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A Clever New Approach To Desalination

kdawson posted more than 4 years ago | from the pass-the-salt dept.

Earth 128

jbeaupre writes "The Economist reports on progress by a company called Saltworks on using saline gradients to do the heavy lifting of desalination. In essence, Saltworks uses solar energy or waste heat to concentrate sea water. They then use the ionic gradient between the concentrated brine and two sea-water streams to pull ions from from a 3rd sea-water stream. It appears to work with entropy by trading the reduced entropy of the desalinated water against the increased entropy of 'mixing' the brine and the other sea-water streams. The article only discusses Na and Cl, but even just removing these ions is a step in the right direction."

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It's old actually (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#29936507)

Just have her swallow.

Entropy? (0)

Anonymous Coward | more than 4 years ago | (#29936527)

If they need entropy why don't they just use /dev/random rather than wasting valuable solar energy?

Real Question - Please Answer (-1, Flamebait)

Anonymous Coward | more than 4 years ago | (#29936771)

Does the word "nigger" actually personally offend you? Or do you avoid it and frown on its use because you feel like you're supposed to? Real question, and maybe as an AC you can give a truly honest answer.

Re:Real Question - Please Answer (0)

Anonymous Coward | more than 4 years ago | (#29936917)

Does the word "nigger" actually personally offend you? Or do you avoid it and frown on its use because you feel like you're supposed to? Real question, and maybe as an AC you can give a truly honest answer.

The word doesn't offend me. I avoid it because I realize that others may be offended by it, and I do not understand the complex history of its word. Besides, there are plenty of other ways to refer to other human beings besides the color of their skin. Consider their first and last name, for instance.

Re:Real Question - Please Answer (1, Insightful)

Anonymous Coward | more than 4 years ago | (#29938155)

Does the word "nigger" actually personally offend you? Or do you avoid it and frown on its use because you feel like you're supposed to? Real question, and maybe as an AC you can give a truly honest answer.

The word doesn't offend me. I avoid it because I realize that others may be offended by it, and I do not understand the complex history of its word. Besides, there are plenty of other ways to refer to other human beings besides the color of their skin. Consider their first and last name, for instance.

It's also,important to remember that it does not have to denote a race or skin color. I tend to evaluate people based on their actions, and I have learned that the epithet could be applied to many of the people that post flamebait as AC. You are what you do, this is your hood, and your question is just some more mostly worthless graffiti. I say mostly worthless because it DOES show YOUR true color, no matter your race.

Re:Real Question - Please Answer (0)

Anonymous Coward | more than 4 years ago | (#29937025)

It does not, because thankfully I'm not one.

Re:Real Question - Please Answer (0)

Anonymous Coward | more than 4 years ago | (#29937203)

Who cares?

Oh no! (0, Funny)

Anonymous Coward | more than 4 years ago | (#29936545)

This could create greater access to fresh water. That could reduce the likelihood of a water based we're-all-going-to-die situation. What if we have to find some other end of the world catastrophe to whine about?

Making Dew (2, Interesting)

lyinhart (1352173) | more than 4 years ago | (#29936563)

Thinking about desalination makes me remember that episode of "The Voyage the Mimi [wikipedia.org] " in which they used the process to make drinking water:

http://video.google.com/videoplay?docid=-524069894840499801# [google.com] (A/V's not synced)

Re:Making Dew (1)

nomadic (141991) | more than 4 years ago | (#29936741)

Best. Show. Ever. And the Apple II computer games based on it they let us play were pretty cool too.

simpler way to get fresh water (0)

goombah99 (560566) | more than 4 years ago | (#29936881)

1) use the sun to create sea salt.
2) sell it
3) buy fresh water.

Re:Making Dew (1)

Abcd1234 (188840) | more than 4 years ago | (#29936895)

Thank you thank you thank you! Christ, I spent *years* trying to remember the name of that damn show!

Re:Making Dew (0)

Anonymous Coward | more than 4 years ago | (#29938177)

Speaking of remembering things. Did nyone ever have a tandy color computer 3? There was this game I had for it where it was like an rpg. You had one small window for the map. You moved around a village and collected stuff. MAybe you were trying to find some kind of legendary gem or something. I remember there was this one area that was a maze that I could never figure out. I played the game so long I was fighting arch-demons but I was still in the same village. I think when you foguth a monster it was like a MUD where there was a part of the ui where you typed in commands and it would tell you if you hit i, or it hit you.

Does anyone remember thename of that game? I have searched in vain.

Re:Making Dew (0)

Anonymous Coward | more than 4 years ago | (#29939013)

Yeah, now we can all go back and remember Ben Affleck before he was a ubiquitous asshole.

Re:Making Dew (1)

fotbr (855184) | more than 4 years ago | (#29939091)

Likewise! Of course, it'll take another 10 years for me to even think of it again, by which time I'll have forgotten. Again.

Re:Making Dew (1)

no1nose (993082) | more than 4 years ago | (#29937275)

Wow! Thank you for taking me back to 6th grade!! I loved that series!

