Project title: TARGETing crystallization for enhanced Carbon Capture & Storage (TARGET-CCS)
Researcher: Niamh Faulkner
The purpose of this research is to understand the kinetics and mechanisms of aluminium carbonate in order to target the synthesis dawsonite (NaAlCO3(OH)2) to maximise the amount of stored carbon during carbon capture and storage (CCS) processes. In depth knowledge of the aluminium carbonate system is needed to understand the geochemical conditions under which dawsonite forms and how it transforms to other non-C-bearing minerals. Controlling the formation of dawsonite during basalt CCS at (near)-ambient temperatures will maximize its capacity to store CO2. This research is important as it will further the field of climate change mitigation which is one of the biggest threats that humanity is currently facing. The world is currently 1°C warmer than preindustrial levels, and unless significant progress is made towards reducing the amount of CO2 in the atmosphere, the global average temperature will continue to rise to above 2°C by 2050 according to the latest International Panel for Climate Change (IPCC) report. The IPCC have highlighted the key role of Carbon Capture and Storage (CCS) has to ensure that temperatures remain within 2°C warming.
• CCS via mineral trapping is an ideal method for long-term storage of C underground. However, these methods are not easy because of the complexity of the geological environment and the water composition.
• We do not have an in-depth mechanistic understanding of how carbonate minerals form and how specific factors (e.g., temperature, pressure, supersaturation, foreign ions) affect their kinetics of formation. If we can understand the role of all these factors in CCS, it would be easier to control the formation of C-bearing minerals and therefore improve CCS methods.
• One of the most abundant elements in basaltic rocks is Al, besides Si, Ca, Na, K, Mg, Fe. This PhD focuses on the role of Al in CCS from two points of view:
o Effect of Al during CCS processes in which Ca/Mg carbonates (calcite, aragonite, dolomite, magnesite) form.
o Effect of Al during CCS processes in which Al-bearing carbonates (dawsonite) form.
• By understanding the role of Al in these reactions and the mechanisms by which these carbonates form, as well as their kinetics of formation, we could target the formation of C-bearing minerals (dawsonite) during field-based or industry-based CCS processes.
The aims of TARGET-CCS are to address two central questions: a) Can we develop a method to enhance the crystallisation of dawsonite in basaltic rocks at (near)- ambient conditions to improve CCS efficiency and lower its cost? b) Can we develop a robust methodology for stabilising dawsonite using (in)organics in natural CO2 reservoirs and prevent its transformation to non-C minerals at low CO2 pressures? To address these questions TARGET-CCS will study the in situ and real-time crystallisation of dawsonite under a range of environmental conditions using a combination of conventional laboratory (spectroscopic, microscopic, solid-state) techniques and synchrotron-based diffraction and scattering. These include small- and wide-angle X-ray scattering (SAXS/WAXS) and pair distributing function (PDF) at Diamond Light Source (UK). Using a solution-based nucleation and growth approach we will study the mechanisms and energetics of dawsonite nucleation, growth and transformation. This method will allow a faster crystallisation rate compared to CO2 reservoir conditions, where the dissolution rates of minerals such as albite (Al3+ and Na+ source) are too slow to allow a comprehensive mechanistic study of dawsonite crystallisation. TARGET-CCS will also assess the impact of environmental factors (i.e., pH, temperature, pressure, concentrations of foreign ions like Mg2+ and Ca2+) on dawsonite crystallisation and transformation to non-C bearing minerals.