New Rechargeable Battery Uses Water

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New Rechargeable Battery Uses Water

Posted by samzenpus on Thursday May 5, 2011 @02:14AM from the I-want-my-water-engine dept.

fergus07 writes "Scientists at Stanford have developed a battery that uses nanotechnology to create electricity from the difference in salt content between fresh water and sea water. The researchers hope to use the technology to create power plants where fresh-water rivers flow into the ocean. The new 'mixing entropy' battery alternately immerses its electrodes in river water and sea water to produce the electrical power."

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ALready an energy shortage there. by Anonymous Coward · 2011-05-05 02:18 · Score: -1

Considering how many rivers aren't even making it to the sea any longer (like the Colorado), I don't see this as a long term or viable energy source. Fresh water has become too precious for energy.
1. Re:ALready an energy shortage there. by Anonymous Coward · 2011-05-05 02:24 · Score: 2, Insightful
  
  Wow, two fallacies in one!
  A sweeping generalization AND a stunning ignorance of the hydrologic cycle.
  Well done good sir, well done *slow clap*
2. Re:ALready an energy shortage there. by Ferzerp · 2011-05-05 02:25 · Score: 3, Informative
  
  Wait, you actually think water is disappearing, going poof? Where do you think this water is going? Water is not something you use up and then there is no more. You see, it evaporates, and then it rains down again clean. Now it may not be where you expected it would be, or it may end up unfit for use in areas with contaminants, but the water is still there.
  You realize there are nearly inexhaustible supplies under the ground right? If you suck it out faster than it seeps back down, guess what, the water still exists. We could potentially use it faster than we harvest it, but to assert that water is a scarce resource is very, very misleading. You can always expand your collection techniques.
  Or are you suggesting we are in danger of locking up *all* of the hydrogen and oxygen on the earth in to other compounds?
  Oh, you know that salt water? Let it evaporate, and magically you have more fresh water. :P
3. Re:ALready an energy shortage there. by Anonymous Coward · 2011-05-05 02:29 · Score: 0
  
  Actually there are more than two. I counted four.
4. Re:ALready an energy shortage there. by Skal+Tura · 2011-05-05 02:30 · Score: 1
  
  actually fresh water is a bit scarce in some places, such as UAE & there abouts. But yeah... Not exactly that scarce :)
  
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  Pulsed Media Seedboxes
5. Re:ALready an energy shortage there. by Anonymous Coward · 2011-05-05 02:39 · Score: 0
  
  There is such a demand for fresh water that many many rivers around the World aren't flowing into the sea -which this technology is dependent upon. And as the World's population increases, this problem will continue.
  It's also interesting to note that potable water is becoming increasingly scarce around the World.
  *Slow clap* indeed.
6. Re:ALready an energy shortage there. by tnk1 · 2011-05-05 02:58 · Score: 1
  
  What they didn't tell you is that the process actually involves Ice-9, so yeah, we're going to use up all the available liquid water and then die.
  Cool battery though.
7. Re:ALready an energy shortage there. by nschubach · 2011-05-05 03:03 · Score: 1
  
  It's a good thing that Standford isn't in the UAE then.
  
  --
  Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
8. Re:ALready an energy shortage there. by Anonymous Coward · 2011-05-05 03:04 · Score: 0
  
  He's saying that fresh water is more valuable for agriculture than for energy production. You're saying it's possible to get fresh water at a higher price-point if it's not available at a lower price-point, but that doesn't change anything -- the new water will still be preferably used for agriculture.
9. Re:ALready an energy shortage there. by wjousts · 2011-05-05 03:05 · Score: 1
  
  From TFA:
  
  In fact, the fresh water doesn't have to come from a river. Cui says that storm runoff, gray water, or even treated sewage water could potentially be used. As an added benefit, the mixing entropy process can be reversed to produce drinking water by removing salt from ocean water.
  So potable water isn't necessarily needed.
10. Re:ALready an energy shortage there. by h4rr4r · 2011-05-05 03:08 · Score: 1
  
  They could easily have free/nearly so fresh water for everyone, but those areas are generally run by less forward thinking leaders. Recently there has been some move to change that, but seems to have tapered off.
11. Re:ALready an energy shortage there. by gr8_phk · 2011-05-05 03:09 · Score: 4, Interesting
  
  I think he's talking about taking water and sending it to Arizona where it then evaporates in the desert and doesn't actually make it to the end of the river. I'm guessing of course. But as for these "inexhaustible" supplies under ground, you should read about the supply in the midwest which requires drilling to new depths because it is being depleted. Should you think going deeper is always an option, you may want to read the recent stuff of fracking to see how the deeper water is being deliberately contaminated. There are solutions to these, problems, but what we are doing vs what we could be doing don't really match.
12. Re:ALready an energy shortage there. by pla · 2011-05-05 03:22 · Score: 1
  
  Wait, you actually think water is disappearing, going poof? Where do you think this water is going?
  
  You might want to Google "photosynthesis". Major rivers no longer reach the ocean because we've diverted them for use in industrial agriculture. And yes, that water really does cease to exist as water.
  
  Of course, realistically, most of it ends up going to waste, either soaking into the ground or evaporating; Yes, we can theoretically reduce those losses drastically, but as it stands, for both human consumption and TFA's electrical generation purposes, we no longer have access to that water in any meaningful, useful way.
13. Re:ALready an energy shortage there. by seededfury · 2011-05-05 03:29 · Score: 1
  
  My first thought was they build a desalination plant right next door that operates off hydro or solar power.....
14. Re:ALready an energy shortage there. by tixxit · 2011-05-05 04:33 · Score: 1
  
  I'm sorry, but how?
15. Re:ALready an energy shortage there. by Candid88 · 2011-05-05 04:34 · Score: 1
  
  Ground water isn't a closed system in any sense. If water is taken from an aquifer at a rate greater than it is replenished then the level of the aquifer will fall and even temporarily dry up until the water levels can replenish, this could take a months, years or even centuries dependent on local geography and climate.
  In many places, aquifer depletion is a major engineering obstacle necessitating boreholes to be drilled ever deeper to maintain their rate of water extraction until the point they are simply no longer economic to operate and a new aquifer must be found.
16. Re:ALready an energy shortage there. by QRDeNameland · 2011-05-05 04:46 · Score: 1
  
  My first thought was they build a desalination plant right next door that operates off hydro or solar power.....
  Solar may be plausible...but I think there's a major flaw in the idea of a hydro-powered desalinization plant: places that have enough flowing river water for hydro don't need desalinization plants.
  
  --
  Momentarily, the need for the construction of new light will no longer exist.
17. Re:ALready an energy shortage there. by h4rr4r · 2011-05-05 04:59 · Score: 1
  
  The same way roads and all other government projects are funded.
  Excluding the UAE, most of the middle east could easily fund such projects with a tax on exported oil. Not all UAE nations export enough oil, so they could then have their various sheiks pay for it. Desalination is a well understood technology.
  Truthfully though, these nations have other problems perhaps even more pressing. By that I mean the political issues that have created the current situation to begin with.
18. Re:ALready an energy shortage there. by Amouth · 2011-05-05 05:03 · Score: 1
  
  i'm not sure personally but i have a feeling that if they focus their interest in providing fresh water rather than other crap
  http://www.dailymail.co.uk/sciencetech/article-1094797/Worlds-refrigerated-BEACH-built-luxury-hotel-Dubai.html
  just an example.... i'm sure if they refocused their efforts they could solve the problem.. but again its all about priorities.
  