Re:Making Dew (1)

s2theg (1185203) | more than 4 years ago | (#29938453)

NO! NEVER CROSS THE STREAMS!

Maybe (1, Interesting)

clang_jangle (975789) | more than 4 years ago | (#29936583)

From TFA:

The process begins by spraying seawater into a shallow, black-bottomed pond, where it absorbs heat from the atmosphere. The resulting evaporation increases the concentration of salt in the water from its natural level of 3.5% to as much as 20%. Low-pressure pumps are then used to pipe this concentrated seawater, along with three other streams of untreated seawater, into the desalting unit. As the diagram explains, what Mr Sparrow and Mr Zoshi create by doing this is a type of electrical circuit. Instead of electrons carrying the current, though, it is carried by electrically charged atoms called ions.

Except for that last absurdly inaccurate statement (made me chuckle), this sounds really good. Not the fastest way to desalinate, so it would take an awful lot of these to meet demand (or one really gigantic one), but still this could be at least a partial solution.

Re:Maybe (0)

Anonymous Coward | more than 4 years ago | (#29936617)

" Instead of electrons carrying the current, though, it is carried by electrically charged atoms called ions."

Except for that last absurdly inaccurate statement (made me chuckle),

I don't get it

Re:Maybe (0, Troll)

clang_jangle (975789) | more than 4 years ago | (#29936639)

I don't get it.

The ions are not a substitute for electrons, they're the source. There is no electricity without electrons. :)

Re:Maybe (0)

Anonymous Coward | more than 4 years ago | (#29936727)

More precisely ions are a *carrier* of charge (which can be an electron, or the lack of an electron), and the quote said "carry", so there's nothing wrong with it.

Re:Maybe (1, Interesting)

clang_jangle (975789) | more than 4 years ago | (#29936775)

To say, " Instead of electrons carrying the current, though, it is carried by electrically charged atoms called ions" is inaccurate. The electron stream (which we call electricity) is still an electron stream. It would have been more accurate had they said, " Instead of using wires or cables to carry the current, though, it is carried by electrically charged atoms called ions."

Re:Maybe (0)

Anonymous Coward | more than 4 years ago | (#29936903)

Nah. Current is the flow of charge. An electron is a little wagon containing a charge. If you have a fixed wire with wagons rolling in it each carrying a charge, the charge is carried by the wagons, not the wire.

Re:Maybe (0)

Anonymous Coward | more than 4 years ago | (#29936965)

Even if you wish to frame it that way then saying the charge is carried by ions *instead* of electrons is wildly inaccurate, so I think GP's point stands. Still, "+1 Almost A Car Analogy".

Re:Maybe (4, Insightful)

AdamHaun (43173) | more than 4 years ago | (#29936993)

No, it's not inaccurate, unless you're claiming that protons don't have a charge. The ions here are nothing like wires. In a wire, the atoms (nuclei and nonconductive electrons) are fixed in position while the conduction band electrons are free to move from atom to atom. But in this desalinization process, the nuclei themselves actually move -- that's what makes it desalinization. The sodium and chlorine ions are true charge carriers. Ion conduction is not uncommon. Here's some more info on that:

http://amasci.com/amateur/elecdir.html [amasci.com]

Re:Maybe (4, Informative)

klaun (236494) | more than 4 years ago | (#29936769)

The ions are not a substitute for electrons, they're the source. There is no electricity without electrons. :)

Electricity is the flow of charge, not electrons.

If your statement was accurate, your computer would not work as it depends upon semiconductors which function in part based on the flow of positively charged holes in the electron structure of the material. (see p-n junctions, etc.) The Hall effect can be used to verify the charge of the moving carrier within a current. It can be either positive or negative.

Note that this desalinization mechanism works very similarly to a fuel-cell which also involves ion flow as part of an electric circuit.

Re:Maybe (0)

Anonymous Coward | more than 4 years ago | (#29936821)

-1 Pedantic. Go create current without electrons, publish, then say the satement was "inaccurate".

Re:Maybe (2, Informative)

644bd346996 (1012333) | more than 4 years ago | (#29937171)

A stream of alpha particles would have a well-defined current, despite the lack of electrons.

Re:Maybe (1)

maxfresh (1435479) | more than 4 years ago | (#29936891)

For every hole moving in one direction within the semiconductor substrate, is there not a corresponding electron moving in the opposite direction?

Re:Maybe (1)

Hognoxious (631665) | more than 4 years ago | (#29937067)

Be that as it may, atoms are not ions, which is what the attempt at an article states.

Re:Maybe (2, Informative)

gtbritishskull (1435843) | more than 4 years ago | (#29937165)

You do not know what you are talking about. An ion is an atom (or group of atoms) that have more protons than electrons. Maybe you should spend a few hours on wikipedia boning up on your basic chemistry.

Re:Maybe (1)

WGFCrafty (1062506) | more than 4 years ago | (#29937395)

You do not know what you are talking about. An ion is an atom (or group of atoms) that have more protons than electrons. Maybe you should spend a few hours on wikipedia boning up on your basic chemistry.

