Over the years, the cement industry has utilized the above measures to some degree to primarily improve its operations and reduce costs of supplying cement. In doing so, CO2 emission reductions have also taken place. While further emission reductions with broader use of above measures should be possible, mitigation measures utilizing CCS, when available, will be able to provide substantial reductions in future CO2 emissions. Three factors make the case for utilizing carbon capture technologies at cement plants more compelling: (1) cement plants generally are relatively large point sources of emissions, (2) the CO2 concentration in the flue gas of a cement plant is relatively high (about 25% on a molar basis), and (3) more than 50% of the CO2 emissions result from limestone calcination. The first two of these factors relate to the cost-effectiveness of CO2 capture, while the third factor speaks to the potential use of alternative raw material formulations (e.g., replacing a fraction of limestone with blast furnace slag) to reduce CO2 generation, thereby reducing capture requirements and associated costs.
Two CO2 capture technologies applicable to cement plants are: (1) post-combustion capture in which CO2 is scrubbed from the flue gas, and then compressed and transported to the sequestration site; and (2) oxy-fuel combustion in which fuel is combusted with oxygen, instead of air, to generate a concentrated stream of CO2, which can then be compressed and transported to the sequestration site. A comprehensive coverage of these measures is provided in IEA . Development of these technologies for power plants is ongoing. It is expected that the controls developed for power plants will be translatable to other industrial sectors, including cement manufacturing. Current indications are that CCS is not likely to be available for the cement industry before 2020 [4, 37].
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