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Alberto says: July 22nd, 2009

Please let me give you some Thermodynamics topics concerning your idea, how you talk about it.

1-You mine CaCO3 (let’s say 1 tonn) … spending energy…
2-You heat CaCO3 to extract CaO (you’ll need to heat to over 900°C… a lot of energy, at least 6 MegaJoules per 100g)
3-Once heat, CaCO3 will absorb 176 KJoules/100g (about 1760 Megajoule for 1 tonn) to decompose to CaO and CO2… producing CO2
4-…now you propose to use this CaO to trap some new CO2 on water… some CO2 that will be less than you’ve already spent!!!

First problem: what you have been doing is get free one CO2 molecule to absorb another CO2 molecule… not so smart…
Second problem: In order to decompose CaCO3 you’ll have to spend 1760 MJ or energy per 1 tonn of CaCO3, the equivalent you might produce burning 53 kg of carbon and producing 196 kg of CO2… all of that to trap 440 kg of CO2… and I didn’t count the energy needed for heating and all other operations!!!

Short: you are proposing to take a substance, spend a lot of energy (and produce a lot of CO2) to extract its CO2 and send it into the atmosphere so that you’ll be able to re-trap some of the CO2 you have just been producing… on thermodynamics, it doesn’t make sense…

Alberto

Ps: as you wanted numbers…
1-Energy needed to calcinate CaCO3: 176 Kjoule/100g CaCO3, equivalent to producing AT LEAST 19,6 g of CO2; heating CaCO3 to 900°C: 6 MJoule/100g CaCO3 theoric (based zero loss efficiency)
2-CO2 generated during the production of lime: 44g CO2 from 100g CaCO3 decomposition, 19.6 g CO2 due to you need to give energy to decompose 100g CaCO3… at least 180g CO2 for heating of 100g CaCO3 based on Carbon rich fuel
3-CaCO3 calcination is a process that is thermodynamically possible only at very high temperature (900°C or more); no way of proceeding without heating.

Jem Cooper says: February 9th, 2010

Alberto,
The plan only makes sense if you capture and sequester the carbon dioxide produced in the calcination step.

Adam Pelling-Deeves says: April 21st, 2010

Hi,

I’m a freelance video editor and producer based in Oxford and I thought it would be a good idea to introduce myself in case my help in video work is something that would be of any use to you in the future.

Working predominantly in the world of corporate video, I’ve created videos for training, conferencing, marketing and web content for a wide variety of clients since 1997.

I’m currently located just a couple of hundred meters from Oxford station and have my own Final Cut Studio suite. For more information or to have a look at some of my work you can visit http://www.adampellingdeeves.com

Thanks,
Adam

Jeremy says: July 11th, 2010

Re: calcium oxide to precipitate calcium carbonate to sequester carbon dioxide

Dear Dr. Kruger,

I was wondering if I could ask you about a project I am designing for carbon sequestration. I am currently a rising junior in high school in Pennsylvania, USA. This summer I am participating in an environmental science program at the University of Pennsylvania for high school students. Seven students are in the program, and as part of the program we are given the opportunity to design our own laboratory research project. We have three weeks to perform this experiment, but can continue working on it during the year if we would like.

I have been reading about carbon sequestration, and have been particularly interested in the difficulty in getting rid of the sequestered carbon. It occurred to me that if factory exhaust fumes can be percolated through water, it may be possible to precipitate out the CO2 as calcium carbonate (similar to what shellfish slowly do to create limestone). This calcium carbonate could then be used commercially for cement, paper, etc. As a result, CO2 would be sequestered and then “disposed of” as a useful material.

I was very excited to read about your approach to use calcium carbonate precipitation to reduce ocean acidification. Upon reading your methods from the web, it wasn’t clear to me how easy it would be to use the calcium oxide to react with the CO2 in water to precipitate out the calcium carbonate. I was therefore wondering if you could be so kind to give me a better understanding of this process, and if it might be something I could do in a laboratory.

As I only have a short time to do this experiment, and I am just a high school student, I was wondering if I could propose to you my experimental design to see if you think if it makes sense. If not, I surely would appreciate any insights you might have for a better experiment.

At present, my experimental design would be as follows: My CO2 source would be dry ice. I would place the dry ice in a container of water (the pH, salinity, etc. would be as per your recommendations). I would then add commercially available calcium oxide (again, as per your recommendations). I have read about the heat and fumes generated from this process, and would be able to work in a hood. I would then quantitate the amount of calcium carbonate generated from the amount of calcium oxide and CO2 used. I understand from your article that although CO2 and energy would also be needed to create the calcium oxide that I commercially buy (or create as per your process), the net CO2 sequestration would still be positive.

I’m sure you are very busy, so I can certainly understand if you don’t have time to help me. However, if you could be so kind to guide me as to the potential of my idea, and the feasibility of my experimental design, I would be greatly appreciative. In addition, if you have any other ideas as to how a high school student like myself could perform a useful experiment to explore this important topic I would be very thankful.

Thank you for your help,
Jeremy

Jeremy says: July 11th, 2010

I made a typo when giving my email address. Attached is the correct email addresss.
Thank you,
Jeremy

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