Maybe you should spend some more time on wikipedia.

There DO NOT need to be more protons than electrons, they just need to be a non-equal quantity so that there is a net charge, making it a negatively OR positively charged atom/molecule.

Now, what you were saying would be correct if you were referring to cations specifically, which DO have more protons than electrons.

Re:Maybe (5, Informative)

maxfresh (1435479) | more than 4 years ago | (#29937231)

Be that as it may, atoms are not ions, which is what the attempt at an article states.

The article doesn't state that atoms are ions. Rather, it states that ions are electrically charged atoms, which is totally correct. Here is the exact quote, in context:

As the diagram explains, what Mr Sparrow and Mr Zoshi create by doing this is a type of electrical circuit. Instead of electrons carrying the current, though, it is carried by electrically charged atoms called ions.

Salt is made of two ions: positively charged sodium and negatively charged chloride. These flow in opposite directions around the circuit. Each of the four streams of water is connected to two neighbours by what are known as ion bridges. These are pathways made of polystyrene that has been treated so it will allow the passage of only one sort of ion--either sodium or chloride. Sodium and chloride ions pass out of the concentrated solution to the neighbouring weak ones by diffusion though these bridges (any chemical will diffuse from a high to a low concentration in this way).

I don't find any incorrect statement in the above quote regarding ions.

Re:Maybe (0)

Anonymous Coward | more than 4 years ago | (#29936751)

I don't get it

Don't worry. I don't get it either.
:)

Re:Maybe (1)

jeffstar (134407) | more than 4 years ago | (#29936721)

what if they collected the fresh water vapour that is evaporating off the salt water as well?

TFA says they make fresh water by heating salt water with electricity so why not just heat it mostly with the sun and then a bit of electricity.

TFA is a bit light on details: why do Na+ ions go to one stream and CL- to the other? Have they got membranes that are impervious to CL- and NA+?

Re:Maybe (5, Informative)

Timothy Brownawell (627747) | more than 4 years ago | (#29936743)

what if they collected the fresh water vapour that is evaporating off the salt water as well?

I'm guessing this would require active refrigeration unless they're in a colder climate?

TFA is a bit light on details: why do Na+ ions go to one stream and CL- to the other? Have they got membranes that are impervious to CL- and NA+?

Yes. From TFA:

Each of the four streams of water is connected to two neighbours by what are known as ion bridges. These are pathways made of polystyrene that has been treated so it will allow the passage of only one sort of ion—either sodium or chloride.

Re:Maybe (1)

TubeSteak (669689) | more than 4 years ago | (#29936931)

I'm guessing this would require active refrigeration unless they're in a colder climate?

You just put a roof over it and collect whatever condenses.
But unless you have a lot of surface area, the water you collect will be negligble in comparison to the main distillation process.

Re:Maybe (0)

NotBornYesterday (1093817) | more than 4 years ago | (#29937057)

Wouldn't that roof interfere with the sun striking the black-bottomed pool?

Re:Maybe (2, Funny)

Neoprofin (871029) | more than 4 years ago | (#29937143)

It doesn't in my terrarium.

Re:Maybe (4, Funny)

gandhi_2 (1108023) | more than 4 years ago | (#29937367)

True. Too bad greenhouses are impossible.

Re:Maybe (2, Funny)

dontmakemethink (1186169) | more than 4 years ago | (#29938163)

(to the music of Queen) - Black-bottomed pool you make the salty ions get found!

Sorry, couldn't resist

Re:Maybe (1, Troll)

Rei (128717) | more than 4 years ago | (#29937123)

Yeah, you "just" put a roof over it. As though that wouldn't 10x the construction and maintenance costs of the evaporation ponds. :P

Re:Maybe (1)

Hognoxious (631665) | more than 4 years ago | (#29937095)

what if they collected the fresh water vapour that is evaporating off the salt water as well?

I'm guessing this would require active refrigeration unless they're in a colder climate?

If it's on Earth, then it is a colder climate. Colder than 100 degrees centigrade. Or as you probably call it, 212 degrees-F.

Re:Maybe (1)

Culture20 (968837) | more than 4 years ago | (#29937161)

what if they collected the fresh water vapour that is evaporating off the salt water as well?

I'm guessing this would require active refrigeration unless they're in a colder climate?

If it's on Earth, then it is a colder climate. Colder than 100 degrees centigrade. Or as you probably call it, 212 degrees-F.

Exactly. Just get a really long Aluminum pipe for the "waste steam", slightly angle it down, and you've got a water condenser. Run the "waste" pipe next to the input water pipe, and you've got increased efficiency on both heating and cooling.

Re:Maybe (1)

Timothy Brownawell (627747) | more than 4 years ago | (#29937219)

what if they collected the fresh water vapour that is evaporating off the salt water as well?

I'm guessing this would require active refrigeration unless they're in a colder climate?

