- haldujai 13y agoOriginal paper: doi: 10.1002/anie.201302577 From their paper it is mentioned they have a 40 nanolitre/min flow rate (25% desalination rate, 99% is considered safe to drink water). They use an electric pole to generate an ion depletion zone, their problem right now lies in the severely limited flow rate and desalination rate. From my understanding the 25% desalination rate does not compound linearly and decreases in efficiency as the concentration of salt ions decreases. Additionally their flow rate is 0.4 microlitres per minute, this would equate to needing 625 000 channels for one pass only to get 250mL / min. Scaling for microfluidics isn't simply using a larger pipe size, microfluidic devices largely operate with minimal forces and a Reynolds number of 1, that doesn't hold as you get larger. The other big problem here is that this requires pressure driven flow, to do that they made two reservoirs of uneven height on opposite ends to drive flow. Again this is very electrically cheap (picowatts) when dealing with such small and perfect flow conditions. The biggest problems they need to address are the low filtration rate and the low flow rate, it does not seem like there is a simple answer to the first, they do state that they are conducting a larger scale experiment that they will publish later. I largely suspect that the larger scale experiment will fail in efficiency as another group (doi:10.1038/nnano.2010.34) who also uses a ion depletion zone (albeit by a different mechanism) found after publishing that they were orders of magnitude (10^3) too low in their predictions. If anything this will perhaps be better than small, portable RO setups but not replace large factories which are actually pretty efficient.
- rflrob 13y ago>Additionally their flow rate is 0.4 microlitres per minute, this would equate to needing 625 000 channels for one pass only to get 250mL / min. Scaling for microfluidics isn't simply using a larger pipe size, microfluidic devices largely operate with minimal forces and a Reynolds number of 1, that doesn't hold as you get larger. What about parallelization? Are there any obvious downsides to simply having lots of the active units, aside from the (what seems to me largely manageable) increase in micro fluidic chip complexity?
- sbierwagen 13y agoUsing 625 000 channels is parallelization. Those channels are in parallel.
- jyf1987 13y agoits not only make ocean water drinkable, but also make ocean be livable, especially those tropic oceans, they would build solar powered water tower and soilless vegetable/food factories, war might break out between some countries for the ocean
- Ellipsis753 13y ago"The new method requires so little energy that it can run on a store-bought battery." What a silly measurement. I can buy a laptop battery or a car battery at a store. Also it does not give any idea of how much water could be produced from the battery. A teaspoon per battery probably isn't too great. (Although at the moment they get only nanoliters of salty water from it of course).
- Luyt 13y agoA similar silly unit is used to measure 'green' energy: "This windmill can power 10.000 households". As if we're too stupid to understand a kWh figure.
- aroch 13y agoIt's nothing to do with being smart or stupid, 10K homes is a more descriptive number (more easily visualized) than kWh for describing energy production to the general populace.
- kunil 13y ago"consumes less energy and is dramatically simpler than conventional techniques." I remember a video that shows some kind of filter (it looked like a plastic sheet). They were simply pushing water against it and you get clean water from salty water. I don't think it gets easier than that. However if I remember correctly the filter gets unusable after a while
- ars 13y agoYou need energy to "push" the water through the membrane. A LOT of energy. It's called reverse osmosis if you want to look it up.
- pipboy3 13y agowater chip? I need to buy lot of them before World War III starts. I got a feeling I'm gona need one in the vault.
- usablebytes 13y agoWhy do we usually utilize science to fix the wrong problem? Shouldn't we be making more efforts on 1) Growing more trees 2) Reducing environmental pollution 3) Controlling human population ???
- backprojection 13y agoBecause the earth isn't designed to take care of us. If we had stayed a small pre-industrial society, we would still eventually die of something - there are myriad ways species go extinct. The only way to ensure long-term survival is to develop science and technology quickly enough to solve problems (both natural and artificial) as they come up. This includes solving problems created by past generations, who necessarily did not have access to the knowledge needed to avoid creating those problems in the first place. It's certainly not guaranteed that we will do so fast enough.
- ajuc 13y agoThere's more than 8 000 000 000 of us, if everybody were just doing the thing with the greatest priority it would be very ineffective division of work. Like digging one hole with 1000 people. As a humanity we can (and should) multitask, especially when it comes to science and inventions, because you never know which seemingly pointless path can lead you to a great breakthrough. Imagine everybody since antiquity worked only on the greatest humanity problems as they've seen it at the time. No useless stuff like music, so no irrational numbers for example :)
- BillyMaize 13y agoThe population of the world is slightly under 7 billion.
- CapitalistCartr 13y agoThe US Census bureau says 7.097 Billion. They estimate that the world population exceeded 7 billion on 12 March 2012. https://www.census.gov/popclock/ https://www.census.gov/popclock/ http://www.worldometers.info/world-population/ http://www.worldometers.info/world-population/
- brownbat 13y ago> "The new method requires so little energy that it can run on a store-bought battery." We currently have techniques that require no additional power (just using the sun), but almost every desal operation uses a powered method. Power consumption isn't the only factor here. A low power technique that has throughput per area equivalent to solar stills is just worse than all available alternatives. If you made a device that turns the briny sludge byproduct into fuel or some other consumable, that would be amazing.