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 EGEL, our research is focused on carbon mineralisation, whereby CO2 is trapped and stored over geologic timescales within the crystal structures of carbonate minerals.

We are working on several carbon mineralisation projects with the support of the Australian Research Council, Carbon Management Canada and state government.

Mineral carbonation in mine tailings. Our team is working with colleagues at The University of Queensland and The University of British Columbia on field-scale trials of enhanced weathering and carbonation in ultramafic mine tailings. The mineral waste from some mines naturally reacts with CO2 in the atmosphere to form carbonate minerals. These minerals provide effective longterm 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 on novel biogeochemical strategies to enhance the rate of carbonation in mine tailings with the longterm goal of enabling carbon-neutral mining.

Lakes that sequester CO2. We are exploring how Mg-carbonate sediments form in unique Australian lakes. Lakes that produce 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 mineralise 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. 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.