If it's on Earth, then it is a colder climate. Colder than 100 degrees centigrade. Or as you probably call it, 212 degrees-F.

Very funny, please go read up on "vapor pressure".

All that's needed to get some condensation is a surface that's colder than the pool, and in the same enclosed area. The trouble is, the rate of condensation and evaporation depends on the temperature differential between the condenser and the pool. So if your ambient temperature is 90 F and your pool is heated to 100 F you won't see very much evaporation compared to if you just exhaust your waste humidity into the (presumably comparatively dry) environment.

Re:Maybe (1)

Avin22 (1438931) | more than 4 years ago | (#29937339)

"what if they collected the fresh water vapour that is evaporating off the salt water as well?" I was thinking that might actually be a good idea, with a slight tweak. Instead of collecting the evaporated water as a byproduct of this process, why not combine this with the process of reverse osmosis. One of the major difficulties with reverse osmosis (in addition to the energy requirement) is that it produces a highly concentrated brine that must be disposed of. Instead of dumping it back in the ocean, why not first use it to fuel this type of osmosis as well? That way, the process is not limited by the amount of heat in the environment because it does not need to evaporate any new source of water.

Re:Maybe (1)

biryokumaru (822262) | more than 4 years ago | (#29938671)

Unfortunately, RO systems still require high pressures to work. That defeats the benefit of this new system, wherein no high pressure system (thereby no steel piping, no expensive pumps) is required.

Re:Maybe (1)

PrinceAshitaka (562972) | more than 4 years ago | (#29936779)

Because these 4 "streams" conatin a medium that only allows positivly or negativley charged particle to travel through it depending on what is required.

Re:Maybe (1)

Langolier (470727) | more than 4 years ago | (#29939039)

And what if they let the water vapour, that is lighter than air, rise, and cool off by rising, to the point where it would condense again?
And if the rising force of the water vapour was used to drive some fans or turbines?

Or they could just release enough water vapour, letting it rise, so that there would be more precipitation downwind of the site. All of these would
generate power, and more fresh water, as well.

Re:Maybe (1)

countertrolling (1585477) | more than 4 years ago | (#29939141)

what if they collected the fresh water vapour that is evaporating off the salt water as well?

Or better yet, collect the billions of gallons of condensate that falls out of the sky every day. Then you don't have to worry about all those silly ions, electrons and membranes.

Re:Maybe (4, Funny)

samkass (174571) | more than 4 years ago | (#29936753)

Dr. Flammond: "A year ago, I was close to perfecting the first magnetic desalinization process. So revolutionary, it was capable of removing the salt from over a million gallons of sea water a day! Do you realise what that could mean to the starving nations of the earth?"

Nick Rivers: "My God, they'd have enough salt to last forever!"

Re:Maybe (1)

roguetrick (1147853) | more than 4 years ago | (#29938201)

Current is by definition the flow of charge. In the case of your muscles, there is an electrical current along the muscle cell membrane that is caused by a change in the amount of cations allowed into the cell.

Anyone else think... (0)

Anonymous Coward | more than 4 years ago | (#29936621)

anyone else think this looks suspiciously like: http://en.wikipedia.org/wiki/Perpetual_motion

Re:Anyone else think... (0)

buchner.johannes (1139593) | more than 4 years ago | (#29936651)

Exactly. They built a perpetuum mobile that requires less than 1 kWh.

Re:Anyone else think... (5, Informative)

bcmm (768152) | more than 4 years ago | (#29936739)

anyone else think this looks suspiciously like: http://en.wikipedia.org/wiki/Perpetual_motion [wikipedia.org]

Yeah, pretty much, for all practical purposes, but not quite, because sooner or later the fucking sun will in fact burn out.

You didn't need to read TFA. It's in the summary. Second sentence.

Saltworks uses solar energy or waste heat

Re:Anyone else think... (4, Funny)

Jah-Wren Ryel (80510) | more than 4 years ago | (#29936835)

Yeah, pretty much, for all practical purposes, but not quite, because sooner or later the fucking sun will in fact burn out.

Or get bought out by Oracle after giving away all its energy for Free.

Re:Anyone else think... (1)

Ironchew (1069966) | more than 4 years ago | (#29937251)

There ain't no such thing as a free Sun.
I feel like a single-celled organism subsisting on a decomposing lunch for only a few seconds.

Re:Anyone else think... (2, Interesting)

tehdaemon (753808) | more than 4 years ago | (#29936979)

An appropriate link: The Last Question [multivax.com]

T

Re:Anyone else think... (0)

Anonymous Coward | more than 4 years ago | (#29937647)

Yeah, pretty much, for all practical purposes, but not quite, because sooner or later the fucking sun will in fact burn out.

LOLLLL

Re:Anyone else think... (1)

queequeg1 (180099) | more than 4 years ago | (#29936791)

Not really. The article clearly indicates that heat input is required (i.e. it doesn't purport to be a system that produces more energy than is put into it). The beauty of this system is that this energy is obtained from a source we don't have to pay for (i.e., the sun).

