1. Joined
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    28 Jul '13 09:255 edits
    According to this article:

    http://phys.org/news/2013-07-harvesting-electricity-greenhouse-gas-carbon.html

    they are proposing making electricity from waste CO2 by: “...react the CO2 with water or other liquids and, with further processing, produce a flow of electrons that make up electric current. ...”

    But, since CO2 is carbon that has been fully exothermically oxidized, how on earth are they proposing to extract any net useful energy from it when no further exothermic oxidation is possible? I don't see how you could do much with CO2 other than get it involved in endothermic reactions rather than exothermic reactions and the problem with that is that endothermic reactions require a net ABSORPTION of energy rather than a net release of energy so how on earth can you generate ANY useful amounts of energy from such a reaction let alone electrical energy!?

    This doesn't make any sense to me so what am I missing here?
    Or does this really make no sense and hey are just talking crap!!!!?
    anyone?

    perhaps where they kept quoting "CO2" and "carbon dioxide" it was actually supposed to be "CO" and "carbon monoxide" they should have been quoting? -that would make a lot more sense! But, if so, what a bad edit error to make!
  2. Cape Town
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    28 Jul '13 09:46
    Originally posted by humy
    But, since CO2 is carbon that has been fully exothermically oxidized, how on earth are they proposing to extract any net useful energy from it when no further exothermic oxidation is possible?
    http://en.wikipedia.org/wiki/Carbonic_acid
    If you put CO2 in water you get carbonic acid. Acids can generate energy. So you must be missing something.
    I couldn't find any energy of reaction mentioned on the wikipedia page though.
  3. Standard memberDeepThought
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    28 Jul '13 10:233 edits
    Originally posted by humy
    According to this article:

    http://phys.org/news/2013-07-harvesting-electricity-greenhouse-gas-carbon.html

    they are proposing making electricity from waste CO2 by: “...react the CO2 with water or other liquids and, with further processing, produce a flow of electrons that make up electric current. ...”

    But, since CO2 is carbon that has been fully exoth quoting? -that would make a lot more sense! But, if so, what a bad edit error to make!
    No you haven't missed anything, this is energy of mixing. It's not chemical energy released by building molecules, it's the energy released when something dissolves. As a way of generating power it's unrealistic - the total energy to be produced annually is 1570TWh (from the article) for a power of 179GW the article's abstract gives an energy density is 4.5 mW/m^2, so this gives an area of electrolite of 3.98 * 10 ^ 13 m^2. The surface area of the earth is 5.1 * 10^14 m^2. Ho ho ho.
  4. Joined
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    28 Jul '13 11:34
    Originally posted by DeepThought
    No you haven't missed anything, this is energy of mixing. It's not chemical energy released by building molecules, it's the energy released when something dissolves. As a way of generating power it's unrealistic - the total energy to be produced annually is 1570TWh (from the article) for a power of 179GW the article's abstract gives an energy density i ...[text shortened]... rolite of 3.98 * 10 ^ 13 m^2. The surface area of the earth is 5.1 * 10^14 m^2. Ho ho ho.
    this is energy of mixing.

    the link said:
    “...react the CO2 with water or other liquids and, with further processing, produce a flow of electrons that make up electric current. ...”
    I took the “with further processing” part to indicate this doesn't work merely as a result of CO2 mixing with water.
  5. Joined
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    28 Jul '13 11:524 edits
    Originally posted by twhitehead
    http://en.wikipedia.org/wiki/Carbonic_acid
    If you put CO2 in water you get carbonic acid. Acids can generate energy. So you must be missing something.
    I couldn't find any energy of reaction mentioned on the wikipedia page though.
    Acids can generate energy.

    Yes, that makes sense but only up to a point. For example, you could react carbolic acid with a pure metal to make a metal-carbonate salt and H2 and then you could then, either by burning that H2 or putting it through a fuel cell, use it as a source of energy (while the metal-carbonate salt would, presumably, most likely be just chucked as a waste byproduct ) .
    However, the problem with that is that you would probably need to input a lot more energy to first purify the metal from it's ore than what would be outputted from reacting that metal with carbonic acid thus there would likely be no net gain of energy!
    I couldn't find any energy of reaction mentioned on the wikipedia page though.

    -and that's the problem. It is difficult to guess what possible reaction they could be talking about.
    Can anyone here give an example of just such a reaction with carbonic acid with other reactants where it would not take more energy to obtain those other reactants in the required form than the energy you would get out of reacting carbonic acid with those other reactants?
    Because, so far, I can't. And I have studied chemistry.
  6. Standard memberDeepThought
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    28 Jul '13 12:00
    Originally posted by humy
    Acids can generate energy.