  --
  '...if only "Jumping to a Conclusion" was an event in the Olympics.'
19. Re:ALready an energy shortage there. by Ferzerp · 2011-05-05 07:02 · Score: 1
  
  I said you can extract if faster than it is replinished, but it really is inexhaustable. You will not run out. Once the reserve is gone, you can only get it as fast as it seeps down, but it isn't *gone*
  The point of the post was that people are far too accepting of the concept that *everything* is scarce. Water just isn't one of those things.
  The planet will not run out of water. It just isn't going to happen. Sure, we might have to move usage around a bit in some cases, but the idea that water will magically disappear is preposterous.
20. Re:ALready an energy shortage there. by Reality+Master+101 · 2011-05-05 07:06 · Score: 0
  
  You might want to Google "photosynthesis". Major rivers no longer reach the ocean because we've diverted them for use in industrial agriculture. And yes, that water really does cease to exist as water.
  Well... no. You might say that technically the water does "cease to exist as water" since photosynthesis converts water and CO2 into sugar and oxygen. But combustion of the sugar converts it back into water and CO2, so the water is just locked up temporarily until the sugar is metabolized. It will eventually make it back into the water cycle. Water is a very, very stable molecule, and sugar is not (if it was, it wouldn't be a very good fuel).
  
  --
  Sometimes it's best to just let stupid people be stupid.
21. Re:ALready an energy shortage there. by NayDizz · 2011-05-05 08:24 · Score: 1
  
  Ewww, you mean I'm drinking dinosaur piss?
22. Re:ALready an energy shortage there. by mr_mischief · 2011-05-05 15:53 · Score: 1
  
  If you've ever had tap water from a town along the Mississippi River, you're probably drinking some thousands of other humans' piss. Possibly even you own, if you drive south along the river. Towns on big rivers don't drill for water. They treat the river water for drinking, then treat the sewage and release it back into the river.
23. Re:ALready an energy shortage there. by Candid88 · 2011-05-05 21:47 · Score: 1
  
  The water won't be *gone*, but once it's left the aquifer and flowed into the sea it's a heck of a lot less useful than when it was back in the aquifer. Also, it depends on your opinion on what counts as "replenished", the Nubian Sandstone Aquifer System under the Sahara for example ain't going to be replenishing any century soon.
24. Re:ALready an energy shortage there. by tixxit · 2011-05-06 01:43 · Score: 1
  
  Desalination is far from solved (as an economically viable technology). Yes, it works well for cruise ships and the like, but providing clean water to 10s of millions of people living in poverty? Not really. The best method for desert dwellers is to tap into fossil water supplies. Gadhafi (yes, that Gadhafi) put $30b into a water distribution and supply system that tapped into fossil water wells in the main desert and supply it all over the country. The only problem is that fossil water wells do not regenerate as fast as we use them and suffer the same fate as oil; cost goes up as more water comes out because the levels go down and it becomes harder to pump. These sources are not a permanent fix and $30b is a LOT of money for a lot of countries. Importing water isn't easy either. Water weighs a lot and costs a lot to import and, remember, we are talking about countries with millions of people with next to no GDP. Unfortunately, you are using a very wealthy nation as your example, but I'm talking about the Chads, Sudans, Nigers of the world, not the Dubais and Saudi Arabias.
yea by Osgeld · 2011-05-05 02:21 · Score: 1

so does the one in my lawnmower, I thought lead acid batteries have been around a while, maybe I just live in the future
1. Re:yea by Anonymous Coward · 2011-05-05 02:45 · Score: 0
  
  salty water in a lead acid battery?
2. Re:yea by Anonymous Coward · 2011-05-05 02:50 · Score: 0
  
  Who said anything about lead acid batteries ?
3. Re:yea by abarrow · 2011-05-05 03:02 · Score: 1
  
  But, but, this has the word "nano" in it! It has to be good!
  http://www.google.com/trends?q=nano&ctab=0&geo=all&date=all&sort=0
4. Re:yea by Osgeld · 2011-05-05 05:27 · Score: 1
  
  its rechargeable and uses water, the title of this article makes that sound like a break through innovation, the method described is, but the title is dumb
5. Re:yea by Osgeld · 2011-05-05 05:29 · Score: 1
  
  it was in response to the dipshit title, not the article
  or I meant woosh!
WARNING by Skal+Tura · 2011-05-05 02:28 · Score: 2

It's gizmag ... Prepare to be annoyed with ads

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1. Re:WARNING by camperdave · 2011-05-05 02:31 · Score: 2
  
  Thanks for the warning. I was about to Read The Fancy Article.
  
  --
  When our name is on the back of your car, we're behind you all the way!
2. Re:WARNING by hitmark · 2011-05-05 03:34 · Score: 1
  
  adblock and/or noscript for the win ;)
  
  --
  comment first, facts later. http://chem.tufts.edu/AnswersInScience/RelativityofWrong.htm
3. Re:WARNING by Sir_Eptishous · 2011-05-05 03:58 · Score: 2
  
  Oh, thats what the "F" stands for...
  
  --
  We play the game with the bravery of being out of range
4. Re:WARNING by Anonymous Coward · 2011-05-05 09:05 · Score: 0
  
  who cares about being pc? F is for FUCK .. 'fancy' is for faggots.
5. Re:WARNING by camperdave · 2011-05-05 14:43 · Score: 1
  
  Maybe some of us think the world would be a better place if people showed a little bit more class now and again.
  
  --
  When our name is on the back of your car, we're behind you all the way!
Great News for Environment! by 0xG · 2011-05-05 02:30 · Score: 1

The mixing entropy battery could be used to build power plants at estuaries where fresh water rivers join the ocea
Never mind that river estuaries are perhaps the most environmentally sensitive areas on the planet...

--
A pox on web designers who feel that window.innerWidth == screen.availWidth
1. Re:Great News for Environment! by yarnosh · 2011-05-05 02:33 · Score: 1
  
  So you're saying we need a way to harness environmental sensitivity?
2. Re:Great News for Environment! by snookerhog · 2011-05-05 02:35 · Score: 2
  
  I would gladly trade this for the aging coal power plant that currently sits on the banks of my local estuary. I am inclined to believe that this will be better for my local environment than the coal burning.
3. Re:Great News for Environment! by Anonymous Coward · 2011-05-05 02:37 · Score: 0
  
  Because there's no possible way we could locate something that needs water except right next to the source.
4. Re:Great News for Environment! by MadKeithV · 2011-05-05 02:45 · Score: 4, Funny
  
  Toyota already did with their Prius. I think the official term is "smug".
5. Re:Great News for Environment! by wjousts · 2011-05-05 03:07 · Score: 3, Informative
  
  From TFA:
  
  Because river deltas and estuaries are sensitive environments, the Stanford team designed their battery to have minimal ecological impact. The system would detour some of a river's flow to produce power, before returning the water to the ocean. The discharge water would be a mix of river water and sea water, and released into an area where the two waters already meet.
6. Re:Great News for Environment! by Anonymous Coward · 2011-05-05 03:23 · Score: 0
  
  Never mind that river estuaries are perhaps the most environmentally sensitive areas on the planet...
  From the TFA:
  
  "Because river deltas and estuaries are sensitive environments, the Stanford team designed their battery to have minimal ecological impact. The system would detour some of a river's flow to produce power, before returning the water to the ocean. The discharge water would be a mix of river water and sea water, and released into an area where the two waters already meet."
  