Re:Anyone else think... (1)

Dunbal (464142) | more than 4 years ago | (#29937951)

(i.e. it doesn't purport to be a system that produces more energy than is put into it)

      "Perpetual motion" doesn't produce necessarily "more" energy than is put into it. It simply doesn't require energy at all apart from the initial "push". And that is, of course, absolute rubbish, thanks to friction, diminishing returns, and any other number of physical laws that favor entropy.

      I just don't understand how this project is meant to work. Maintaining those "concentration gradients" is going to take more energy than just sunlight. Yes you could vary the volumes of the "pools" (and thus the amount of evaporation) to help maintain your concentrations within a given range. However eventually you are going to have to flush the whole system and start again, since it will always tend towards equilibrium. And if you started with salt water, equilibrium is NOT fresh water.

      Human kidneys (something I know about as a doctor), for example, use salinity gradients to concentrate urine and also remove necessary salts - after all you don't want to be literally pissing all of your sodium, potassium and calcium away without SOME sort of control. However this control requires energy, in the form of ATP, and LOTS of it. This is one reason the kidneys are one of the most sensitive organs to oxygen deprivation, after the brain and the heart (but even heart muscle can take a beating - the problem there is more one of inadequate blood supply rather than oxygen demand) - even though the kidneys receive 20% of the body's blood flow. They NEED it to survive, because they consume tremendous amounts of oxygen to produce enough ATP to maintain all those gradients.

      Frankly I think the article is badly written - probably intentionally especially if the inventors "think they're on to something" - and I fail to understand how it works on a fundamental level. But kudos to them if they're right. I guess we'll find out how it really worked in a few years. Or not.

Re:Anyone else think... (1)

roguetrick (1147853) | more than 4 years ago | (#29938353)

Seems pretty simple to me. The ions flow down their concentration gradients creating opposite charges in streams that were once regular seawater, through some sort of bridge that only allows Cl ions into one stream and Na ions into the other stream. Then the seawater that needs to be desalinized is connected, the ions can't escape the charged streams due to their bridges, but the ions from the seawater to be desalinized travel to the charged streams. After that, you dump the charged streams and start over again. About the only thing I'm not sure on is the last part, as I imagine the ions would flow due to the charge and not be permitted to flow due to their concentration gradient due to the nature of the bridges?

Anyway, the first part certainly is simple enough to understand from a physiology perspective. Hell, thats how the action potential works. Create an imbalance using energy(ATP in the body, sunlight in this example) and then use semipermeable membranes to create a charge.

Re:Anyone else think... (2)

nedlohs (1335013) | more than 4 years ago | (#29936803)

Other than the fact that they are consuming not producing energy, yeah exactly like that...

Re:Anyone else think... (1)

CarpetShark (865376) | more than 4 years ago | (#29938205)

I was thinking, "In this house we obey the laws of thermodynamics!"

It's probably the wave of the future (pun intended (1)

Amester (1507943) | more than 4 years ago | (#29936663)

Desalinization is most likely the wave of the future, given the rise in sea levels and melting ice. We might as well put the extra water to good use, rather than just let our low-lying lands drown.

Re:It's probably the wave of the future (pun inten (2, Interesting)

Absolut187 (816431) | more than 4 years ago | (#29936909)

Agreed. We (homo sapiens) should get to work on massive desalination efforts and fill up some of the lakes that have been going dry for years. Like lake Mead [nytimes.com] , the sea of Galilee [encyclopedia.com] , etc.

Maybe if we fill up enough large lakes/seas with desalinated water we can make a small dent in sea level rise.

Some new manmade lakes in Africa wouldn't hurt either. They seem to be short on potable water all the time.

Re:It's probably the wave of the future (pun inten (2, Funny)

NotBornYesterday (1093817) | more than 4 years ago | (#29937083)

And we could freeze a bunch of it and ship it to the poles.

Why would the Poles want more ice? (2, Funny)

zooblethorpe (686757) | more than 4 years ago | (#29939227)

The winter in Poland is already plenty cold enough...

:-P

Cheers,

If by "clever new approach" you mean... (0)

Anonymous Coward | more than 4 years ago | (#29936681)

...what all flora has been doing forever.

I'll get modded off topic.... (0, Offtopic)

allaunjsilverfox2 (882195) | more than 4 years ago | (#29936691)

But it was kinda funny, right above the article title was a statement on how to filter firehose.

Vancouver saves the world? (3, Interesting)

Yergle143 (848772) | more than 4 years ago | (#29936747)

OK between this and the General Fusion guys http://www.generalfusion.com/ [generalfusion.com] Canada has got water and energy completely licked. http://www.saltworkstech.com/ [saltworkstech.com] OK actually I'm still trying to run the numbers on the both of them (and waiting for some peer reviewed publications.)

Re:Vancouver saves the world? (1)

pete-classic (75983) | more than 4 years ago | (#29936809)

If you have the first one, the second one becomes redundant. Loads of problems just go away if you have cheap, abundant, clean energy.