    Yes, that makes sense but only up to a point. For example, you could react carbolic acid with a pure metal to make a metal-carbonate salt and H2 and then you could then, either by burning that H2 or putting it through a fuel cell, use it as a source of energy (while the metal-carbonate salt would, presumably, mo ...[text shortened]... ic acid with those other reactants?
    Because, so far, I can't. And I have studied chemistry.
    http://pubs.acs.org/doi/abs/10.1021/ez4000059

    is a link to the abstract of their paper, they have a diagram to show the kind of set up they have in mind. They have porous electrodes - Maxwell's demon? They claim to generate 4.5 milli-Watts per metre squared. This is not a realistic way of solving the problem of emissions of CO_2.
  7. Joined
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    28 Jul '13 12:106 edits
    Originally posted by DeepThought
    http://pubs.acs.org/doi/abs/10.1021/ez4000059

    is a link to the abstract of their paper, they have a diagram to show the kind of set up they have in mind. They have porous electrodes - Maxwell's demon? They claim to generate 4.5 milli-Watts per metre squared. This is not a realistic way of solving the problem of emissions of CO_2.
    Arr so you were correct; they WERE talking about the energy from mixing after all!
    Well, practical or not, at least that makes sense now.

    Just a thought:

    The byproduct of the reaction is a carbonic acid solution.
    Why not pump that solution either underground or to the ocean bottom where the carbon would be thus prevented from entering the atmosphere for a very long time and thus prevent that carbon causing global warming for a very long time?
    Even if there isn't much extra energy to be gained from the reaction for it to be worth doing purely for that reason alone, it may be worth it as a form of carbon burial?
    I think this idea is one definitely worth looking into!
  8. Cape Town
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    28 Jul '13 15:01
    Originally posted by humy
    Why not pump that solution either underground or to the ocean bottom where the carbon would be thus prevented from entering the atmosphere for a very long time and thus prevent that carbon causing global warming for a very long time?
    Even if there isn't much extra energy to be gained from the reaction for it to be worth doing purely for that reason alone, it ...[text shortened]... e worth it as a form of carbon burial?
    I think this idea is one definitely worth looking into!
    Carbon sequestration is already being done. However it takes energy to separate the CO2 out of the power station exhaust. Also, transporting it is done by compressing it to a liquid then pipelining it and pumping it underground. All this takes 1/4 of the power output of the power station. (in one example I heard about).
    So the question is who is going to pay for all this?
    One solution is to use the CO2 to increase the output of oil wells as this provides a financial benefit.
    But as long as there are so many people willing to let the world burn so long as they don't have to pay for it now (global warming deniers), there will be few policies that encourage doing something about the CO2 emissions.

    Here is where I got some of my info:
    YouTube

    They also talk of making fertilizer out of some of the byproducts.
  9. Joined
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    28 Jul '13 15:09
    Originally posted by twhitehead
    Carbon sequestration is already being done. However it takes energy to separate the CO2 out of the power station exhaust. Also, transporting it is done by compressing it to a liquid then pipelining it and pumping it underground. All this takes 1/4 of the power output of the power station. (in one example I heard about).
    So the question is who is going t ...[text shortened]... e.com/watch?v=R7julP7hkCA

    They also talk of making fertilizer out of some of the byproducts.
    Of course the better solution is to use nuclear power and not to emit CO2 in
    the first place.

    However that would be the sensible thing to do, and politicians can't do that.
  10. Subscribersonhouse
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    28 Jul '13 15:19
    Originally posted by DeepThought
    No you haven't missed anything, this is energy of mixing. It's not chemical energy released by building molecules, it's the energy released when something dissolves. As a way of generating power it's unrealistic - the total energy to be produced annually is 1570TWh (from the article) for a power of 179GW the article's abstract gives an energy density i ...[text shortened]... rolite of 3.98 * 10 ^ 13 m^2. The surface area of the earth is 5.1 * 10^14 m^2. Ho ho ho.
    Even if they did all that, 180 gigawatts is still a drop in the bucket of the world's consumption of energy, like 100 times more or thereabouts. If they were talking about 180 TERAwatts they might have something.
  11. Joined
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    28 Jul '13 16:45
    Originally posted by sonhouse
    Even if they did all that, 180 gigawatts is still a drop in the bucket of the world's consumption of energy, like 100 times more or thereabouts. If they were talking about 180 TERAwatts they might have something.
    180 Gw is not to be sniffed at... If it didn't require almost the entire Earth's
    surface to achieve it...