  It can also run using storm run off or treated waste water. Any other concerns that were clearly already addressed?
7. Re:Great News for Environment! by Anonymous Coward · 2011-05-05 03:32 · Score: 0
  
  Ah, so we only rape the environment a little bit. I'm sure she'll be OK with that.
8. Re:Great News for Environment! by wjousts · 2011-05-05 06:07 · Score: 1
  
  Hey, she was asking for it with those sexy curving rivers.
9. Re:Great News for Environment! by cheater512 · 2011-05-05 10:17 · Score: 1
  
  Something tells me that the entire estuary will have to be blocked to generate 1/16th of the coal plant's output.
10. Re:Great News for Environment! by mr_mischief · 2011-05-05 15:55 · Score: 1
  
  Actually I heard the dealers call it "cha-ching" or something like that.
11. Re:Great News for Environment! by mr_mischief · 2011-05-05 16:36 · Score: 1
  
  By the time the Mississippi gets to the Gulf of Mexico, a large portion of it is treated waste water. Where do these people think sewage goes?
12. Re:Great News for Environment! by snookerhog · 2011-05-06 02:13 · Score: 1
  
  I prefer to see the estuary as being half full.
How long will they last? by Anonymous Coward · 2011-05-05 02:32 · Score: 0

I purchased a Water Powered Clock a few years ago and it stopped working after about a month. Hopefully this technology has progressed and these batteries will have a decent lifespan.
1. Re:How long will they last? by Anonymous Coward · 2011-05-05 02:54 · Score: 0
  
  At least you know exactly when it died
Think Smaller by retroworks · 2011-05-05 02:33 · Score: 3, Funny

Like, recharging your flashlight at the urinal.

--
Gently reply
1. Re:Think Smaller by Abstrackt · 2011-05-05 02:44 · Score: 1
  
  As a Slashdotter, I find I get more value out of one of those flashlights you have to jerk back and forth to build up a charge. ;)
  
  --
  They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance. - Terry Pratchett
2. Re:Think Smaller by Five+Bucks! · 2011-05-05 02:44 · Score: 1
  
  I have a flashlight with the dynamo that charges when you shake it. So I just charge it when I... well it's personal - but my light is always charged.
  
  --
  52 52'23" W 47 32'07" N
3. Re:Think Smaller by Anonymous Coward · 2011-05-05 03:00 · Score: 0
  
  Yeah but when you use those it isn't light coming out of the "flashlight"
4. Re:Think Smaller by Anonymous Coward · 2011-05-05 03:18 · Score: 0
  
  You're thinking too small!
5. Re:Think Smaller by Inda · 2011-05-05 03:32 · Score: 3, Funny
  
  Next week on Slashdot:
  
  New lemon orchard used to power city.
  
  Clever academics have found a way to harness the power of a standard lemon with an old copper penny and some scrap zinc. Could this scale?
  
  --
  This post contains benzene, nitrosamines, formaldehyde and hydrogen cyanide.
6. Re:Think Smaller by Anonymous Coward · 2011-05-05 04:14 · Score: 0
  
  You spelt fleshlight wrong. Also: Ewwwwwwwwwww!
7. Re:Think Smaller by DigiShaman · 2011-05-05 04:39 · Score: 1
  
  I would say to recharge the automatic flusher, but the flow of in-comming water already does that.
  
  --
  Life is not for the lazy.
8. Re:Think Smaller by uninformedLuddite · 2011-05-06 13:46 · Score: 1
  
  As a Slashdotter, I find I get more value out of one of those flashlights you have to jerk back and forth to build up a charge. ;)
  But it's only flashing if you have a webcam right?
  
  --
  The new right fascists are bilingual. They speak English and Bullshit.
Wait... by plsenjy · 2011-05-05 02:37 · Score: 1

Should I stop holding my breath for microbial fuel cells? http://news.nationalgeographic.com/news/2005/09/0909_050909_cowbattery.html

--
Glad I could help.
Is the start up called Nemo? by Anonymous Coward · 2011-05-05 02:40 · Score: 0

Jules Verne strikes again!
Just think of the possibilities! by naich · 2011-05-05 02:43 · Score: 5, Interesting

We could use the generated electricity to power desalinisation plants.
1. Re:Just think of the possibilities! by ShanghaiBill · 2011-05-05 02:57 · Score: 5, Interesting
  We could use the generated electricity to power desalinisation plants.
  I think you are trying to be funny, but this actually makes sense, and there are proposals to do exactly this. Here is how it works:
  Step 1: Concentrate brine in large evaporation ponds
  Step 2: Generate electricity from the osmotic difference between this brine and normal seawater
  Step 3: Use the electricity to split seawater into fresh water and brine
  Step 4: Recycle the brine back into the evaporation ponds
  Step 5: Profit!
  The reason this works is that you are effectively collecting the solar energy that shines on the evaporation ponds.
2. Re:Just think of the possibilities! by Xacid · 2011-05-05 03:04 · Score: 2
  
  I see what you did there...
3. Re:Just think of the possibilities! by wjousts · 2011-05-05 03:08 · Score: 1
  
  Perpetual motion FTW!
4. Re:Just think of the possibilities! by ArsenneLupin · 2011-05-05 03:14 · Score: 1
  
  I see what you did there...
  But apparently the moderators didn't...
5. Re:Just think of the possibilities! by trout007 · 2011-05-05 03:16 · Score: 3, Interesting
  
  Not that this would be ecologically feasible but what if you dug a tunnel from the pacific ocean to death valley (-300 feet). Then you could get some power out of the potential water drop. Then as the water floods the valley it's so hot it would evaporate and you could keep letting the water in. The evaporated water would rain on the next mountain down wind and create arable land.
  
  --
  I love Jesus, except for his foreign policy.
6. Re:Just think of the possibilities! by MoonBuggy · 2011-05-05 03:21 · Score: 2
  
  Interesting, but what's the advantage of this over condensing the vapour from the pools directly?
7. Re:Just think of the possibilities! by pr0nbot · 2011-05-05 03:23 · Score: 1
  
  Isn't Step 1 already splitting seawater into fresh water and brine?
8. Re:Just think of the possibilities! by Anonymous Coward · 2011-05-05 03:28 · Score: 0
  
  This has been proposed for the Quattara Depression in the Sahara. Larger and easier to reach than Death Valley - and the evaporation might water the Sahara.
9. Re:Just think of the possibilities! by robot256 · 2011-05-05 03:28 · Score: 1
  
  Perpetual motion FTW!
  Life on Earth is only perpetual until you turn off the sun.
10. Re:Just think of the possibilities! by Anonymous Coward · 2011-05-05 03:36 · Score: 0
  
  And you can sell the salt as some "gourmet brand" since it'll have a delightful mix of oceanic and desert flavors!
11. Re:Just think of the possibilities! by Cajun+Hell · 2011-05-05 03:38 · Score: 1
  
  That would give us enough salt to last forever!!
  
  --
  "Believe me!" -- Donald Trump
12. Re:Just think of the possibilities! by Thud457 · 2011-05-05 03:47 · Score: 1
  
  There's more than one energy input to the system.
  
  --
  the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
13. Re:Just think of the possibilities! by mcavic · 2011-05-05 03:55 · Score: 1
  
  Isn't Step 1 already splitting seawater into fresh water and brine?
  Yes, but you have to start with a pool of brine, to prime the pump.
14. Re:Just think of the possibilities! by DriedClexler · 2011-05-05 03:57 · Score: 1
  
  Probably be more feasible for Mediterranean -> Dead Sea, but then you'd have to tunnel through numerous archaeological sites to do it.
  
  --
  Information theory is life. The rest is just the KL divergence.
15. Re:Just think of the possibilities! by Sir_Eptishous · 2011-05-05 04:00 · Score: 1
  
  From the article: "In fact, the fresh water doesn't have to come from a river. Cui says that storm runoff, gray water, or even treated sewage water could potentially be used. As an added benefit, the mixing entropy process can be reversed to produce drinking water by removing salt from ocean water."
  
