Naked Science Forum
On the Lighter Side => New Theories => Topic started by: Nizzle on 24/08/2009 12:51:25
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Couldn't we make a huge ventilator (or more than 1) with a Carbon filter to collect excess CO2 from the air?
And then inject the CO2 in the ground, like in an already extracted, empty gas field, add some pressure to compact the CO2 and put a cork on it?
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It would probably be easier just to allow rain forests to expand so that they convert the co2 to oxygen and wood.
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And such rain forest would be prettier too, no doubt!
But unfortunately, mankind isn't ready yet for true ecological solutions.
Third world countries do have a point in saying that the first world countries have no right in holding back their "Industrial Revolution".
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Is it really true to say that the rain forests 'hold' all that much carbon? Two places where there is much more carbon held are in Carbonates (rocks) and in Fossil Fuels. How relevant is the rain forest, really, to the CO2 situation. I am deliberately ignoring the other effects of deforestation - climate and extinctions for the purposes of this post.
This link gives some figures (I haven't verified them but the sums look ok and the problem has been approached in a workmanlike manner).
www.hydrogen.co.uk/h2_now/journal/articles/2_global_warming.htm (http://www.hydrogen.co.uk/h2_now/journal/articles/2_global_warming.htm)
There's loads more of condensed info in the link; I recommend reading it - it's not too heavy going.
The present level (2000) is about 300ppm of CO2.
Burning fossil fuels is calculated to be contributing to the CO2 level by 6ppm each year, at the present rate (scary, or what!?).
According to the sums, burning the whole of the Amazon rain forest would increase the atmospheric CO2 by 76ppm. (That's about 12 year's worth of fossil fuel production).
The rain forest, per year, disposes of about 1.7ppm, which is just over half of the 3ppm which is the total due to natural mechanisms.
With 1kW per square metre of solar energy hitting the Earth, there is a limit to how fast any area of plants can fix Carbon. How much of this Carbon fixing is achieved by rain forest, with its many layers of leaves, compared with what could be achieved by any other plant ground cover? People talk as if the rain forest stays like concrete, once the big trees are removed. Can this be true? How much CO2 is the deforested bit fixing? Plant growth which gets eaten yearly won't solve the problem but every 'woody' plant can be fixing its own bit of CO2.
WMD, Swine Flu and UK Education all show that the Politicians just can't be trusted to assess situations correctly. Just what is the true situation and what are the real options?
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The real options are: See OP [:P]
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Implementation?
Could be a problem. The nice thing about plants is that they do the implementation for you.
Remember, we're talking of removing 26 billion tonnes of CO2.
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CO2 injection (http://www.sciencedaily.com/releases/2005/01/050110091718.htm) is already in use. But in the article they use waste CO2 from an ethanol plant, not filtered from the air to reduce greenhouse effect.
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I wonder if higher levels of CO2 increases the rate that plants grow? Most of the carbon in fossil fuels was once in the atmosphere and the stuff that became fossil fuels flourished in it.
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The problem is that physical processes that can separate the CO2 all take energy to drive them. Unless lots of energy is available to you from a very low carbon source (e.g. nuclear) you're going to emit more CO2 than you remove - and yes I do know that some materials naturally absorb CO2 but again these take energy (and hence, usually fossil fuels) to manufacture.
And, if you overcome all that, it'll take an awful lot of work to remove billions of tonnes....
I'm not saying it'll never be done, but it doesn't appear to be practical at the moment?
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So Chemist of TNS unite!
And find a cheap CO2-catcher that is harmless to put in the soil along with the C2O
Edit: Cheap in energy requirements
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I wonder if higher levels of CO2 increases the rate that plants grow?
Yes they do. About 40 yrs ago I saw a film about tomato (?) growing in Dutch(?) greenhouses. They piped the exhaust gases from their gas heaters back into the greenhouses and recorded significant increases in growth rate - but, of course, other limiting factors would apply to the achievable improvement.
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So Chemist of TNS unite!
And find a cheap CO2-catcher that is harmless to put in the soil along with the C2O
Edit: Cheap in energy requirements
= Plants, doesn't it?
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The key point, surely, is what you do with the plants? If you bury them, cool.. but if they end up burning off goes the CO2 again and, worse, if they degrade anaerobically you'll re-release the carbon as methane which is an even worse greenhouse gas than you started out with.
If someone can think of a way of encouraging those little carbonate-y shellfish things that fall to the bottom of the sea when they die and form sedimentary rocks that might be good... but I don't know how you'd do that.
