
Cheaper, cleverer desalination - 10ren
http://www.economist.com/sciencetechnology/displayStory.cfm?story_id=14743791
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stcredzero
What little energy is needed for pumping could also be supplied in-situ from
solar power. What about solar thermal driving turbines or steam engines? This
has the disadvantage of requiring high-pressure pipes. Solar Stirling?

An even better idea: if possible, use tides to fill the normal-conentration
seawater tank at a higher elevation, and let water flow naturally downstream.
Use the same tidal basin to generate the process electricity. This would
require a lot more infrastructure investment up-front, but that would pay off
in the form of much lower expenses for inputs afterwards.

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kbob
Or they could hire a boy to carry water with a bucket.

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stcredzero
I'd rather the community/polity got a grant so that boy could be engaged in an
activity with greater economic leverage. Or better still, be in school.

Such infrastructure would be in the "hand-up, not hand-out" category to me.
Also, the availability of fresh water on industrial scales would be an
economic enabler in itself.

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ajju
It doesn't have to be a boy. There are many poor communities around the world
where fully grown men would be thankful for any job.

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RK
I'll wait for the evidence that this actually works (and with efficiency
relative to the other schemes).

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apalmblad
I remember when they won a province wide business plan contest in Vancouver,
BC, and it was noted that a key reason they won (the 100k prize) was that they
had an engineering review indicating their process was feasible.

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rfreytag
How long before the ion bridges were clogged with biofilms, sediment, and
other detritus normally present in sea water?

Ion bridge replacement is another energy input.

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ggchappell
Very cool idea.

I'm reminded of the setup at Chena Hot Springs Resort (east of Fairbanks,
Alaska), where the temperature difference between a hot spring and a normal
stream, is used to run an air conditioner that keeps the interior of an "ice
museum" frozen year-round. It's a very different process, of course, but it
seems to me to involve similar thinking.

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noonespecial
It's kind of like dialysis, but for seawater. Sweet.

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leecho0
Great idea! Instead of trying to fight osmosis, use it. It's one of those "why
didn't I think of that" inventions.

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jorgem
Can the left over streams be mixed and reused? Since they will have higher
salinity and used as a new input?

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JoeAltmaier
The "cleaner" streams are heavily charged with ions - the high-sodium stream
with chlorine, the high-chlorine with sodium. It would probably take more
energy to charge them higher than using "neutral" seawater.

