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      CommentAuthorTrim
    • CommentTimeNov 23rd 2014 edited
     
  1.  
    Or go SPS in tandem with fission and fusion later.
    http://en.wikipedia.org/wiki/Space-based_solar_power

    Launch costs will have to come down below $200/Kg for this to be viable. Therefore railgun.
    • CommentAuthorAsterix
    • CommentTimeNov 23rd 2014
     
    I never forgave Jimmy Carter for essentially killing breeder reactor work in the US. Why we're still not using them makes absolutely no sense, but now the unwashed and politicians (washed and unwashed0 are afraid to bring the subject up.

    Show me a windmill-powered aluminum smelter. Materials cost energy and you're not going to get it from PVs.
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      CommentAuthorAngus
    • CommentTimeNov 23rd 2014
     
    Posted By: AsterixShow me a windmill-powered aluminum smelter.


    Probably not. But it is quite possible, and in fact highly economic to smelt aluminum with a renewable resource.. I don't think you really want to do it with fuels or nukes if you've got a choice.
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      CommentAuthoraber0der
    • CommentTimeNov 23rd 2014
     
  2.  
    Another remark that occurs to me about SPS: it would be very preferable to set up manufacturing in orbit or on the moon, provided that we can find a way to use mostly Moon materials to create the PVs. This would drastically reduce the amount of stuff we need to heave out of our gravity well.
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      CommentAuthorAngus
    • CommentTimeNov 23rd 2014
     
    Posted By: Andrew PalfreymanAnother remark that occurs to me about SPS: it would be very preferable to set up manufacturing in orbit or on the moon, provided that we can find a way to use mostly Moon materials to create the PVs. This would drastically reduce the amount of stuff we need to heave out of our gravity well.


    This is a novel idea to you?
    • CommentAuthorAsterix
    • CommentTimeNov 23rd 2014
     
    Posted By: Angus
    Posted By: AsterixShow me a windmill-powered aluminum smelter.


    Probably not. But it is quite possible, and in fact highly economicto smelt aluminum with a renewable resource.. I don't think you really want to do it with fuels or nukes if you've got a choice.


    Sure, but we're not talking about hydro here (my utility is a Bonneville customer). Great for making bombs too. While hydro is a nice developed technology, it's a limited resource, and I wonder how much of it there actually is that can be profitably exploited. Micro-hydro hasn't fulfilled its promise. You need mountains and a major river; low-head hydro hasn't really much headway.

    All of the other "renewable" sources aren't suitable for baseline, as far as I can tell.
  3.  
    Posted By: AngusThis is a novel idea to you?
    Don't be so snarky. Go ahead; give it a try. I for one get tired of your perpetual sniping.

    It's novel for politicians, that's for sure. Look at how many see the advantages in space-based manufacturing. There's so little vision out there.
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      CommentAuthorAngus
    • CommentTimeNov 23rd 2014
     
    Moi? Snarky?
    I'm hurt. Damaged, I tell you.
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      CommentAuthorAngus
    • CommentTimeNov 23rd 2014 edited
     
    Posted By: Asterix
    Posted By: Angus
    Posted By: AsterixShow me a windmill-powered aluminum smelter.


    Probably not. But it is quite possible, and in fact highly economicto smelt aluminum with a renewable resource.. I don't think you really want to do it with fuels or nukes if you've got a choice.


    Sure, but we're not talking about hydro here (my utility is a Bonneville customer). Great for making bombs too. While hydro is a nice developed technology, it's a limited resource, and I wonder how much of it there actually is that can be profitably exploited. Micro-hydro hasn't fulfilled its promise. You need mountains and a major river; low-head hydro hasn't really much headway.

    All of the other "renewable" sources aren't suitable for baseline, as far as I can tell.


    I wasn't just being difficult there. The source of all that water behind the dams is ultimately solar, of course, via evaporation from the oceans - and that's a huge collector. The other thing that evaporation does is desalinate the water, thereby storing even more power than you can get from the recondensation higher up the hill. Worldwide potential for that is on the order of potential for direct hydropower, and it doesn't require mountains, just rivers. And it has all the same properties as hydro for meeting demands.