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But the plants have done the difficult bit - very elegantly. You have to choose trees (woody), I guess, and bury them. (DIY coal / lignite / peat, in effect)
I'd still like to know what future there is in using deforested rain forest areas - or, indeed, what they are doing at the moment. It would be generations before the loggers would want to return. How well would 5m of depth of vegetation perform, compared with 20+m of the original? Should we be spreading (ethically produced) nitrates all over the denuded bits? How do the sums pan out?
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Ideally as you say coal/peat/(what's lignite?).
Although I wonder how much energy would be expended moving them to the burial site and how we stop them degrading to methane when they get there.. after all it's basically landfill of organic materials which is famous for releasing loads of methane. Given how many trees there have been over time and how little (relatively) coal there is, I imagine the conditions for forming carbon deposits rather than emitting gases might be quite demanding.
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"What's lignite"???????
Dint they teach you nuffin at school? It's a very soft brownish stuff that is on the way in the process of making coal. We'd always try to get that into essays - as you do.
If what you are implying about the difficulties of carbon fixing that way is true, how is it that the rain forest manages to cope with so much? Or is the real message that the rain forest, even left intact, would only be achieving a holding action? Is it really long-term fixing all that CO2? The same decay processes must be occurring there, too.
These damned statistics are very hard to assess properly.
Re the amount of coal vs trees, I seem to remember a statistic that said the total fossil fuel stocks only represent something like 10 years worth of (total) solar energy arriving on the Earth. Only a vague memory - perhaps someone has the real value?
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I don't know. I'd always assumed that the rainforest was primarily just holding carbon in and that the bulk of the effect of its destruction would be in the release of that carbon...
But as I say, that's an assumption (and one I've been making without thinking since I was about 15) rather than something I have any data for.
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Well, at least we're both on the dark.
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The biggest living carbon reserve isn't trees, it's all the sea/ocean algae.
And plants are indeed very efficient CO2 catchers, but they're too slow in doing so.
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The good thing about plants is that they are using solar energy. Whilst carbon capture technology may be a good thing when you are dealing with concentrated CO2 combustion products, you are dealing with 0.3% concentration in the air - requiring large areas for gas exchange and energy (from where?). Are we really short of acreage for plants?
There is a problem with possible Methane production from rotting plants - true - but at least you've concentrated the Carbon into solid form and that, in itself, is quite an energy demanding process. Perhaps it would be necessary to sterilise the dead plant material somehow before attempting to store it. How about a gamma ray source somewhere on the production line, followed by sealing the material?
Nizzie:
Perhaps the seaborne algae could be filtered off and packaged someway, after sterilisation, and dumped in ocean deeps, where it's cold.
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I don't think the oceanic trophic pyramid would like to see it's base being packaged, sterilized and sent off though..
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Trees are the obvious answer. Put it into this scenario:
Each day, two men come along and throw two shovels full of dirt on the floor. Another two men come by and clean it up. The system works.
Now, each day two men come by and throw two shovels of dirt on the floor and one man has to clean it up. The clean up takes twice as long.
In the future, three men come along and throw load after load of dirt on the floor and no one comes to clean it up. If you are surprised when the dirt piles up, you're an idiot or politician.
We pollute, trees filter. Increasing the dirt while reducing the trees is madness.
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We can't grow a rain forest but with a little piped in water we can grow soy beans and the like. I wonder how much more carbon is fixed by a rain forest than can be fixed by food crop plants.
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Well, it's a matter of density, isn't it? Or real estate, if you will. Like Manhattan, when you can't grow out anymore, you have to start going up, up, up. Soybeans would occupy the same area of land but they are only a few inches high. From that perspective, it is easy to see why trees are the best answer.
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But there is a problem when we want other nations to not do the things we have already done in order to become a wealthy nation. It might look to some like we just want to prevent the other nations from becoming wealthy like us.
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We can't grow a rain forest but with a little piped in water we can grow soy beans and the like. I wonder how much more carbon is fixed by a rain forest than can be fixed by food crop plants.
A lot of light / heat reaches the ground under a shallow layer of food crops. This reduces the amount of carbon which can be fixed. Also, food crops will rot quickly and give you more CO2 and Methane - unless you do something extra to them. This would be expensive - but Methane could be used instead of fossil fuels, of course.
Your second point about developing nations feeling that they have a right to a hefty industrial revolution is relevant BUT can the Earth afford to indulge that?
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If we are to discuss solutions, real ones, we can not be divided and clouded by drawing lines of separation. We are discussing what is good for the planet, not one person or another or one nation or another. Just because human ignorance and pettiness get in the way of a solution, does not mean that it is not the right idea.
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Maybe the underlying point I'm getting to is that any fixing that is done will have to be done by nations that have already experienced the industrial growth. This probably won't happen until some driving force leads the way. Profit has been a driving force to get us where we are. Maybe there is a way to develop so that doing the right thing for nature is profitable.