Techno-economic evaluation of indirect carbonation for CO2 emissions capture in cement industry: A system dynamics approach

Abstract

CO2 emissions in the cement industry account for about 8% of the total CO2 emissions worldwide. They mainly originate from limestone calcination and fossil fuel combustion in clinker production. To avoid the 2 °C increase in global temperature compared with the pre-industrial global temperature, which was proposed in the COP21 agreement in 2015, the cement industry should reduce CO2 emissions by 24%. Thus, this study evaluates an indirect carbonation CO2 capture and utilization technology for CO2 emissions abatement in the clinker production. The indirect carbonation process was assessed using different hydroxides (Na, Ba, and Ca) as absorbent precursors. Technical evaluation shows that the carbonation process using Na and Ba hydroxides was feasible between 50 and 70 °C, with CO2 capture efficiencies of 98% and 65%, respectively. On the contrary, the Ca-based process only obtained an efficiency of 0.5% due to the low solubility of Ca(OH)2 in water, resulting in technical impracticality. The estimated costs of CO2 capture for Na and Ba processes were assessed at 65 and 140 USD/t CO2, respectively. Moreover, the economic impact of implementing the CO2 capture carbonation technology in a cement plant and the effect of market and governmental conditions on the overall cement plant cashflow were analyzed by integrating technical results and economic evaluation in a system dynamics model. This model was developed to appraise the overall economic impact of CO2 capture on a referential cement plant profits under different market scenarios and a CO2 tax economic policy. System dynamics results showed that market factors, such as the carbonate demand, limit the CO2 capture potential of the indirect carbonation technology. Moreover, it was noticed that the implementation of the NaOH and Ba(OH)2 carbonation technologies reduces cement plant profits by 55% and 5%, respectively, when CO2 emissions were reduced by 65% in both scenarios. Furthermore, the application of a CO2 tax between 20 and 80 USD/t CO2 emitted will encourage the implementation of CO2 capture technologies, with the aim to reduce its emissions by 24% via cement plants.