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Carbon sequestration

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BDA
954480.  Thu Dec 06, 2012 7:37 am Reply with quote

Anybody have an interest/knowledge in CO2 sequestration and it's workings. Specifically if it possible to obtain a pure carbon form from CO2.

 
Efros
954485.  Thu Dec 06, 2012 8:02 am Reply with quote

Yeah it's possible but it would require a large investment of energy. 393.5 kJ per mole would be required to convert CO2 back into C and O2. That's 100% efficiency, and would yield 12g of Carbon, using the entire output of Hunterston B Nuclear power station (1000 MW) you could make about 3 kg of carbon per second. Globally about 1,000,000 kilos of CO2 are released per second, so if you had 1/3 of a million 1000 MW nuclear power stations you could offset the global release of CO2. Sequestration is much better handled by nature, by locking the CO2 up as limestone etc.

 
BDA
954516.  Thu Dec 06, 2012 9:15 am Reply with quote

thanks Efros. good knowledge. are you a chem engineer?

 
Efros
954518.  Thu Dec 06, 2012 9:30 am Reply with quote

Chemist.

 
BDA
955910.  Wed Dec 12, 2012 1:13 pm Reply with quote

Efros.

Would you mind if i asked some more simple questions?, to do with chemistry of course.

 
Efros
955911.  Wed Dec 12, 2012 1:17 pm Reply with quote

depends, as I tell my students I'm not a walking text book but I will explain.

 
BDA
955937.  Wed Dec 12, 2012 3:09 pm Reply with quote

please tell me if i over step the mark.

i am a masters of architecture student. i proposing an R&D centre that looks at Carbon sequestration technique. Takes the sequestered carbon and re-applies it through construction into the built environment. Potentially within building facades, maybe even as a structural element itself. I appreciate that current sequestering techniques are fledgling and costly but i mainly want my project to have a solid base of possibility rather than upfront practicality.

hence the question re: breaking carbon dioxide down into its constituent parts.

my chemistry knowledge isn't the best and the internet can be a mis-leading and confusing place. But hence why i threw the question out on this forum.

so it's the case of answering question of a simpleton really to tick a few boxes.

Andrew

 
Efros
955939.  Wed Dec 12, 2012 3:17 pm Reply with quote

Ok sounds good, go for it, ask away.

TBH I think the path for sequestration/cycling would be much better served using biological agents than industrial chemistry ones.

http://www.extremetech.com/extreme/124383-bacteria-converts-carbon-dioxide-into-liquid-fuel


this is an interesting development and I think probably a path we'll walk down increasingly in the future.

 
Celebaelin
955946.  Wed Dec 12, 2012 4:05 pm Reply with quote

Why does it have to be pure carbon? Plant a tree for goodness sake! Biofuels won't sequester carbon for anything like as long as it would be locked away in wood used in construction projects!

I'm interested about how you'd utilise pure carbon in construction but surely the expense makes wood the sensible answer?

 
Efros
955962.  Wed Dec 12, 2012 5:16 pm Reply with quote

Biofuels don't sequester but cycle the carbon, I agree plant trees. My point was that the chemical sequestration costs too much in energy terms, we need to look at the bio side, trees is one but there are many possibilities with advanced bio/genetic engineering coming to the fore. Of course the sensible approach would be to stop using the bloody fossil fuels in the first place, replacing them is the bugger though.

 
BDA
960307.  Thu Jan 03, 2013 6:42 am Reply with quote

Efros.

Happy New year.

So after a little gap back to carbon production.

In your post 954485. Thu Dec 06, 2012 9:02 am, what would be the volume of CO2 to produce the 12g of carbon?

What is the process for converting the CO2 into carbon plus oxygen? Obviously addition of the energy we talked about but what would the procedure look like?

are you aware of the process of making Carbon Fibre?

 
Efros
960318.  Thu Jan 03, 2013 7:26 am Reply with quote

12g of carbon is the molar mass of carbon, i mole of carbon in a mole of CO2 and the molar volume is 22.4 dm3 at STP. There is no single process for the decomposition of CO2 there are many, what they have in common is the use of elevated temperatures in excess of 300C and also the use of catalysts. Even with catalysts 300C appears to be the lowest temperature that is feasible. Carbonization, the process used to make carbon fibre would not be a suitable method to split CO2 as the heat required would be too high. Scientists in Finland have proposed a mineral method which may be suitable for reducing their C footprint by a small amount but it wouldn't be feasible for any of the major industrialized nations.

 
BDA
960342.  Thu Jan 03, 2013 9:07 am Reply with quote

so are you saying that that even if we separate the carbon from the CO2 with 300C+ and a catalyst it's not feasible to then create PAN (Polyacrylonitrile) necessary for Carbon Fiber Production?

 
Efros
960368.  Thu Jan 03, 2013 10:13 am Reply with quote

You could make PAN from carbon, but it is not common, or indeed easy or efficient, to make this sort of thing from scratch as it were.

 
BDA
960376.  Thu Jan 03, 2013 10:31 am Reply with quote

i understand this would be a very niche operation. but I'm more looking at possibility as oppose to up front practicality. every process has to start somewhere eh.
so in essence:

Catch Air. Isolate CO2. Break into C + O2. Carbon into PAN. Create Carbon Fibre. use Carbon Fibre to make Carbon Fibre Reinforced Polymer ie sports products, building elements etc.

Ideally Without relying on fossil fuel to create the energy required for the reactions ot take place. Although i suppose unless use nuclear this is a bit wishful?

 

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