I was thinking about co² production and stacks on factories and Electric plants.
smog2.jpg
I began thinking about ionizers and supposed air purifiers sold in the home, and at bars to Zap Cig smoke.

My question is, can CO² coming from stacks like these be broken down into carbon and o² (also producing ozone as a by product)?

Yes, you could crack CO2 into C and O2. However, the amount of energy this would require would be very large. So much that it is not practical. But what has been developed are methods for extracting CO2 from flue gases. Then this CO2 can be stored, presumably underground. This process may take about a quater of the energy produced by a coal burning plant. CO2 has been pumped underground for a long time as an oil extraction method so we know it should stay down there for a long time in a geologically suitable region.

And it's not a dumb question. There are no dumb questions, just dumb answers.

I don't see that as a dumb question. In fact, if it could be done, it would definitely be the best possible thing to do. The logistics on the other hand would be very difficult. Like water, carbon dioxide is a burnt substence, the end result of an energy releasing reaction (not sure what the technical word is) Any effort to sperate the molocule would require considerable energy. I am not sure it would be practical to do this in smokestack. However with the right catalyst, this could be done in a lower energy environment. After all, plants do it.
While writing this, I searched the internet and I found this. http://technology.newscientist.com/a...into-fuel.html
Very fascinating, from what I understand of the temperatures involved it could be done on site, using waste heat for part of the reaction. On the other hand I would prefer a reaction that released oxygen. From what I understand about mini article it may be possible. http://cat.inist.fr/?aModele=afficheN&cpsidt=1944444
This is very exciting.

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That's what I thought.
Sometimes the chemistry is a simple reaction. Sometimes it isn't...

I don't see storing it underground as necessarily a solution by any means. Maybe someday, we will develop easier and more efficient ways of separating the elements.

Yes, there is such a thing as a Dumb Question.
I've heard tons of them.

Ever seen Clerks?

Would any of this work for Nitrous Oxide?

From what I've read, Nitrous Oxide is about over 200 times as worse as Carbon Dioxide, even if only a little bit of it gets into the atmosphere; it lasts for a very long time when it does, though. Methane would also be a problem.

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"A long habit of not thinking a thing wrong gives it a superficial appearance of being right." -- Thomas Paine

Being intelligent is not a felony. But most societies evaluate it as at least a misdemeanor. -- Heinlein

Creationists make it sound as though a "theory" is something you dreamt up after being drunk all night. -- Isaac Asimov

Another possibility that has been suggested is to use CO2 produced by burning coal and natural gas to feed algae used to produce biodiesel. This carbon will be released into the atmosphere when the biofuel is burned, but is better than using oil instead of algae biodiesel.

Not the same reaction, though we already have several methods in place to remove NO and NO2. They are known as catalytic converters, and I am fairly sure they could be used in a smokestack system. They may be already. As for some already in the air, many freestanding versions, not connected to a polluting source, could be used to help. Say an extra one added to your car, that removes the stuff already in the atmosphere. As for methane. I am not sure.
http://auto.howstuffworks.com/catalytic-converter.htm

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Nitrous Oxide can generally be controlled by not creating conditions that produce it when burning fossil fuels. Modern cars and power plants are supposed to produce very little N2O. It is greenhouse gas with the fourth largest total warming effect in the atmosphere after water vapour, carbon dioxide and methane. Methane is not released by power plants as it burns well and releasing it means you're wasting money.

Suppose we wish to crack CO2 to C and O2. We need energy to do this. For simplicity, suppose the energy comes from burning carbon, since essentially our available marginal energy sources are of this nature. The laws of thermodynamics indicate that processes have less than 100% efficiency, so the amount of CO2 emitted from carrying out the cracking is larger than the amount of CO2 we crack, catalysed or not.

Essentially, given that we are burning carbon for our marginal energy needs, it would be better to use any energy we have to do something we need to do, rather than to crack the CO2. The only situation we would want to use energy to crack CO2 rather than do something useful is if it can be done using some energy that otherwise cannot be usefully used to do something. For example, some remote solar panels in the desert which cannot be practically joined to a grid might be set to crack carbon when they aren't doing anything else useful. But it might be more efficient for them to sequester it in some way instead.

