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GSBN:Re: Cemento (% of total C02 emissions)



When we last had this discussion on GSBN, list members quoted several sources, which reported one ton of CO2 released per ton of cement. It is interesting to me that the Oak Ridge number is 25% higher than the figures that we found a few years ago.

At that time, no one was able to come up with any kind of average, best case or worst case numbers on the amount of CO2 released in other parts of cement use. The limestone must be mined, crushed, transported to the kilns, burned, ground, packaged, transported to the vendor, transported to the job site, installed and finished. I wish I had some idea of how much CO2 is released in these activities. There are many variables, but analyzing one average case would be informative. Would these factors together double the carbon impact of using Portland cement, compared to the calcining kiln process by itself? Or are these other steps in the process much less significant than the kiln process? If anyone has any insights or figures, I would love to hear about them.

Derek

Derek Roff
Language Learning Center
Ortega Hall 129, MSC03-2100
University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek@...

--On Thursday, July 5, 2007 10:45 AM +1200 Graeme North ecodesign@... wrote:

Combustion of fossil fuels to operate the rotary
kiln is the largest source: approximately 3/4
tons of CO2 per ton of cement. But the chemical
process of calcining limestone into lime in the cement kiln also produces
CO2:

CaCO 3 â CaO + CO 2 limestone â lime + carbon dioxide

This chemical process is responsible for roughly
1/2 ton of CO2 per ton of cement, according to
researchers at Oak Ridge National Laboratory.
Combining these two sources, for every ton of
cement produced, 1.25 tons of CO2 is released
into the atmosphere.



Derek Roff
Language Learning Center
Ortega Hall 129, MSC03-2100
University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek@...