Cement productions are considered to be doubly carbon-intensive because emissions come from both energy combustion and calcination chemical reaction. The cement industrial process emission from calcination chemical reaction account for 5% of global carbon dioxide from energy and all industrial emissions processes. Attention has been paid to quantify the emission amount during cement production. However, the natural reversal of the process - carbonation - has received little attention in carbon cycle studies.
An international team led by XI Fengming from Institute of Applied Ecology of Chinese Academy of Sciences has found that over time, the widely used building materials uptake 43% of the carbon dioxide emitted during cement industrial process. Scientists use the term sink to describe a feature like a forest or ocean that takes carbon dioxide out of the atmosphere and permanently tucks it away so it can no longer contribute to climate change. In addition to carbon sink from ecosystem, the alkaline cement material is one of most important carbon sink.
Researchers used new and existing data on cement materials during cement service life, demolition and secondary use of concrete waste to estimate regional and global CO2 uptake between 1930 and 2013, and an analytical model describing carbonation chemistry.
The findings showed that carbonation of cement materials over their life cycle represents a large and growing net sink of CO2, increasing from 0.10 GtC yr-1 in 1998 to 0.25 GtC yr-1 in 2013. In total, more than 76 billion tons of cement were produced around the world from 1930 to 2013 with four billion tons produced in 2013 alone. A cumulative amount of 4.5 GtC has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the CO2 emissions from production of cement over the same period, not including emissions associated with fossil use during cement production.
“The global carbon uptake by cement carbonation is large and substantial, which give a new perspective for missing sink mystery and the carbon sink from human activities have not revealed comprehensively, the new technologies of carbon capture and storage using the cement wastes should be developed for climate change mitigation.” said XI Fengming.
The study entitled “Substantial global carbon uptake by cement carbonation” has been published in Nature Geoscience.
Full text URL: http://www.nature.com/ngeo/journal/v9/n12/full/ngeo2840.html#ref1
Abstract: Calcination of carbonate rocks during the manufacture of cement produced 5% of global CO2 emissions from all industrial process and fossil-fuel combustion in 20131, 2. Considerable attention has been paid to quantifying these industrial process emissions from cement production2, 3, but the natural reversal of the process—carbonation—has received little attention in carbon cycle studies. Here, we use new and existing data on cement materials during cement service life, demolition, and secondary use of concrete waste to estimate regional and global CO2 uptake between 1930 and 2013 using an analytical model describing carbonation chemistry. We find that carbonation of cement materials over their life cycle represents a large and growing net sink of CO2, increasing from 0.10 GtC yr−1 in 1998 to 0.25 GtC yr−1 in 2013. In total, we estimate that a cumulative amount of 4.5 GtC has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the CO2 emissions from production of cement over the same period, not including emissions associated with fossil use during cement production. We conclude that carbonation of cement products represents a substantial carbon sink that is not currently considered in emissions inventories1, 3, 4.
Publication Name: Xi Fengming, Steven J.Davis, Philippe Ciais, Douqlas Crawford-Brown, Guan Dabo, Claus Pade, Shi Tiemao, Mark Syddall, Lv Jie, Ji Lanzhu, Bing Longfei, Wang Jiaoyue, Wei Wei, Keun-Hyeok Yang, Björn Lagerblad, Isabel Galan, Carmen Andrade, Zhang Ying, Liu Zhu.
Email: xifengming@iae.ac.cn.