-Peter

General Confusion (1, Interesting)

epine (68316) | more than 4 years ago | (#29936997)

Thank you for that link to General Confusion. Made my day. Check out the freshman T-rex with his lava lamp and the sordid diatripe:

http://www.generalfusion.com/fossil_fuel_crisis.php [generalfusion.com]

The planet was covered with dense clouds and the atmosphere contained a high concentration of carbon dioxide, producing tropical conditions north of the 45th parallel. For example, many dinosaur fossils were excavated in Alberta, Canada. As the earth's crust cooled down, volcanic activity reduced.

Riddle of Burgess Shale's fossil-rich deposits solved [canada.com]

The site, close to the B.C.-Alberta border, is considered crucial to understanding the so-called Cambrian "explosion" of life - a time when the future Canadian land mass was drifting in tropical climes close to the Earth's equator.

In my historical atlas, the equator is considerably south of the 45th latitude. The dinosaur fossils in Alberta are equatorial in origin. But hey, if you can't get that right, no obstacle to solving the fusion problem. Like it's not a hard problem or anything. The typical Alberta fat cat oilman probably doesn't believe in plate tectonics to begin with. Just a bunch of mud we turn into money. Now they're all excited about version 2: just a bunch of water we turn into money.

BTW, the Royal Tyrrell Museum [tyrrellmuseum.com] in the Alberta badlands is pretty kick-ass if you're into bones.

Re:General Confusion (2)

Interoperable (1651953) | more than 4 years ago | (#29937447)

I'm fairly certain that the oil industry has a particularly good understanding of plate tectonics; the term "fossil fuels" isn't lost on them.

Re:General Confusion (1)

EL_mal0 (777947) | more than 4 years ago | (#29938231)

You're right that the equator is considerably south of the 45th parallel. However, you forget that continents move around, given enough time. So in the Cambrian North America (Laurentia) was near the equator - here's a map [scotese.com] . Fast forward 320 million years to when the dinosaurs began to rule the earth, and North America is approaching where it is today - here's another map. [scotese.com] Note how Alberta is approaching the 45th parallel, where it is found in your atlas.

You need to get yourself a different atlas if you're going to think about things that happen over geologic timescales.

You lost me at 'Desalination' ... (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#29936913)

Huh, what ?

ion bridges cost? Consumable? (3, Insightful)

140Mandak262Jamuna (970587) | more than 4 years ago | (#29936945)

The key piece of the work is an ion bridge. This has to permit the travel of one kind of ion but not the other, i.e. Na+ or Cl-. Looks like this material could be expensive. It might plug up need to be periodically replaced. How expensive these are? How non toxic these are? What is needed to manufacture them? These are the questions we need to ask.

Re:ion bridges cost? Consumable? (2, Insightful)

Vesvvi (1501135) | more than 4 years ago | (#29937121)

More important than the cost is the question of effectiveness.

In their diagram, they have this schematic in the critical location:

[Salt water]<----(+)----[Brine]----(-)----->[Salt water]

Chemically, that "equation" just doesn't balance without an input of energy.  It doesn't matter what kind of "ion bridges" they put into place between the brine and salt water reservoirs, or what the concentration of salt exists in the brine or salt water, it will require some energy to offset the entropy increase.

It's possible that they have some active system in place in the bridges, but it's going to take some kind of energy input which is missing from their explanation.

Re:ion bridges cost? Consumable? (2, Informative)

klaun (236494) | more than 4 years ago | (#29937211)

Chemically, that "equation" just doesn't balance without an input of energy.

The energy was input by the sun before the different solutions were brought together.

it will require some energy to offset the entropy increase

delta S > 0 for a closed system as a consequence of the second law of the thermodynamics. No need for additional energy. The entropy of a the concentrated solution is less than the entropy of the dilute solution, hence dilution happens spontaneously, much like osmosis.

Re:ion bridges cost? Consumable? (1)

140Mandak262Jamuna (970587) | more than 4 years ago | (#29937217)

The energy comes from the Sun. The concentrated brine has higher mobility ions. Even if ion bridge allows ions to move in both directions, the higher concentration on one side will send more ions down to lower concentration side purely by diffusion. At some point the concentrations should equal and the flow should stop but the low pressure pumps keep pumping out the water with altered concentrations and keep the ion gradient active all the time.

Re:ion bridges cost? Consumable? (1)

John Hasler (414242) | more than 4 years ago | (#29937235)

The brine is created from a portion of the sea water. They use the sun to heat it and evaporate some of the H2O. This is the primary energy input.

Re:ion bridges cost? Consumable? (3, Informative)

whit3 (318913) | more than 4 years ago | (#29937255)

More important than the cost is the question of effectiveness.

In their diagram, they have this schematic in the critical location:

[Salt water]<----(+)----[Brine]----(-)----->[Salt water]

Chemically, that "equation" just doesn't balance without an input of energy.

The article DOES explain this, the salt imbalance makes
a kind of battery.

