The Role of Mineral Carbonation in Carbon Capture

Abstract

Mineral carbonation takes place through the reaction of CO2 with an alkalinity source that includes divalent cations such as calcium (Ca2 +) andmagnesium (Mg2 +) as well as hydroxyl anions to form stable carbonate minerals. Similar to algae-based (Chap. 7) and electrochemical CO2 reduction (Chap. 8) processes, mineral carbonation has the potential to couple the capture with the long-term storage of CO2. Although most studies of mineral carbonation to date have focused on the carbonation of a pure CO2 gas (i.e., assuming a previous capture step), CCS in a single-step mineral carbonation process may one day be possible. Therefore, it is important to consider this concept in the broader portfolio of CO2 capture technologies. Figure 9.1 shows a possible mineral carbonation stream in which an alkalinity source reacts with CO2 to form mineral carbonate. Energy requirements include thermal or mechanical treatment of the alkalinity source to improve its reactivity toward mineral carbonation. Determining the end use of the mineral carbonate may provide an upper limit on how much energy one is willing to spend on the carbonation process.