    I think you meant 18 TW however... Which is in line with wiki's average
    world power consumption of 15TW for 2008.

    Having worked with acids in chemistry class I know that diluting/mixing them
    does produce heat energy... but at such low density it just wouldn't occur to
    me to try to harness it as a major energy source...

    Efficient power generation requires a large thermal differential between your
    heat source and your heat sink.
  12. Cape Town
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    28 Jul '13 20:21
    Originally posted by googlefudge
    However that would be the sensible thing to do, and politicians can't do that.
    Its not entirely about politicians, although they could steer it in that direction. The fact is that nuclear is so highly regulated that its not the best economical choice for investors. The other major problem is that regulation means that it is much harder to try new designs than old ones, so nobody is willing to try new designs as the regulatory hurdles are too big.
    One commentator I heard recently reckons China will try all the new designs first then the US will buy them from China once they have been proven.
    The best thing politicians can do is push up the cost of fossil fuels sources though some sort of carbon tax as this would make both nuclear and renewables more attractive (as well as carbon sequestration ideas).
    However, the US political system is money driven and as long as the majority of power is fossil fuels, they will drive the policies in their favour.
    The moment renewables become big enough and profitable enough that they have more money for lobbying than the fossil fuel crowd, things will change, but that is a long time from now.
    So for now, I have to support my own country which is 100% hydroelectric powered!
  13. Joined
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    28 Jul '13 20:295 edits
    Originally posted by twhitehead
    Carbon sequestration is already being done. However it takes energy to separate the CO2 out of the power station exhaust. Also, transporting it is done by compressing it to a liquid then pipelining it and pumping it underground. All this takes 1/4 of the power output of the power station. (in one example I heard about).
    So the question is who is going t e.com/watch?v=R7julP7hkCA

    They also talk of making fertilizer out of some of the byproducts.
    Carbon sequestration is already being done. However it takes energy to separate the CO2 out of the power station exhaust.

    Not according to the link. According to the link, you can make a net gain of energy (albeit only a small one ) from collecting that CO2 gas by dissolving it in water in the form of carbolic acid.
    Also, transporting it is done by compressing it to a liquid then

    but you wouldn't have to compress it much if at all if it was in a solution of water in the form of carbolic acid -right? just be careful not to shake it about too much!
    then pipelining it and pumping it underground.

    why not pipe it not underground but rather to the water at the ocean floor where it would take a few centuries to work its way to the surface by which time we would have surely developed highly economic renewable energy and also economic ways of removing CO2 from the atmosphere and preforming more permanent kinds of carbon burial on it?
    -this is my main idea here. It shouldn't take much energy to pipe it there once you got the pipes all the way down to the ocean floor. In fact, thanks to gravity doing the work for you, you could even use the movement of that water from the power station to sea level within the pipe to generate a small amount of energy in the form of hydroelectric energy!
  14. Standard memberDeepThought
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    28 Jul '13 21:05
    Originally posted by humy
    Carbon sequestration is already being done. However it takes energy to separate the CO2 out of the power station exhaust.

    Not according to the link. According to the link, you can make a net gain of energy (albeit only a small one ) from collecting that CO2 gas by dissolving it in water in the form of carbolic acid.
    [quote] Also, ...[text shortened]... evel within the pipe to generate a small amount of energy in the form of hydroelectric energy!
    The main way to reduce carbon emissions is to reduce power use, which in the U.K. means taking a hard look at the housing stock and making it thermally efficient. We have lighting when nobody needs it and so on. Carbon offsets and sequestration should be to reduce what we can't avoid burning, not to allow landlords to put off improving their insulation.
  15. Cape Town
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    28 Jul '13 21:34
    Originally posted by humy
    Not according to the link. According to the link, you can make a net gain of energy (albeit only a small one ) from collecting that CO2 gas by dissolving it in water in the form of carbolic acid.

    why not pipe it not underground but rather to the water at the ocean floor where it would take a few centuries to work its way to the surface by which time w ...[text shortened]... of removing CO2 from the atmosphere and preforming more permanent kinds of carbon burial on it?
    That depends on what sort of volumes of water we are talking about. Maybe you can double check DeepThought's calculations for us. What volume of water is needed to dissolve 1 ton of C02?
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