Hybrid life cycle assessment of steel production with carbon capture and storage
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Among several Green house gases, CO2 is a main contributor and accounts for about 60% of the greenhouse effect because of its huge emission amount. The iron and steel sector has showed one of the largest energy intensity among manufacturing sectors. 31% of CO2 emission in the industrial sectors is caused by the production of iron and steel and the amount of CO2 emission corresponds to nearly 6-10% of global CO2 emission. The potential of CCS in the industrial sectors is considered to be significant to mitigate CO2 emission to the atmosphere. IEA has estimated that, in a scenario to halve global greenhouse gas (GHG) emissions in 2050 compared to 2007 level, nearly half of all CCS deployed (up to more than 10Gt/yr) would be in industrial processes. In the study, the environmental performance of CCS deployment in blast furnace (BF), top gas recycling blast furnace (TGRBF) and COREX processes which are technologies for producing pig iron has been evaluated by Hybrid life cycle assessment (LCA). In terms of BF with a capture unit of chemical absorption by MEA solvent, expect for the GWP, other environmental impacts showed increases. As for TGRBF with PSA (pressure swing adsorption), while GWP and TAP decreased compared to TGRBF without CCS, the other environmental impacts were increased. COREX with physical absorption by Selexol solvent showed same trend with the BF+MEA. The net reduction of GWP was 26% in the BF+MEA, 31% in the TGRBF+PSA, and 48% in the COREX+Selexol when performing CCS technologies into pig iron production in life cycle boundary. When it comes to the change range of the environmental impacts, the BF+MEA presented the higher increases on overall environmental impact categories except for GWP than other technologies with CCS. Regardless of CCS implementation, the COREX technology showed the highest benefits for most environmental impact factors aside from IRP and POFP. Overall, additional energy requirements by CO2 capture unit in all technologies for pig iron production mainly contributed increases in terms of most environmental impacts. The impacts of transport and storage, and other materials such as solvent and sorbent production were negligible.This study has shown that hybrid LCA method is a helpful tool to support the discussion about environmental effects with respect to CCS technologies depended on different ironmaking technologies.