It's brilliant! Solar energy concentrates a brine, which
then (just as dissimilar metals make a thermocouple)
causes current and builds an electric potential
when connected via a membrane (impermeable
except to Na+ ions) to a less-concentrated brine.

So, the difference in concentration of ions between two
channels results in a diffusion from more-concentrated to
less-concentrated, OF A CHARGED ION. That means
electric current flows, until the charge buildup raises
the electric potential enough to stop the diffusion.

The solar input concentrates the brine, the resulting
(small) voltage then is electrically applied to the to-be-desalinated
channel, and (in the absence of a concentration difference)
the electric field causes the ions to leave the
to-be-desalinated stream.

Thus, it's a solar-concentration-of-salt that makes
the desalination occur. The electricity caused by the
diffusion is active ALL NIGHT until the concentration
of salt goes down, so the concentrated brine is
an effective load-leveling device for the whole plant.

The 'electric input' part of the process is entirely for
pumping the brines around, so it can be a small fraction
of the brute-force desalination energy requirement.
Heck, you could use wave or wind power for that.

Solar collectors for this kind of gizmo are just open-air
trays of brine. Can't get any more cost-effective than
THAT.

Re:ion bridges cost? Consumable? (4, Informative)

Rich0 (548339) | more than 4 years ago | (#29937271)

You missed the other side of the reaction. It is charge neutral because the +/- charges in the two side pools are then balanced with -/+ charges from the water to be desalinated.

The charges flow apart in the first place because the central pool is highly concentrated - so it contains far more + and - charges than anything else in the system.

This kind of approach would never yield completely drinkable water, but that isn't the point. The goal is to get rid of a lot of the ion load before using more expensive processes to get rid of the rest.

Desalination is a marvel of process optimization. Multiple stages of purification are used - each one being more expensive than the last but more effective. The early steps get rid of a huge mass of dissolved matter for dirt cheap, so even if their product isn't drinkable it GREATLY reduced the cost of the later stages.

If you don't care about cost then desalination is trivially easy. Just run any kind of water you like through a H+ exchange resin followed by an OH- exchange resin, and then run it trough activated charcoal. The resulting water will be as clean as clean can be and the system would be remarkably simple. The catch is that those resins cost a small fortune to make, and if you run seawater into them then they're probably going to last all of 5 minutes. It might be a good approach for a camper to use to obtain water (the resin is a lot lighter than the amount of water that it could clean), but it is not a cost-effective method overall. Also - the purity it would achieve would be massive overkill. This is drinking water - we're not manufacturing CPUs.

Re:ion bridges cost? Consumable? (0)

Anonymous Coward | more than 4 years ago | (#29938829)

Water does not need to be salt-free to be sustainably drinkable, it just needs to be less salty than the most concetrated urine that humans can produce.

Re:ion bridges cost? Consumable? (3, Informative)

Timothy Brownawell (627747) | more than 4 years ago | (#29937305)

[Salt water]<----(+)----[Brine]----(-)----->[Salt water]

Chemically, that "equation" just doesn't balance without an input of energy. It doesn't matter what kind of "ion bridges" they put into place between the brine and salt water reservoirs, or what the concentration of salt exists in the brine or salt water, it will require some energy to offset the entropy increase.

This is exactly backwards; energy input is required in order to decrease entropy of (part of) a system. Entropy increases come for free. Consider if you fill one half of a fish tank with fresh water and the other half with brine, do you get a fish tank full of somewhat salty water or do the fresh and salt water separate out?

Re:ion bridges cost? Consumable? (5, Informative)

MoellerPlesset2 (1419023) | more than 4 years ago | (#29937299)

The key piece of the work is an ion bridge.

No, the key piece of work is the idea. Ion bridges have been around forever.

This has to permit the travel of one kind of ion but not the other, i.e. Na+ or Cl-. Looks like this material could be expensive.

So you use, for instance, a polymer electrolyte (ionomer) with negatively charged side-chains for one bridge and a polymer with positively charged side-chains on the other. Only the counterions are mobile. The article says they're using modified polystyrene. This is not new, or terribly expensive. Similar things are already being used in industrial desalination technology for ion exchange columns.

It might plug up need to be periodically replaced.

Plug up with what? You naturally would have a mechanical filter to keep the crap out. It's not a major problem.

How expensive these are? How non toxic these are? What is needed to manufacture them? These are the questions we need to ask.

No, they're the questions asked by someone who doesn't know s--t about chemistry/chemical engineering. I happen to have a degree in the subject, but damnit, I learned about (used, even) polymer ion exchange columns in high school. If you want answers to your questions, go get Coulson & Richardson or some other chemical engineering textbook, and find the relevant section.
This technology is certainly very clever, but it does not make use of any new technology. The only question I think is worth asking here is whether or not it turns out to be more efficient or not.

Re:ion bridges cost? Consumable? (0)

lawpoop (604919) | more than 4 years ago | (#29937587)

The only question I think is worth asking here is whether or not it turns out to be more efficient or not.

I detect a little unnecessary redundancy there.