  --
  We play the game with the bravery of being out of range
16. Re:Just think of the possibilities! by Anonymous Coward · 2011-05-05 04:16 · Score: 0
  We could use the generated electricity to power desalinisation plants.
  I think you are trying to be funny, but this actually makes sense, and there are proposals to do exactly this. Here is how it works:
  
  Step 1: Concentrate brine in large evaporation ponds
  Step 2: Generate electricity from the osmotic difference between this brine and normal seawater
  Step 3: Use the electricity to split seawater into fresh water and brine
  Step 4: Recycle the brine back into the evaporation ponds
  Step 5: Profit!
  The reason this works is that you are effectively collecting the solar energy that shines on the evaporation ponds.
  Are you serious or just trying to be funny too??
  It is much simpler just to use the fresh water in the first place and it, you know, doesn't try to violate the 2nd law of thermodynamics.
17. Re:Just think of the possibilities! by ShanghaiBill · 2011-05-05 04:16 · Score: 1
  
  Interesting, but what's the advantage of this over condensing the vapour from the pools directly?
  It is orders of magnitude less expensive. If you want to condense the vapor, you first need to collect the vapor. Evaporation ponds typically cover thousands of hectares. Building an enclosure to collect the vapor over such an area would cost megabucks or even gigabucks. Once you collect the vapor you need to compress and cool it to turn it into liquid water. This is also very expensive.
  If simply evaporating seawater was a cost effective way to produce fresh water, the world would have not water shortages, and the deserts would bloom.
18. Re:Just think of the possibilities! by spikenerd · 2011-05-05 04:43 · Score: 1
  
  Why tunnel? Wouldn't a big siphon be easier to build?
19. Re:Just think of the possibilities! by Belial6 · 2011-05-05 04:53 · Score: 1
  
  Why is it that no one on Slashdot who points out the law of thermodynamics has any understanding of how it works?
20. Re:Just think of the possibilities! by Anonymous Coward · 2011-05-05 04:56 · Score: 0
  
  I think slashdot mentioned slow, long-lived single-celled organisms that can survive on just liquid water, I suppose some carbon and nitrogen compounds, and alpha-particle radiation. Not sure if radioactive decay could keep pockets of water liquid, but if so, the sun wouldn't be needed until the water in that region was depleted. I think they may have even produced their own oxygen from alpha-particles splitting water molecules.
21. Re:Just think of the possibilities! by Anonymous Coward · 2011-05-05 04:59 · Score: 3, Funny
  
  San Andreas Fault thinks your tunneling is cute.
22. Re:Just think of the possibilities! by Solandri · 2011-05-05 05:09 · Score: 1
  
  * Step 1: Concentrate brine in large evaporation ponds
  * Step 2: Generate electricity from the osmotic difference between this brine and normal seawater
  * Step 3: Use the electricity to split seawater into fresh water and brine
  * Step 4: Recycle the brine back into the evaporation ponds
  * Step 5: Profit!
  
  The reason this works is that you are effectively collecting the solar energy that shines on the evaporation ponds.
  No it doesn't work. Well, it would work, but it'd be less effective than simply running an evaporation pond.
  
  The solar energy you're collecting in step 1 gets stored in the decreased entropy of the brine (call it pool 1). Steps 2-4 is simply converting that decreased entropy to electricity, which is used to decrease the entropy in a different pool of water (pool 2). However, since this is done at the cost of increasing entropy in pool 1, you're simply transferring entropy from pool 2 to pool 1. Best case you'd do this with 100% efficiency. But since thermodynamics doesn't allow 100% efficiency, you're better off if you simply dumped pool 2's water into pool 1, allowed it to evaporate, and ran the moisture-laden air through a condenser to extract the fresh water.
  
  If anyone is trying this for real, I suspect it's because step 3 (use electricity to split seawater into fresh water and brine) may be easier than covering your evaporation pond with clear plastic and running the moisture-laden air through a condenser. i.e. It's a higher energy cost solution (which doesn't really matter if you're getting your energy free from the sun), but a lower construction cost solution. Distributed systems (covering the evaporation ponds) tend to have high construction and maintenance costs (the bane of PV) relative to concentrated systems (a reverse osmosis filter system pressurized by electric pumps).
23. Re:Just think of the possibilities! by mr.mctibbs · 2011-05-05 05:16 · Score: 1
  
  You're still creating perpetual-motion machine here. The resource we are using energy to create with desalination is the fresh water. The resource we are consuming to create electricity osmotically is the fresh water, not the brine. Creating brine with evaporation doesn't feed energy into this loop, so it's still a closed cycle.
24. Re:Just think of the possibilities! by Isaac-1 · 2011-05-05 05:28 · Score: 1
  
  Siphons have a maximum theoretical height limit relating to the minimum pressure inside at the peak. Simply put when the pressure gets low enough to boil water at ambient temperature then the siphon no longer works.
25. Re:Just think of the possibilities! by idji · 2011-05-05 06:21 · Score: 1
  
  You perhaps forgot the energy costs of dredging the salt out of your pond when it gets too shallow.
26. Re:Just think of the possibilities! by SEWilco · 2011-05-05 06:34 · Score: 2
  
  Because, of course, if your fresh/salt water plant is next to a fresh water river, there isn't any source of fresh water nearby, so you have to desalinate the salt water.
27. Re:Just think of the possibilities! by Anonymous Coward · 2011-05-05 06:41 · Score: 0
  
  There are places in the world where the canals would be feasible for this. I think the Valdez Peninsula in Argentina and the Qattara Depression in Egypt are examples. Death Valley has too many mountains in the way. The Salton Sea is also below sea level, but we already dug the channel to that valley a hundred years ago, irrigated the land, and built Mexicali and Imperial County on the land.
28. Re:Just think of the possibilities! by minorproblem · 2011-05-05 06:50 · Score: 1
  
  I think its easier to have acres and acres of solar collectors than it is to build a structure over the top of that.
29. Re:Just think of the possibilities! by Anonymous Coward · 2011-05-05 07:05 · Score: 0
  
  I assume the evaporated fresh water would be collected above the ponds?
30. Re:Just think of the possibilities! by ArsonSmith · 2011-05-05 07:29 · Score: 0
  
  http://xkcd.com/386/
  It's the weight of the water vs the external pressure pushing on the water. A vacuum can lift different fluids to different heights based on their weight. Mercury is about 30" at sea level, water is about double that.
  
  --
  Paying taxes to buy civilization is like paying a hooker to buy love.
31. Re:Just think of the possibilities! by robot256 · 2011-05-05 08:49 · Score: 1
  
  Except that by the time the sun burns out, the Earth's core will be long-dead.
32. Re:Just think of the possibilities! by DirePickle · 2011-05-05 10:27 · Score: 2
  
  The first law of thermodynamics is you don't talk about thermodynamics.
33. Re:Just think of the possibilities! by mr_mischief · 2011-05-05 16:41 · Score: 1
  
  Did you know that the laws of thermodynamics relate to closed systems?
  Did you know that the energy of the sun shining on thousands of hectares is an input from outside this system?
  Did you know your condescension post is a big pile of FAIL?
34. Re:Just think of the possibilities! by trout007 · 2011-05-12 01:49 · Score: 1
  
  Thanks for the links. That is pretty cool stuff. It seems people are worries about increased salinity in the man made sea. But the Mediterranean Sea managed to balance this due to the difference density of ocean water and the sea water. If you made another tunnel that led from the bottom of the lake to an equivalent depth in the ocean you could let saltier water out into the ocean.
  
  --
  I love Jesus, except for his foreign policy.
Isn't this already in practice elsewhere??? by dr.Flake · 2011-05-05 02:45 · Score: 4, Informative

I know the plans to put one of these into service are almost finalized in The Netherlands, spanning the "afsluitdijk"
http://wikimobi.nl/wiki/index.php?title=Zoet/zout_watergrens
But i think the Norwegians beat us all to it:
http://www.statkraft.com/energy-sources/osmotic-power/

--
Why are other peoples sig's always more witty ???
1. Re:Isn't this already in practice elsewhere??? by arielCo · 2011-05-05 03:06 · Score: 2
  
  Depends on how wide your definition of "this" is. Let's quote TFA for convenience:
  
  Making electricity from the difference in salinity (the amount of salt) in fresh water and sea water is not a new concept. We've previously covered salinity power technology, and Norway's Statkraft has built a working prototype power plant. But the Stanford team, led by associate professor of materials science and engineering Yi Cui, believes their method is more efficient, and can be built more cheaply.
  
