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UK researchers create graphene-based sieve that can remove salt from seawater

bbc.com

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Re: UK researchers create graphene-based sieve that can remove salt from seawater

#111

Post by Nomentatus »

sp332 wrote: post #100

Is there a reason this wouldn't be subject to the same physics that requires a lot of energy to desalinate water by other means? Thermodynamics puts a limit on how efficiently you can reduce entropy like that.

I wouldn't say "a lot" in economic terms: "The theoretical absolute minimum amount of energy required by natural osmosis to desalinate average seawater is approximately 1 kilowatt-hour per cubic meter (kwh/m3) of water produced, or 3.8 kilowatt-hours per thousand gallons (kwh/kgal)." https://www.amtaorg.com/wp-content/uploads/7_MembraneDesalin...

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#112

Post by dredmorbius »

jessriedel wrote: post #52
throwaway91111 wrote: post #38

Earlier quoted context omitted.

Also, waste is a major problem, environmentally.

Are you talking about the brine? This is trivial if you just put a pipe a few hundred yards out to sea. The concentration is diluted extremely quickly. (The only exception is if your desalination plant is below sea level because then you have to pump the brine up hill, which costs some energy.)

I've seen the assumption that the brine dissipates quickly challenged.

Fluids can remain subbornly un-mixed, over large distances and for long times. Given that brine is heavier than seawater, it will almost certainly tend to sink and flow along bathymetric contours, perhaps pooling in local low spots. And sealife can be exceedingly sensitive to changes in temperature, ion density, salt content, etc.

This reminds me of a book in which an ecologist described a discussion with a chemist over the concentration of some pollutant in seawater. Roughly, "Assuming a well-mixed solution..." starts the chemist. "How are you planning to stir the oceans?" asks the ecologist....

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#113

Post by BrendanD »

Neliquat wrote: post #108
BrendanD wrote: post #79

Seeing as we are unable or unwilling to deal with the present micro and nano-particles resulting from decades of plastic use and disposal, I worry about the environmental effects of graphene.

Abspestos 2.0 Funny enough, its not actually banned in the USA, just a liability nightmare. I ocasionally still see brake pads with the stuff. I suspect graphine, and other 'nano' materials will be similar in practice.

That would be _malpractice_.

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#114

Post by jessriedel »

dredmorbius wrote: post #112
jessriedel wrote: post #52

Earlier quoted context omitted.

Are you talking about the brine? This is trivial if you just put a pipe a few hundred yards out to sea. The concentration is diluted extremely quickly. (The only exception is if your desalination plant is below sea level because then you have to pump the brine up hill, which costs some energy.)

I've seen the assumption that the brine dissipates quickly challenged. Fluids can remain subbornly un-mixed, over large distances and for long times. Given that brine is heavier than seawater, it will almost certainly tend to sink and flow along bathymetric contours, perhaps pooling in local low spots. And sealife can be exceedingly sensitive to changes in temperature, ion density, salt content, etc. This reminds me…

I've seen data on this and dilution was extremely fast, as expected.

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#115

Post by Accacin »

Xophmeister wrote: post #67

This is somewhat OT, but I've noticed a trend -- although I can't say how recent -- of headlines of the form "British [X] do [Amazing Thing]", particularly (but not necessarily) from the BBC. I note that the HN headline has been changed to "UK researchers" (IIRC, it said "British Scientists" earlier) and this BBC article doesn't actually use this phrase in their headline, but it appears prominently in the tagline. Th…

A quick search found this from 2013 so it's maybe just something they (the BBC) do: http://www.bbc.co.uk/news/technology-21442095

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#116

Post by emj »

Xophmeister wrote: post #67

This is somewhat OT, but I've noticed a trend -- although I can't say how recent -- of headlines of the form "British [X] do [Amazing Thing]", particularly (but not necessarily) from the BBC. I note that the HN headline has been changed to "UK researchers" (IIRC, it said "British Scientists" earlier) and this BBC article doesn't actually use this phrase in their headline, but it appears prominently in the tagline. Th…

I regularly see "Swedish X does Amazing thing" here on HN.

Re: UK researchers create graphene-based sieve that can remove salt from seawater

#117

Post by ptaipale »

threepipeproblm wrote: post #106
threepipeproblm wrote: post #103

Earlier quoted context omitted.

>> It's not new or surprising that a falling currency is good for exports and can fuel an economy. Except that was an argument promoted primarily by Leavers, who favored letting the currency fall, right? The majority who where against Brexit predicted severe economic problems for Britain as a direct consequence of leaving what was characterized as "safety" of the EU. The relevance seems obvious, because the opposite…

AP News: "The countdown begins: Britain to start EU exit on March 29" The markets are already factoring this in, dude. But that could be hard to see if you don't believe that markets embed any reliable information.

Exactly. Of course the markets only factor in what they understand, and sometimes they get it wrong.

But the relevant thing about it is that the market is betting in the real, hard money it trades with, not political punditry which is where the disaster is being pronounced.

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