This kind of argument also shows the absurdness of turning food crops into alcohol for fuelling cars. Much more energy can be got out of the land by growing biomass for powerstations. Since there are plenty of powerstations burning fossil fuel, we produce less carbon by fuelling cars with oil and burning the biomass in the powerstations. Of course if we can create cellulosic ethanol from cornstalks that's brilliant, but I suspect it would still be better just to burn them in a powerstation. On the other hand burning fossil fuels in cars produces localised urban pollution, which is lessened with ethanol, so on those grounds it might be better to have more cars burning ethanol.

Yes, but as you said, that is under the assumption the energy comes from a carbon source. I don't think any SINGLE source will ever replace a carbon based energy economy, but several sources, both in development and already in place, do have the potential to do so. Even today we have several sources that could be used, such as focused energy solar, hydroelectric , and nuclear. No one is saying it wouldn't be difficult, or not expensive, but sometimes we need to do something not because it is easy, but because it is hard. This blue marble is all we got, and while I hope for more, we still must work maintain what we have. We are but custodians, and I would prefer to get my damage deposit back.

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I was looking at Wikipedia and carbon dioxide has many uses so it is not all bad, in fact a very useful product. You could commercially separate the gas by bubbling the smoke through water just to capture it. From there it could be used as a greenhouse gas separated from the normal atmosphere to assist plant growth.

Again it is a Wiki reference but apparently carbon dioxide is so low for effective green plant growth that it is near suffocation level for plants. It wouldn't be an energy intensive carbon cracking exercise but the scale of enclosed improved plant production would be enormous. It would be a three step process. First burn to produce it, second capture in water and third use in food or fuel production through improved greenhouse plant growth.

Steps one and three are already commercially viable but the size of step three is not even close to handling the volume of carbon dioxide available.

Does that help?

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"Nature is obliged to let reality determine its laws, whereas mathematics is under no such constraint."

Here is an article from 30 April 2007 issue of Chemical & Engineering News about chemical processes to use CO2.
The Amine process is getting much more attention commercially as a CO2 capture process than using water. There are actually some commercial pilot scale facilities in use (IEEE link).

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At night the stars put on a show for free (Carole King)

Thank you Swift,

Carbon dioxide is a very useful gas and would be very useful in higher concentrations in a number of areas, just not so good for us in the atmosphere.

Cheers

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"Nature is obliged to let reality determine its laws, whereas mathematics is under no such constraint."

Agreed, Carbon Monoxide is also a very useful industrial gas, but I most certainly don't want to go around breathing the stuff.

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Look at it this way. When you burn coal with oxygen you get carbon dioxide and heat from the exothermic reaction:

C + O2 > CO2 + heat

To make it go the other way (an endothermic reaction)

CO2 + heat > C + O2

requires the same amount of energy as the forward reaction. Even with 100% efficiency you would just be using up all the energy released in burning to put things right back where they started.

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Wouldn't that be carbon plus Ozone if you are adding heat (oxygen)?

Um, I guess if you have enough heat to crack CO2 you'd have some ozone forming, which is toxic and a short lived greenhouse gas. Another problem is, if you are doing this with normal air, you'd probably also get nitrogen oxide forming, which is a long lasting greenhouse gas. If you want to crack CO2 the easiest way might be to just grow some plants.

I suppose you could have a combined nuclear/coal plant. The nuclear plant would provided baseload power while the coal plant produces synthetic gas from coal that is stored and used for peak power. During periods of low power use nuclear power could be used to crack CO2 produced from the coal side of things. However, I think it would be easier to just bury the CO2, or perhaps use it to produce synthetic liquid fuel if the market price is high enough. (People are currently willing to pay over ten times more for liquid fuel they can burn in their cars than for the same amount of energy in a lump of high grade coal.)

It is important to remove polutants before waste gases are released into our atmosphere. I don't think any of the above mentioned processes are suitable for cleaning polutants from air when the polutants are a few parts per million. Slacked lime = Ca(OH)2 will absorb some these polutants, but then we are stuck with mountains of poluted lime. Worse the slacked lime is presently made from limestone and the carbon dioxide is released into our atmosphere. I presume the hot carbon dioxide can be removed from new design lime kilns at considerable cost, but this is not often done at present. Neil

While ozone is desirable in the upper atmosphere, we do not want to breath even one part per million ozone. Since ozone is heavier than air, there is at present no practical way to get surface ozone about 90 kilometers higher. Neil