    Right now renewables are about an order of magnitude behind fuel based systems. Is it completely impossible to imagine that efficiencies combined with newer renewables like salinity might close the gap?

    ETA Ref.
  4.  
    A couple of Watts per square meter is impressive to you?
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      CommentAuthorAngus
    • CommentTimeNov 23rd 2014 edited
     
    Per square metre of a thin, tightly wound membrane, why not? And that's for seawater-freshwater. If you were to co-opt more solar and wind as evaporating agents to make yourself some really salty water you can get up to maybe ten watts per square metre.

    We are talking millions of square metres of membrane in a single installation, and millions of square metres of evaporating ponds. No more impossible or ridiculously expensive than one or two other things that have drifted by here in recent times.

    And salinity generation facilities have already been built at pilot scale.

    A million square metres is a square kilometre. For comparison, worldwide paper production works out to the equivalent of 4 million square km per year.


    (Reorganised to make sense)
  5.  
    Posted By: Angus(Reorganised to make sense)
    I don't think so. A square kilometer for a measly megaWatt? That's many thousands of times less energy dense than 4th gen nuclear. Even the old CANDUs here
    http://en.wikipedia.org/wiki/Bruce_Nuclear_Generating_Station
    give 800 W/m2 of land area.
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      CommentAuthorAngus
    • CommentTimeNov 23rd 2014 edited
     
    Not counting the land aea needed for waste disposal ant for transit to it and the equivalent land area you must allocate for risk. How much land area around Fukuskima can't be used any more?.

    And why would it be unthinkable to have 800 sq m of membrane area per sq m of land area? Look at the surface area of your lungs for example..
  6.  
    Posted By: AngusNot counting the land aea needed for waste disposal ant for transit to it and the equivalent land area you must allocate for risk. How much land area around Fukuskima can't be used any more?
    These are small additive corrections and become insignificant when compared with the large multiplier in play here.

    And why would it be unthinkable to have 800 sq m of membrane area per sq m of land area? Look at the surface area of your lungs for example..
    That's interesting - a fractal approach, possibly. But does it work that way? How would it be constructed?
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      CommentAuthorTrim
    • CommentTimeNov 23rd 2014
     
    @Angus

    Thanks for the link, is the week or two up so that you can reveal more?

    @AP

    You are discounting a nice and important source of energy and fresh water.

    Do some searching on how much fresh water the Amazon alone mixes with the ocean.
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      CommentAuthorAngus
    • CommentTimeNov 23rd 2014 edited
     
    @AP
    Osmotic membrane mounts are already well developed and available for desalination and other purposes. Several types exist. Winding in a spiral is one. Another is to wind the membranes into small tubes and bundle the tubes. The issue in all cases is of course to get a leakproof connection to each side of the membrane good enough that you csn apply a lot of pressure. Also to support thr membrane against rupture.

    The particular membranes used in Reverse Osmosis and Forward Osmosis are not well optimised for PRO. That's ongoing.

    As the paper mentions there are also other processes than osmosis that could be used to extract salinity energy, though not yet so well developed.

    @Trim
    Still struggling with it. For a hint: seawater is a lot easier to get than freshwater in a lot of places.
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      CommentAuthorTrim
    • CommentTimeNov 23rd 2014
     
    Having a stronger draw fluid than saltwater and a decent membrane should enable fresh water to be drawn away from the salt water.

    That only leaves the problem of separating the fresh water from the draw chemical or chemicals at as low a temperature as possible, maybe reduced air pressure would help?

    A chemical like ammonia might fit the bill but would the fresh water be drinkable or just fit for plants?
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      CommentAuthorAngus
    • CommentTimeNov 23rd 2014
     
    A lot of issues to discuss in that comment. Closed cycle osmosis using reformable solutions is really interesting. My own minimal efforts are focussed on naturally occurring satine water solutions.

    I'm not quite sure if I understood something in what you posted. You don't get fresh water OUT if you make power from saline differences. You can combine mechanical power and salt water to get fresh water or you can put fresh water and salt water together to get power, but you can't do both at once.