  --
  This post contains no rudeness or derision of any kind. All arguments are friendly. Terms and exclusions may apply.
2. Re:Isn't this already in practice elsewhere??? by wjousts · 2011-05-05 03:09 · Score: 5, Funny
  
  ...spanning the "afsluitdijk".
  Cat just jump on your keyboard?
3. Re:Isn't this already in practice elsewhere??? by Dr.+Cody · 2011-05-05 04:57 · Score: 3, Funny
  
  ...spanning the "afsluitdijk".
  Cat just jump on your keyboard?
  Appropriately enough, the language sounds like a cat expectorating a hairball.
4. Re:Isn't this already in practice elsewhere??? by Isaac-1 · 2011-05-05 05:30 · Score: 1
  
  How did you just guess the password to my credit card accounts?
5. Re:Isn't this already in practice elsewhere??? by rawler · 2011-05-05 05:42 · Score: 1
  
  TFA explicitly mentions the Statkraft project. However, there seems to be a significant difference between the two; where statkraft is using the salinity to create pressure and power a conventional turbine generator, this article is about creating current directly, which should theoretically improve efficency a lot.
  According to TFA a, 50cubic meter/second flow of fresh water could yield up to 100MW.
6. Re:Isn't this already in practice elsewhere??? by Anonymous Coward · 2011-05-05 08:33 · Score: 0
  
  Gezellig!
7. Re:Isn't this already in practice elsewhere??? by Anonymous Coward · 2011-05-06 00:11 · Score: 0
  
  Pronounced something like ahf-sloit-dike /offtopic
8. Re:Isn't this already in practice elsewhere??? by Anonymous Coward · 2011-05-06 01:25 · Score: 0
  
  it's a combination of three separate words:
  "af", "sluit" and "dijk"
  with:
  "ui" and "ij" being Diphthongs
  Diphthong, also known as a gliding vowel, refers to two adjacent vowel sounds occurring within the same syllable. Technically, a diphthong is a vowel with two different targets: That is, the tongue moves during the pronunciation of the vowel. In most dialects of English, the words eye, hay, boy, low, and cow contain diphthongs.
  https://secure.wikimedia.org/wikipedia/en/wiki/Diphthong
9. Re:Isn't this already in practice elsewhere??? by wjousts · 2011-05-06 02:37 · Score: 1
  
  ZZZZZZzzzzzzzzzzzzzzzzz. Sorry, I drifted off there.
Bass Akwards! by CatsupBoy · 2011-05-05 02:51 · Score: 3, Insightful

After the battery is discharged, the salt water is drained and fresh water is added to begin the cycle again.
This is awesome, we can use up all our fresh water and would have an unlimited supply of salt water!
1. Re:Bass Akwards! by Attila+Dimedici · 2011-05-05 03:06 · Score: 1
  
  You do know that there is an amazingly simple way to separate the salt from the water, right? It is called evaporation.
  
  --
  The truth is that all men having power ought to be mistrusted. James Madison
2. Re:Bass Akwards! by CatsupBoy · 2011-05-05 03:11 · Score: 3, Insightful
  
  You do know that there is an amazingly simple way to separate the salt from the water, right? It is called evaporation.
  The concepts of desalination are certainly quite simple, its the economics that are complicated.
3. Re:Bass Akwards! by JSBiff · 2011-05-05 03:32 · Score: 1
  
  This certainly wouldn't be appropriate everywhere. But, consider the Mississipi River Delta. It's dumping massive amounts of fresh water into salt water anyhow.
  It hardly seems like diverting a small percentage of the fresh water being dumped into the ocean by nature, extracting power from it as it gets salty, then dumping the brackish water from the power plant into the ocean, in any reasonable way reduces the fresh water supply, does it?
  Or, do you propose that we completely dam up the Mississippi so we don't "use up" all our fresh water?
4. Re:Bass Akwards! by Anonymous Coward · 2011-05-05 03:40 · Score: 0
  
  This is awesome, we can use up all our fresh water and would have an unlimited supply of salt water!
  The problem is far worse than you can imagine. We are dumping literally billions of tons of fresh water into the oceans each year. Pretty soon there will be nothing left!
5. Re:Bass Akwards! by timeOday · 2011-05-05 05:52 · Score: 1
  
  Good lord, they headed off that complaint right in the summary, and it still wasn't enough.
6. Re:Bass Akwards! by LateArthurDent · 2011-05-05 06:35 · Score: 2
  
  You do know that there is an amazingly simple way to separate the salt from the water, right? It is called evaporation.
  The concepts of desalination are certainly quite simple, its the economics that are complicated.
  He means natural evaporation. Oceans are under the Sun all the time. You can't "use up" fresh water by intercepting water that's about to fall on the ocean and making it into salt water. That is happening all the time anyway, those rivers are constantly dumping fresh water into the ocean. Luckily, water evaporates off the oceans and comes back down as fresh water as rain, filling up those rivers and continuing the cycle.
7. Re:Bass Akwards! by Anonymous Coward · 2011-05-05 08:10 · Score: 0
  
  I think you fail to understand how much of a shortage there is of fresh water.
  
  That is happening all the time anyway, those rivers are constantly dumping fresh water into the ocean.
  
  Many rivers no longer reach the ocean, because they are entirely consumed before that. Others have a tiny quota that is not consumed so that there's still some natural flow, but there's no "extra" left over for converting to power.
8. Re:Bass Akwards! by Anonymous Coward · 2011-05-06 02:19 · Score: 0
  
  I think you fail to understand how much of a shortage there is of fresh water.
  There is no such thing as a global shortage of fresh water. That would go against the laws of physics. We're not destroying water in the planet. There's a huge amount of water in the ocean even if those rivers don't reach it, which means that water is still evaporating and falling as fresh water elsewhere. There is, of course, such a thing as a local shortage of fresh water. It's not economically feasible to build such things in places where fresh water is not abundant, so you don't have to worry about it.
Not to be all green but... by medv4380 · 2011-05-05 02:51 · Score: 1

This sounds like something that would just finish off the migrating salmon population if implemented.
1. Re:Not to be all green but... by nschubach · 2011-05-05 03:02 · Score: 1
  
  Salmon aren't needed. Only water. ;)
  
  --
  Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
2. Re:Not to be all green but... by TheRaven64 · 2011-05-05 05:34 · Score: 1
  
  If you do it right, you get electricity and smoked salmon as the two outputs.
  
  --
  I am TheRaven on Soylent News
3. Re:Not to be all green but... by Anonymous Coward · 2011-05-06 16:02 · Score: 0
  
  If you do it right, you get electricity and smoked salmon as the two outputs.
  How did this not get modded +11 funny? Mmmmm, lox.
how new is this? by metalmaster · 2011-05-05 02:53 · Score: 1

Im getting a sort of deja vu feeling because i'd swear i've heard of this, or a similar, process before.
Can we get a comparison to hydroelectric? by chemicaldave · 2011-05-05 02:54 · Score: 1

The Stanford team has calculated that with 50 cubic meters (more than 13,000 gallons) of fresh water per second, a power plant based on this technology could produce up to 100 megawatts of power.
I can't find any facts detailing the flow of water through various hydroelectric dam turbines to compare to this, but 100MW from 50m^3/s seems very efficient.
1. Re:Can we get a comparison to hydroelectric? by Anonymous Coward · 2011-05-05 03:16 · Score: 0
  
  According to Google Calculator, this is equivalent to a 200m high hydroelectric dam.
2. Re:Can we get a comparison to hydroelectric? by Anonymous Coward · 2011-05-05 03:31 · Score: 0
  
