CO2 sequestration

CO2 sequestration is the broad label that is applied to technologies aimed at either (1) removing CO2 from Earth’s atmosphere or (2) preventing this greenhouse gas from entering the atmosphere. At the EEGL, our work on CO2 sequestration focuses on mineral carbonation, whereby CO2 is trapped and stored over geologic timescales within the crystal structures of carbonate minerals.

We are working on several mineral carbonation projects.

Mineral carbonation in mine tailings. The mineral waste from some mines naturally reacts with CO2 in the atmosphere to form carbonate minerals. These minerals provide effective long-term traps for CO2 and we have shown that their formation offsets ~11% of the annual greenhouse gas emissions from at least one operating mine (Wilson et al. 2014). We are working with government and mining companies on novel (bio)geochemical strategies to enhance the rate of carbonation in mine tailings with the long-term goal of enabling carbon-neutral mining. We are developing new technologies to measure CO2 sequestration in minerals, such as the use of portable X-ray diffraction for field-based crystallographic accounting (Turvey et al. 2017). Our team at the University of Alberta is particularly focused on developing the technical basis for quantitatively mapping coupled fluxes of carbon and metals on the > 1 km2 scale to permit accounting of anthropogenic processes on global biogeochemical cycles (e.g., Turvey et al., 2018a, Turvey et al., 2018b).

Lakes that sequester CO2. We are exploring how Mg-carbonate sediments form in unique lakes in Australia and western Canada. Lakes that produce anhydrous Mg-carbonate minerals, such as dolomite and magnesite, represent important natural laboratories for studying CO2 sequestration. Furthermore, they are models for geoengineered landscapes that could be used to mineralize industrial and atmospheric CO2 (Power et al. 2009). Production of Mg-carbonate minerals is commonly mediated by microbial communities but also depends strongly upon initial aqueous geochemical conditions. We are working to forensically decipher and emulate these conditions to develop faster, more energy-efficient strategies for trapping CO2 in the most stable possible minerals.

Mapping carbonate mineral behaviour. The stability of CO2 storage in carbonate minerals depends strongly upon the hydration states of the host minerals; the lower the hydration state the more thermodynamically stable the mineral and the more stable the trapping. Our team is currently working on mapping the stability and environmental behaviour of these minerals (e.g., Morgan et al., 2015, Hamilton et al. 2016). This information can be used to identify low energy pathways to enhance stability of CO2 storage in minerals and to ensure storage of mineral carbonates under optimal environmental conditions.