Mineralization of carbon dioxide: experimental research and techno-economic comparative analysis

This thesis investigates the experimental and technical aspects of converting carbon dioxide (CO2) into calcium carbonate, with a focus on the necessity of purifying CO2 before the mineralization process. The first part concerns an experimental setup, involving 12 different trials, varying the concentrations of calcium and CO2, starting from pure calcium oxide (CaO). Furthermore, in the second part, a techno economic comparative analysis (TEA) was conducted. Based on literature dataset, two different calcium- containing feedstock materials were chosen, respectively wollastonite, a naturally occurring mineral, and steel slag, a disposal product of slag industry. These analyses were conducted for a mixed plastic waste gasification process to produce hydrogen as the base case. Successively, to the base case were added five CO2 removal processes scenarios, with and without the presence of mono-ethanol amine capture for purification. For each of the six scenarios were evaluated the levelized cost of hydrogen (LCOH), the levelized cost of capture (LCOC), and direct and indirect greenhouse gases (GHGs) emissions. The experimental section results demonstrated that higher capture efficiencies were achieved with increased calcium and decreased CO2 concentrations. Moreover, TEA demonstrate that scenario 3.2, which involves diluted CO2 stream for mineralization, was the most cost-effective and environmentally friendly option. Sensitivity analyses further supported these findings. In summary, this study confirms the viability of using industrial waste as calcium sources in the CO2 mineralization process, offering a dual benefit of waste reduction and emissions reduction via carbon capture. Future research could be focused on the scalability of these findings and explore more comprehensive utilization of diluted CO2 streams, potentially opening new avenues for industrial applications and environmental conservation.