  Wikipedia says:
  P = hrgk
  where P is Power in kilowatts, h is height in meters, r is flow rate in cubic meters per second, g is acceleration due to gravity of 9.8 m/s2, and k is a coefficient of efficiency ranging from 0 to 1.
  For three gorges dam, h=80.6 m, k = .9, and with the given 50m/s comes out to about 35.5 MW.
  So yes, lots of power, almost 3 times as efficient as a modern hydroelectric and doesn't require a specific location with a large drop in height. But right now that efficiency is only calculated. We'll see what it's comes out as once you change the electrodes to something cheaper and take into account, pumping and everything else not needed in a hydroelectric plant.
3. Re:Can we get a comparison to hydroelectric? by Anonymous Coward · 2011-05-05 04:23 · Score: 0
  
  A simple formula for approximating electric power production at a hydroelectric plant is: P = hrgk, where
  * P is Power in watts,
  * is the density of water (~1000 kg/m3),
  * h is height in meters,
  * r is flow rate in cubic meters per second,
  * g is acceleration due to gravity of 9.8 m/s2,
  * k is a coefficient of efficiency ranging from 0 to 1. Efficiency is often higher (that is, closer to 1) with larger and more modern turbines.
  https://secure.wikimedia.org/wikipedia/en/wiki/Hydroelectricity
  I did your Google search (and felt lucky). You do the math.
4. Re:Can we get a comparison to hydroelectric? by Anonymous Coward · 2011-05-05 08:50 · Score: 0
  
  The Stanford team has calculated that with 50 cubic meters (more than 13,000 gallons) of fresh water per second, a power plant based on this technology could produce up to 100 megawatts of power.
  I can't find any facts detailing the flow of water through various hydroelectric dam turbines to compare to this, but 100MW from 50m^3/s seems very efficient.
  Probably because the flow rate isn't the only variable - you also need to take into account the height of the dam.
  A simple formula for approximating electric power production at a hydroelectric plant is: P = phrgk, where
  P is Power in watts,
  p is the density of water (~1000 kg/m3),
  h is height in meters,
  r is flow rate in cubic meters per second,
  g is acceleration due to gravity of 9.8 m/s2,
  k is a coefficient of efficiency ranging from 0 to 1. Efficiency is often higher (that is, closer to 1) with larger and more modern turbines.
  100000000 = 1000*h*50*9.8*k
  So h*k = ~204, so this is comparable to a highly efficient damn roughly 200+m high. Dams that big are generally in the GW range (e.g. Grand Coulee, the largest in the US has an installed capacity of just under 7GW and is 168m high).
Just like a potato battery... by Overzeetop · 2011-05-05 02:57 · Score: 1

It looks like a potato battery (that we used to make little clock kits back in the 80s) or any galvanic battery dating back 100+ years, but with a tweak to get more out of it, implemented on a larger scale, and slapped with a "New and Improved, now with NANOTECHNOLOGY" sticker.

--
Is it just my observation, or are there way too many stupid people in the world?
Also deep wells by scharkalvin · 2011-05-05 02:58 · Score: 2

In Florida most drinking water is obtained from wells. Deep wells tend to be brackish and require desalination of the water to be usable. It would seem then that a combination use of waste water and deep well water would work. Also the battery sounds like it acts as a desalination device during discharge so it might serve the purpose of both desalination and power generation.
1. Re:Also deep wells by zpiro · 2011-05-05 03:14 · Score: 1
  
  From reading the article, you add fresh water first;
  then salt water -- the saltier the better -- this stage giving you the power
  
  Then you start the cycle over again, cleaning out and adding fresh water.
  
  No desalination of water involved, unless creating more brackish water is what you want.
  
  Bad news for those without excessive access to fresh water near the coast.
  
  But would be interesting to know how clean the water needs to be -- tolerance for pollutants.
2. Re:Also deep wells by Nidi62 · 2011-05-05 03:24 · Score: 1
  
  In Florida most drinking water is obtained from wells. Deep wells tend to be brackish and require desalination of the water to be usable.
  So that explains why Florida has some of the worst-tasting drinking water in the entire country.
  
  --
  The only thing necessary for evil to triumph is for it to be pitted against a slightly greater evil
3. Re:Also deep wells by Anonymous Coward · 2011-05-05 07:07 · Score: 0
  
  That is so true. The first time I went to Florida and took a shower there and some water got into my mouth, I went down stairs to ask if sewage got into our pipes. It literally tastes like stagnant water, not just tastes, it smells the part too.
4. Re:Also deep wells by RivenAleem · 2011-05-08 23:21 · Score: 1
  
  Why do you think they grow so many oranges?
Hurray for environmentalists by DNS-and-BIND · 2011-05-05 03:23 · Score: 1, Insightful

Ever wonder why environmentalists have such a bad name? Here's a new concept and they're already shooting it down, based on nothing more than a vague assertion.

--
Shutting down free speech with violence isn't fighting fascism. It IS fascism!
1. Re:Hurray for environmentalists by hedwards · 2011-05-05 03:37 · Score: 0, Troll
  
  Environmentalists have a bad name because the industries that are doing all the damage find character assassination easier than actually cleaning up their mess. And much of the anti-environmentalist movement is made up of people that believe that God would never allow for more flooding because the Bible doesn't say anything about another great flood. Or are so self centered as to think that they don't have any sort of social responsibility for the next several generations.
2. Re:Hurray for environmentalists by DNS-and-BIND · 2011-05-05 03:52 · Score: 1
  
  Well, that certainly excuses relentless negativism and theophobia. Well-played! Please continue the campaign of shitting all over solutions.
  
  --
  Shutting down free speech with violence isn't fighting fascism. It IS fascism!
3. Re:Hurray for environmentalists by ep32g79 · 2011-05-05 04:18 · Score: 2
  
  Environmentalists have a bad name because the industries that are doing all the damage find character assassination easier than actually cleaning up their mess.
  Rigggght.... It's all a big conspiracy against environmentalists perpetrated by the big bad corporations. Environmentalists have never done anything to damage their own character
4. Re:Hurray for environmentalists by Belial6 · 2011-05-05 04:42 · Score: 2
  
  I have never met a single person that identified themselves as an environmentalist that actually was one. Every single person I have met that actually was an environmentalist would not self identify as one.
5. Re:Hurray for environmentalists by skids · 2011-05-05 05:11 · Score: 1
  
  Parent is more likely just plain old contrarian, than "environmentalist."
  
  --
  Someone had to do it.
6. Re:Hurray for environmentalists by Anonymous Coward · 2011-05-05 07:28 · Score: 0
  
  Thank you for doing your part on giving environmentalists a bad name.
7. Re:Hurray for environmentalists by PoopJuggler · 2011-05-05 08:27 · Score: -1
  
  Well, it's the same with terrorists.
8. Re:Hurray for environmentalists by mr_mischief · 2011-05-05 16:34 · Score: 1
  
  Companies that make useful goods and provide useful services have a bad name because the environmentalists that are doing all the lobbying find character assassination easier than actually suggesting alternatives. And much of the anti-corporate movement is made up of people that believe The Government would never allow for more starvation because the Welfare Act doesn't say anything about more starvation. Or are so self centered as to think that they don't have any sort of debt of gratitude to the past several generations for keeping them out of mud huts and scavenging tribes.
  See? It's easy to write a diatribe. Now, how do we keep people housed, clothed, and fed with less negative impact on the environment?
9. Re:Hurray for environmentalists by internettoughguy · 2011-05-06 01:01 · Score: 1
  
  But won't someone think of the sea kittens!
10. Re:Hurray for environmentalists by uninformedLuddite · 2011-05-06 13:45 · Score: 1
  
  Environmentalists have a bad name because the industries that are doing all the damage find character assassination easier than actually cleaning up their mess.
  Rigggght.... It's all a big conspiracy against environmentalists perpetrated by the big bad corporations.
  And propagated by complete tosspots
  