Re:ion bridges cost? Consumable? (4, Insightful)

AcidPenguin9873 (911493) | more than 4 years ago | (#29937705)

Not everyone reading Slashdot has a degree in chemistry or chemical engineering. I appreciated OP's questions since I had the same ones. I appreciate your answers but not the attitude that I had to endure when reading your post.

Plug up with what? You naturally would have a mechanical filter to keep the crap out. It's not a major problem.

You answered the dumb question but failed to answer the smarter one. Does the ion bridge ever somehow lose its effectiveness after a good amount of use? If it does, it will need to be replaced. How often does this happen? How much water can one of them desalinate before needing replacement? If it never needs replacement because of *use* (not mechanical crap getting in the way), then that's great, but I don't know the answer. Again, I do not have a degree in any of this stuff, so please enlighten me.

Re:ion bridges cost? Consumable? (5, Insightful)

nutshell42 (557890) | more than 4 years ago | (#29938051)

Not everyone reading Slashdot has a degree in chemistry or chemical engineering. I appreciated OP's questions since I had the same ones. I appreciate your answers but not the attitude that I had to endure when reading your post.

The attitude of the GP was the problem. "These are the questions we need to ask", as if they were non-obvious and revolutionary. Whenever there is a post about an invention on /. the easiest way to get "+5 (Group-Wank)" is to write that it will never work because the inventors overlooked an issue a drunk chimpanzee could come up with. Then a thread ensues where everyone congratulates themselves on saving the world yet again.

You are right, the GP's questions were interesting and should have been answered in the article (which is for laypersons) and because they weren't it's good that someone answered them here on /.

The problem is that the GP posed the question in a way that implied he knew what he was talking about and was making a statement about the invention, instead of admitting that he had no idea and was asking for clarification. jm2c

Sounds Like Forward Osmosis (0)

Anonymous Coward | more than 4 years ago | (#29937029)

Sounds like Forward Osmosis.

This it by no means a new technology or method.

Economist, not physicist (0)

Anonymous Coward | more than 4 years ago | (#29937071)

"The process begins by spraying seawater into a shallow, black-bottomed pond, where it absorbs heat from the atmosphere." ...
"All the rest of the energy has come free, via the air, from the sun."

I don't think solar radiation works the way The Economist thinks it does.
"The air" is cooling it off, not heating it. For that, you need something like a black-bottomed pond to absorb heat from solar radiation..

Maxwell's Demon (1)

andrewagill (700624) | more than 4 years ago | (#29937153)

From the way they describe it, it sounds a lot like Maxwell's Demon. Since there is energy going into the system, however, it's clearly not that.

Sounds a lot like forward osmosis (-1, Troll)

Anonymous Coward | more than 4 years ago | (#29937229)

How is this different than forward osmosis?

Re:Sounds a lot like forward osmosis (0)

Anonymous Coward | more than 4 years ago | (#29937383)

Did you know conventional desal plants produce lots of concentrated brine? If they could stripe the ionic difference out of this wase product, they would.

Reverse osmosis has a special filter.
OK here we have something called a 'Bridge' - same thing.
Forward / Reverse - depends which side - blowing or sucking.

You can flow water over such filters, BUT miserable output - you need pressure and emergy - lots of it to get water.

I think you can make a salt/brine battery from the ponds - but back of envelope calculations would reveal minimal energy contribution at end of day.

   

Reverse osmosis? (1, Interesting)

macraig (621737) | more than 4 years ago | (#29937597)

Isn't this a large-scale demonstration of the same principle used in home reverse-osmosis systems? It sure sounds familiar.

Re:Reverse osmosis? (4, Insightful)

stevelinton (4044) | more than 4 years ago | (#29938041)

No. It does look a bit similar but it isn't. In reverse osmosis the water has to pass through the membrane, driven by high pressure pumps, leaving its impurities behind.

In this version the impurities pass through the membrane (two separate membranes in fact) driven by an electrical current. Cleverly, the electrical current itself is generated by the salt passing through other membranes out of the highly concentrated brine that you made in your solar ponds.

One thing I've been wondering about for a while... (1)

Entropius (188861) | more than 4 years ago | (#29937963)

... is if it would be possible to combine solar-thermal power generation with desalination.

Build Fresnel-lens solar concentrators and stick them near a source of seawater. Boil the water using the sunlight, and use it as the working fluid in an ordinary steam-turbine-type power generator. But instead of recycling the same water once the steam recondenses, realize that you've just made a giant distiller: drink the water and use "new" seawater.

Re:One thing I've been wondering about for a while (0)

Anonymous Coward | more than 4 years ago | (#29938867)

Too bad salt water has a higher boiling point... it's easier to use a closed loop with pure water.

But what happens to the waste steam from the brine (0, Redundant)

upuv (1201447) | more than 4 years ago | (#29938067)

So I read the thing.

The process concentrates sea water to brine by an evaporation method. So why waste this low grade stream it is still has high in moisture content. There is already a condenser in this system. I'm thinking this can somehow boost output of clean water.

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