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Posts Tagged water

A very different form of mining… Aimee Whitcroft May 18

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I came across this last week, and thought it was certainly an interesting way of addressing New Zealand’s mining issues.

clouds

The conversation around whether, and if so to what extent, New Zealand should mine its national parks for mineral resources is a heated (haha) one.  And, I might add, not one into which I’m going to assert myself.

Now, someone* has gone and suggested another way that New Zealand could benefit from mining but, wait for it, without having to open ground at all.  How, you say?  By water mining.

Yes, dear readers, you read that correctly.  Water mining.  Now, I know the term evoked for me images of men with shovels**, down shafts, trying vainly to lift water.  Or something.  But it’s not that at all.  Instead, it basically means harvesting the inevitable product of cloud seeding – water.  And, certainly, atmospheric moisture which could be turned into rain/snow is something of which we’re not short.  Not at all.  I live in Wellington, and sometimes would be quite happy if it were less…precipitous…here.

So how does cloud seeding work?  Well, it’s something humanity’s been playing with for a while now.  I won’t get into some of the mad conspiracy theories about Soviets/Americans and secret programmes, but the science itself has been around for a few decades.  There are different ways of doing it, but one of the ways we kiwis would consider is through the addition of small amounts of silver iodide crystals into the high bits of clouds, where water droplets are hanging about at less than zero degrees C.  Apparently, said addition triggers a reaction which makes the droplets freeze – they then begin to fall, turn back into water on the way down, et voila!  Rain.  Or, possibly, snow if they hit a mountaintop on the way down.  Either way, it’s accessible precipitation.

You can also use dry ice, which works slightly differently: it cools the surrounding air so quickly that water vapour reverse-sublimes straight into ice.  Hoo-har.  It should be mentioned that existing water droplets are still needed, though, to ensure the ice crystals can grow large enough for them to descend from the heavens.

And cloud seeding can be done either by aircraft, or from the ground.

Of course, this sort of technology can also be used to suppress fog and rain.  This is important for airports.***  )r the opening ceremony of 2008’s Olympic Games in Beijing.

Anyhoo, back to thoughts of using it here.  It might well work, for example, in the Southern Alps to increase Canterbury’s water supply (good for irrigation and energy production).  And we needn’t, according to  Assoc. Prof. Bardsely, worry that it would decrease Canterbury’s winter rainfall.

Issues to consider?  Well, primarily the safety aspect of it, to be honest.  Silver iodide is a pretty toxic substance, but it’s only harmful if encountered in an intense or continued fashion.  Chronic exposure doesn’t count, apparently. And studies looking into its accumulation in the environment haven’t been able to pick up anything above normal background levels.  Our neighbours over the Tasman are experts on this, it would seem, as they’ve been using cloud seeding for some time, and so have been studying its effects.  The verdict of peer-reviewed science as to its danger?  It’s fine.****

So, an interesting idea!  And it does sort of make sense – given that we have a natural resource in abundance, and one which is unlikely to run out soon (in fact, climate change scenarios suggest parts of NZ might get wetter and wetter) and requires no breaking of ground, perhaps it’s something to be seriously considered.

Thoughts?

…

And no, I’m not pleased that Wellington’s going to get colder and soggier.  Luckily this is a brilliant city despite that.

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*Associate Professor Earl Bardsley, of the Department of Earth and Ocean Sciences, University of Waikato

** Or spades.  Shovels might work marginally better, though

*** Although clearly it was not in use the morning I got fogged in at Hamilton airport. For a while.  Very sleep deprived.  Hurrah for Foyle’s War and my netbook…

**** Well, according to the Weather Modification Association

Hydrogels or, how to replace petroleum-based plastics Aimee Whitcroft Feb 04

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Well, wonders will never cease.  Not only is water already one of the strangest,and most interesting fluids/substances around, but clever scientists from the University of Tokyo just added another layer of WTFness.

hydrogel small

A hydrogel (with hair). Credit: Nature 463, 339-343 (21 January 2010) | doi:10.1038/nature08693

In essence, they have developed a sort of non-fluid, yet still transparent and flexible, water.  A hydrogel.  That’s flexible.  And transparent.  (That was worth repeating).  I’ve seen a reference on the web to ‘elastic water’ but thought that was pushing it a bit far.

Published in the Jan 21 edition of Nature, the paper outlines how the researchers were able to create a high-water-content hydrogel using only water, a bit of clay, and a pinch of organic components (details below).

‘But why’, I hear you ask.  ‘We already have other plastic materials – they’re called, you know, ‘plastic”, I hear you say.  And that’s the problem – they’re all based on petroleum, which is based on oil, which is an increasingly unsustainable thing on which to be based.  You know, what with the inevitability of world oil supplies beginning to decrease and stuff.

So scientists feel it’s reasonable to start exploring other means of constructing plastic materials.  Plastic in the true sense of the word: flexible and mouldable.  Hydrogels – flexible water-based gels – seem an obvious thing to start looking into (and of course we won’t get into the water debate here).

The recipe for this hydrogel goes something like this:  take some water.  Add about 2-3% by mass of clay.  Mix, and add 0.4% by mass of certain organic components*.  Shake well, at least metaphorically, for 3 minutes or a bit longer.

And voila! The final product is a transparent hydrogel with some very interesting properties.  It’s able to stick together, which means it can easily be built into structures etc.  It also keeps its shape, so any structures it’s used for can be free-standing – all due due to its ‘outstanding mechanical strength’.

It’s able to self-heal when damaged, and preserves biologically active proteins for catalysis (great for setting up reactions involving enzymes).  In fact, it has some interesting applications for building reaction sequences using blocks containing different enzymatic activities.

Hydrogel structures

Hydrogels structures (blue and clear). Hydrogels with and without 0.01% methylene blue (for visibility) were prepared using 3.0% CNS, 0.21% G3-binder and 0.09% ASAP, and cut into small blocks. a, b, A bridge constructed by connecting together seven hydrogel blocks can be suspended horizontally (a) and held vertically (b). Diffusion of methylene blue from one block to the other hardly takes place, probably because of its adhesion to the CNS surfaces. c, d, Pictures of a heart-shaped hydrogel object before (c) and after (d) being immersed for 6 h three times in fresh THF at 20 °C. Credit: Nature 463, 339-343 (21 January 2010) | doi:10.1038/nature08693

Most hydrogels have poor transparency, are brittle and can’t self-heal.  In addition, making them is an involved process of multiple iterations of heating and cooling, agitation using sound, and in situ polymerisation or crosslinking reactions.  Our little hydrogel, however, is the polar opposite.  It’s transparent, flexible, and great for building structures with.  It’s easy to make – All one requires is water, the three ingredients, and mixing at room temperature for a few minutes (as few as 3).  In addition, it’s able to persist in briny or pH-positive/negative (acid or alkaline, folks) conditions, and can, with the addition of a couple more compounds, even be made using salt water itself.

I mean c’mon – it’s even environmentally friendly!  I’d take this hydrogel home to meet the parents, as it were.

In short, this hydrogel is going where no hydrogel has gone before, and kudos goes to Wang et al – great work, guys.

Reference:

Wang Q, Mynar JL, Yoshida M, Lee E, Lee M, Okuro K, Kinbara K, & Aida T (2010). High-water-content mouldable hydrogels by mixing clay and a dendritic molecular binder. Nature, 463 (7279), 339-43 PMID: 20090750

*In their words: “CNSs, a dendritic macromolecule (Gn-binder; n, generation number) and sodium polyacrylate (ASAP)”

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