7.3.7 Carbon dioxide Capture and Storage (CCS), including oxy-fuel combustion
CCS involves generating a stream with a high concentration of CO2, then either storing it geologically, in the ocean, or in mineral carbonates, or using it for industrial purposes. The IPCC Special Report on CCS (IPCC, 2005b) provides a full description of this technology, including its potential application in industry. It also discusses industrial uses of CO2, including its temporary retention in beverages, which are small compared to total industrial emissions of CO2.
Large quantities of hydrogen are produced as feedstock for petroleum refining, and the production of ammonia and other chemicals. Hydrogen manufacture produces a CO2-rich by-product stream, which is a potential candidate for CCS technology. IPCC (2005b) estimated the representative cost of CO2 storage from hydrogen manufacture at 15 US$/tCO2 (55 US$/tC). Transport (250 km pipeline) injection and monitoring would add another 2 to 16 US$/tCO2 (7 to 60 US$/tC) to costs.
CO2 emissions from steel making are also a candidate for CCS technology. IEA (2006a) estimates that CCS could reduce CO2 emissions from blast furnaces and DRI (direct reduction iron) plants by about 0.1 GtCO2 (0.03 GtC) in 2030 at a cost of 20 to 30 US$/tCO2 (73 to 110 US$/tC). Smelt reduction also allow the integration of CCS into the production of iron. CCS has also been investigated for the cement industry. Anderson and Newell (2004) estimate that it is possible to reduce CO2 emissions by 65 to 70%, at costs of 50 to 250 US$/tCO2 (183–917 US$/tC). IEA (2006a) estimates the potential for this application at up to 0.25 GtCO2 (0.07 GtC) in 2030.
Oxy-fuel combustion can be used to produce a CO2-rich flue gas, suitable for CCS, from any combustion process. In the past, oxy-fuel combustion has been considered impractical because of its high flame temperature. However, Gross et al. (2003), report on the development of technology that allows oxy-fuel combustion to be used in industrial furnaces with conventional materials. Tests in an aluminium remelting furnace showed up to 73% reduction in natural gas use compared to a conventional air-natural gas furnace. When the energy required to produce oxygen is taken into account, overall energy saving is reduced to 50 to 60% (Jupiter Oxygen Corp., 2006). Lower but still impressive energy efficiency improvements have been obtained in other applications, up to 50% in steel remelting furnaces, up to 45% in small glass-making furnaces, and up to 15% in large glass-making furnaces (NRC, 2001). The technology has also been demonstrated using coal and waste oils as fuel. Since much less nitrogen is present in the combustion chamber, NOx emissions are very low, even without external control, and the system is compatible with integrated pollution removal technology for the control of mercury, sulphur and particulate emissions as well as CO2 (Ochs et al., 2005).
Industry does not currently use CCS as a mitigation option, because of its high cost. However, assuming that the R&D currently underway on lowering CCS cost is successful, application of this technology to industrial CO2 sources should begin before 2030 and be wide-spread after that date.