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Cement releases CO2 as part of it's chemical curing process. It contributes to about 8% of worldwide emissions. Another industry where CO2 as a chemical byprod
by Valgrim 7y ago
Cement releases CO2 as part of it's chemical curing process. It contributes to about 8% of worldwide emissions.
Another industry where CO2 as a chemical byproduct is vented at a massive scale in the atmosphere is with the steel industry.
Both are good targets for carbon capture at the source.
- hannob 7y ago> Cement releases CO2 as part of it's chemical curing process. It contributes to about 8% of worldwide emissions. Just to nitpick here, but I think this is crucial to understand: 8% is more plausibly a number for the total emissions of cement, including energy emissions. The chemical emissions are more in the range of 4%.
- tonyedgecombe 7y agoI'm not sure it would even be practical to capture the carbon emitted during the curing process as this is happening at it's final destination rather than during manufacture.
- ivanhoe 7y agoFrom what I've read about carbon-negative cement, idea is not to capture the carbon released during curing, but to make concrete that later, over years, chemically reacts and captures the carbon from the air. Because concrete is porous to the depth of 20+ inches, it has a very large surface that can slowly extract more CO2 from air than it initially had released.
- labawi 7y agoAFAIK the usual cement types do not release CO₂ during curing, though a significant amount of CO₂ is released from the ingredients while baking. Sometimes the released CO₂ is reabsorbed when curing (lime). What type of cement are you talking about? Reference: http://matse1.matse.illinois.edu/concrete/prin.html http://matse1.matse.illinois.edu/concrete/prin.html
- ComputerGuru 7y agoThat’s not how CCS or net carbon works. CO2 is basically fungible. You can release it today in Australia and capture it yesterday or tomorrow in Canada to offset, it basically makes no appreciable difference.
- leoedin 7y agoI think the biggest reason for capturing at source is the concentration of the gas. Capturing CO2 when it's in atmosphere at 0.04% is much more energy intensive than capturing at source where concentrations could be many orders of magnitude higher.
- the8472 7y ago> Cement releases CO2 as part of it's chemical curing process. It contributes to about 8% of worldwide emissions. There are 2 sources of CO2 during cement manufacture. One is from the decomposition of lime, the other is from the energy production needed to make the process work. The latter could be avoided by electrical heating, a solar furnace or other renewable heat sources. The decomposition part can be compensated by newer cement chemistries that reabsorb most of the CO2 during the curing process. So there are alternatives, carbon capture is not the only solution.
- trickstra 7y agoCould you point me to any of the newer cement chemistries?
- the8472 7y agosilicate and magnesium oxide based ones. https://en.wikipedia.org/wiki/Sorel_cement https://en.wikipedia.org/wiki/Sorel_cement https://www.solidiatech.com/solutions.html https://www.solidiatech.com/solutions.html
- throw_14JAS 7y agoDo you roughly know the relative ratios of emission for the sources?
- pfdietz 7y agoCement releases CO2 when lime is made from limestone. The curing of cement absorbs CO2 (less than was released in making the lime).
- natch 7y agoOur local cement factory (huge, and one of the top polluters in California) burns coal on site as a source of heat. So there's that, too.