  --
  The new right fascists are bilingual. They speak English and Bullshit.
The Silver Electrode is very expensive? by davonshire · 2011-05-05 03:23 · Score: 2

From the article:
"The Stanford scientists are currently working on modifications to get the battery ready for commercial production. For example, the silver electrode is very expensive, and they hope to develop a cheaper alternative."
I'm really at a loss on this. How expensive can a silver electrode be, if you're producing enough power to charge for it? Silver while pricey (currently ~ $39.00/oz) It's just a tad more expensive than Lithium (currently ~ $31.50/oz) and if this thing really worked. they'd pay for the silver they used in a very short order. 50Megawatt would be around $3000.00 / hr at just $0.06/kwh.
It's gotta be cheaper than building a power plant and running coal to it all day.
Just my 6 cents worth.
DS
1. Re:The Silver Electrode is very expensive? by hedwards · 2011-05-05 03:41 · Score: 0
  
  Coal is less about cheap than it is about our war on the environment and rewarding corporations with the deepest pockets. In some places like Texas the coal power isn't any cheaper than other forms of power are.
2. Re:The Silver Electrode is very expensive? by Belial6 · 2011-05-05 05:00 · Score: 1
  
  Are you really suggesting that Coal plants are being run for the specific purpose of destroying the environment with electricity being a useful byproduct?!?!?
3. Re:The Silver Electrode is very expensive? by Anonymous Coward · 2011-05-05 09:25 · Score: 0
  
  The post you replied to is almost unintelligible, but I'm guessing he means that if the hidden costs of coal (environmental damage, etc) were included then a free market would not chose to use coal in places like Texas where it makes no sense to be burning coal. What many people here seem to fail to realize is this proposed technology will also have hidden environmental costs. Coastal ecosystems where fresh water meets sea water are very sensitive places.
Wouldn't this "leach" material from the electrodes by ArsenneLupin · 2011-05-05 03:27 · Score: 1
Wouldn't this "leach" material from the electrodes into the water?
Normally, batteries work by leaching material from one electrode into the water, while precipitating ions on the other. By draining the battery, you actually "consume" one of the electrodes. Recharging work if the process can be reversed.
However, if the electrolyte is changed between charging and decharging, effectively the manganese dioxide or silver ions dissolved are now gone, which has two effects:
- pollution
- electrode whose ions are gone cannot regenerate
It could work with ions naturally present in water (such as the sodium from the salt...). Unfortunately, however, a sodium electrode dipped in water would make a nice firework, but not a battery...
On a commercial scale? by JSBiff · 2011-05-05 03:28 · Score: 1

I think what's new isn't the basic science, but the R&D to try to scale this up to commercial size power plants?
Still, I can't help but think that at some point, this is going to create contention somewhere between some peoples' need for fresh water, and other peoples' need for electricity.
I guess the idea is that places like the Mississippi Delta where a lot of fresh water is just dumping into the ocean (and being "wasted") *anyhow*, it wouldn't hurt to put such a power plant.
I'm surpised nobody has noted this alternative by Thud457 · 2011-05-05 03:38 · Score: 1

who needs fresh water when you can use pee ?!!!

--
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
1. Re:I'm surpised nobody has noted this alternative by kheldan · 2011-05-05 03:58 · Score: 1
  
  who needs fresh water when you can use pee ?!!!
  This comment sponsored by Bear Gryllis
  
  --
  Are YOU using the TOOL, or is the TOOL using YOU? Think about it!
Congrats, props from me by DriedClexler · 2011-05-05 03:40 · Score: 2

In learning about thermodynamics I had learned that, where there's a gradient, you can extract energy, be it a gradient of temperature, electrical field ... or even chemical concentration. But it's one thing to know it's theoretically possible, and another thing to actually pull it off in a way that extracts meaningful energy. Good work, scientists and engineers.

--
Information theory is life. The rest is just the KL divergence.
1. Re:Congrats, props from me by Belial6 · 2011-05-05 05:04 · Score: 2
  
  You comment is funny for me. Just a bit ago I posted a comment about how every single person who brings up thermodynamics on Slashdot doesn't know what it means. And then here I find, possibly the first, comment about thermodynamics on Slashdot with a an actual clue.
  
  Well done.
2. Re:Congrats, props from me by DriedClexler · 2011-05-05 05:56 · Score: 2
  
  Glad to hear it! But I didn't know I was saying something all that insightful or demonstrative of thermodynamics understanding.
  It is kind of counterintuitive that you'd be able to extract energy just because there's a difference in concentration between two bodies, but it makes more sense once you've read about the Gibbs paradox (esp. Jaynes's handling) and how you can power a mechanical device by using membranes that differ in their permeability to the different constituents of the mixture.
  But man, if even that level of understanding is rare for thermo, God help us all (in the secular sense).
  
  --
  Information theory is life. The rest is just the KL divergence.
Re:Think dick. by Anonymous Coward · 2011-05-05 03:45 · Score: 0

As a Slashdotter, I find I get more value out of one of those fleshlights you have to jerk back and forth to build up a charge. ;)
Charge ahead!
Consumables? by RightwingNutjob · 2011-05-05 03:50 · Score: 1

Will this magic power plant at the side of the ocean require new electrodes/new electrodes every few hours because of pitting and erosion, just like normal batteries?
Re:Wouldn't this "leach" material from the electro by leuk_he · 2011-05-05 03:51 · Score: 1

Isn't the chlorine the material that is exchanged? Not the actual electrodes?
If it works ... by Anonymous Coward · 2011-05-05 03:58 · Score: -1

some green conehead will probably complain about the quality of the water going into the ocean ( too salty, too munch entropy, too something ).
As always, it's a scale problem. by tacokill · 2011-05-05 04:05 · Score: 4, Informative

So, 13,000 gallons per second of fresh water flow and we can get around 100MW. Let's go on a math exercise, shall we?

The average combined cycle plant is (at a minimum) around 400MW. Not including co-gens, etc. Just normal power plants sitting out in the middle of nowhere. Fukishima is around 4900MW. Fukishima isn't really fair because it is, by any measure, a large nuke plant. But, 400-1200MW is not an unreasonable range for "typical" power plants in the US, regardless of the technology used (coal, nuke, combined cycle, direct fire, etc)

At 400MW, you are talking 52,000 gallons PER SECOND of water flow. That, by any measure, is a shitload of flow. At 1200MW, we are talking 156,000 gallons per second.

For comparison, I just looked up the flow rate of the Mississippi river at the high water dam near Lake Itasca. Going thru the Upper St Anthony's falls lock and dam, the flow rate is around 90,000 gal/sec.

So for ONE reasonably sized power plant, you would need fresh water flow that is the equivalent of the Mississippi River.

As I said, it's a scale problem.
1. Re:As always, it's a scale problem. by steelfood · 2011-05-05 04:35 · Score: 1
  
  In comparison, the hoover dam generates 2.08 GW, and niagara falls 2.4 GW. And in the most extreme case, the three gorges dam does 18.2 GW.
  It may work on small scales, but it cannot compete with hydroelectric on a large scale.
  
  --
  "If a nation expects to be ignorant and free in a state of civilization, it expects what never was and never will be."
2. Re:As always, it's a scale problem. by gurudyne · 2011-05-05 04:53 · Score: 2
  
  Uh, you are looking through the telescope the wrong way. That flow you quoted is at the UPPER end. From the same site you linked to, the flow is 50 times greater at the Delta, where you find the OTHER side of the cell, salt water.
  
  --
  Hey, Mom! Is it beer, yet?
3. Re:As always, it's a scale problem. by Anonymous Coward · 2011-05-05 05:11 · Score: 0
  
  Just thought I would point out that the volume of the Mississippi is the smallest near the source......Not disagreeing the point .
4. Re:As always, it's a scale problem. by Anonymous Coward · 2011-05-05 06:15 · Score: 0
  
  The flow rate at the delta (New Orleans) is actualls 4,493,400 gallons per second
  600,000 ft3/s * 7.489 g/ft3 = 4,493,400 g/s ...
  4,493,400 g/s * (100MW / 13,000g/s) = 34,564MW of raw generating capacity
  Of course you can't use 100% of raw capacity or anything near it without significant ecological and industrial impact so if you assume you can leach 5% of flow then you can produce 1728MW from the Mississippi river delta in New Orleans. Sounds like an average to above average power plant... and worth pursuing.
  Numbers taken from http://www.nps.gov/miss/riverfacts.htm
  Volume
  At Lake Itasca, the average flow rate is 6 cubic feet per second. At Upper St. Anthony's Falls, the northern most Lock and Dam, the average flow rate is 12,000 cubic ft/second or 89,869 gallons/second. At New Orleans, the average flow rate is 600,000 cubic feet per second.
  Feature Icon Background Information
  There are 7.489 gallons of water in a cubic foot. One cubic foot of water weighs 62.4 pounds. A 48 -foot semi-truck trailer is a 3,600 cu. ft. container.
  At Itasca, it would take 10 minutes for one semi-trailer of water to flow out of the lake into the Mississippi.
  At St. Anthony Falls, the equivalent of 3 semi-trailers full of water go over the falls every second. At New Orleans, the equivalent of 166 semi-trailers of water flow past Algiers Point each second.
5. Re:As always, it's a scale problem. by Anonymous Coward · 2011-05-05 06:27 · Score: 0
  
  Yep, according to the linked page, the flow at New Orleans is 600,000 cubic feet per second (which is 4,488,311.69 US gallons according to Google).
  According to the calculations above, that's about 34,525MW if you could utilize the entire flow at that point. Not quite an order of magnitude more than Fukishima, but pretty close.
6. Re:As always, it's a scale problem. by holmstar · 2011-05-05 07:16 · Score: 2
  
  For a large-ish 2000MW plant, it would need 260000 gallons per second of fresh water. At the MOUTH on the Mississippi (where it meets the ocean), that would make up about 5.8% of the over all flow of the river. Not as big of a deal as you are suggesting
  
  If you diverted a quarter of the flow (probably possible, if not practical), you could supply a plant that provides over 8000MW. It would certainly be a big facility, but that's also a lot of electricity.
7. Re:As always, it's a scale problem. by Anonymous Coward · 2011-05-05 08:21 · Score: 0
  
  ... and wouldn't it be easier to just put a turbine in all that flowing water?
8. Re:As always, it's a scale problem. by gurudyne · 2011-05-05 09:00 · Score: 1
  
  Mmmm! Catfish sushi!
  (And, considering the water quality, it comes with e coli sauce.)
  
  --
  Hey, Mom! Is it beer, yet?
9. Re:As always, it's a scale problem. by Anonymous Coward · 2011-05-05 09:45 · Score: 0
  
  I believe what he's saying -- and please tell me if I'm wrong -- is that there really isn't enough freshwater flowing to make a substantial dent in the energy economy. It's a technology with a relatively limited utility, but enormous cost of developing. How many places can you build this thing?
10. Re:As always, it's a scale problem. by Anonymous Coward · 2011-05-05 14:38 · Score: 0
  
  Fukishima is around 4900MW.
  Fukushima's power output is zero, and likely to remain that way.
  FTFY
11. Re:As always, it's a scale problem. by ResidentSourcerer · 2011-05-06 01:34 · Score: 1
  
  To me this concept is exciting: It's a way of collecting AND STORING solar energy.
  Using the Mississippi at Itasca is a bit disingenuous. That's fairly close to the headwaters, where it is still small.
  At the bottom end, the Mississippi has an annual discharge of about 500 km3/year, which corresponds to about 4.2 million gal/s
  So that means you can't put one everywhere. Hydro power is a scale problem too. In hot climates this may be a good way to store power:
  Sunlight evaporates ponds. Generate power as needed from sea water + brine pond.
  There are a fair number of big rivers that could be tapped.
  In addition the Dead Sea, and parts of the Sahara are below sea level.
  Death Valley is probably too picturesque, but the Salton Sea may be suitable. If you want to do this on a large scale dike off the Sea of Cortez (between the Baha peninsula and the mainland Mexican coast.
  The much larger gradient between ocean water and the Dead Sea means more watts per gallon of flow.
  If done cleverly, the energy from mixing a few gallons of ocean water with a few gallons of brine may be sufficient to desalinate a few gallons of ocean water -- in part of the world where fresh water is scarce.
  Looking at it another way if 13000 gal/s = 100 MW you're getting about 7500 J/gallon.
  A gallon is about 8 lbs. Call it 40 newtons. So the energy is roughly equivalent to a lift of 200 m.
  Now if the energy to be gained is proportional to the amount of dissolved salt, then for concentrated brine (about 30%) there should be about 75000 J/gallon.
  Couple this with the idea of tower evaporators:
  Desert climate: Build a tall tower in the middle of a large shallow pond. In the day, the pond gets warm, evaporates. Pump warm water to the top of the tower. Drop as a mist. Evaporative cooling makes the air heavier. Choose water droplet size so that about 3/4 of the water evaporates. Now you have cold wet air coming out of the base of the tower. At night this can create a heavy dew -- lots of desert plants can survive on dew.
  The wind from the outrushing air may be enough to run the pumps. The brine + seawater runs the salt water battery system.
  Salt can either be used as a feed stock for various chemical processes or stacked out of the way, like surplus sufur is now.
  
  --
  Third Career: Tree Farmer Second Career: Computer Geek First Career: Teacher, Outdoor Instructor, Photographer.
12. Re:As always, it's a scale problem. by tacokill · 2011-05-06 07:52 · Score: 1
  
  No, it's not a lot of electricity. That is, literally, a drop in the bucket compared to what we actually need, use, and presently produce. That's my point.
13. Re:As always, it's a scale problem. by uninformedLuddite · 2011-05-06 13:52 · Score: 1
  
  It's a technology with a relatively limited utility, but enormous cost of developing. How many places can you build this thing?
  Just about anywhere you can find technologically illiterate taxpayers
  
  --
  The new right fascists are bilingual. They speak English and Bullshit.
14. Re:As always, it's a scale problem. by holmstar · 2011-05-12 03:27 · Score: 1
  
  For one electrical plant 8000MW is a lot of electricity. It wouldn't be the largest in the world, but it would be roughly the sixth largest. And all of the larger ones are hydro.
Over time ... by applematt84 · 2011-05-05 04:07 · Score: 1

Over time, wouldn't mixing fresh water with salt water throw off the balance and eventually kill marine life? I'm not a marine biologist, but this sounds like a bad and an idea that's not been well thought out.
1. Re:Over time ... by gurudyne · 2011-05-05 04:55 · Score: 1
  
  Not if you do it at the outlet of a river to the sea, where the mixing has been happening for billions of years. I think life in that area has adapted by now.
  
  --
  Hey, Mom! Is it beer, yet?
Re:Wouldn't this "leach" material from the electro by ArsenneLupin · 2011-05-05 04:26 · Score: 1

Isn't the chlorine the material that is exchanged? Not the actual electrodes?
Indeed, you are right. Both electrodes absorb salt ions: chlorine is taken up by the silver electrode and sodium is taken up by the manganese dioxide electrode.
Hmmm, impressive how the manganese dioxide can stabilize the sodium, hehe...
vice verca by JadedIdealist · 2011-05-05 05:05 · Score: 1

Like reverse osmosis - in reverse ;)
TOO LATE by Anonymous Coward · 2011-05-05 16:23 · Score: 0

I remember as a kid I had a Captain Planet Water Wristwatch. It used TAP water to make electricity.
NOT REALLY NEW