Creating a toolkit for in-situ CO2 mineralisation in basaltic rocks

Project duration: July 2023–June 2026

Project lead

Team

Ben Clennell, Junfang Zhang and Healther Sheldon.

Opportunity

Transitioning to net zero emissions requires increased investment in new technologies to capture, store and transform CO₂. Australia is a leader in conventional CO₂ storage in sandstone reservoirs but investment in in-situ CO₂ mineralisation in basaltic (mafic and ultramafic) rocks is lacking.

Basaltic rocks are widespread in Australia – in outcrops, shallow underground reservoirs and mine tailings – and recent research from the US and Europe has shown that CO₂ mineralisation in these types of rocks has a promising future. The major advantages of the method are that it’s fast and has zero risk of CO₂ leakage.

The process relies on natural reactions between CO₂ and the highly reactive basaltic rocks, which results in carbonate precipitation that locks CO₂ into solid minerals. But there are questions to be answered, such as identifying the right basaltic rocks (mineral composition, porosity and permeability) and the correct physiochemical conditions (temperature, pressure and brine composition) to achieve optimum outcomes. As the national science agency, CSIRO has the capability to lead research in in-situ CO₂ mineralisation in basaltic rocks. What’s needed is increased investment to unravel the geochemical mechanisms of CO₂ mineralisation, and tackle the engineering challenges of field-scale operations. Filling these knowledge gaps would bring us a step closer to making CO₂ mineralisation a realistic proposition for carbon dioxide removal, and also provide opportunities in a broad range of other research areas and potential commercialisation pathways.

Goal

The goal of the project is to trace the in-situ CO₂ mineralisation process in basaltic rocks, and propose a method to overcome its engineering challenges that can be extended to different geochemical and biogeochemical reactions in underground reservoirs. This would provide a toolkit of methods that can be applied to various profitable underground engineering scenarios, such as hydrogen storage. We’ll use geochemical modelling, together with rock characterisation and advanced experiments to gain a fundamental understanding of the geochemical reactions between CO₂ and basaltic rocks under varying conditions. We’ll evaluate the potential and kinetics of in-situ mineralisation, determine the reactive flow pattern and characterise the petrophysical changes that occur in the process. This will enable us to identify the most promising minerals for carbon mineralisation, and determine the mineralisation potential of different basaltic rock reservoirs throughout Australia.

Barriers

Currently, the knowledge gaps and engineering challenges involved in CO₂ mineralisation in basaltic rocks create a barrier to advancing and commercialising the technology at any large scale. Tackling these issues is essential to developing the robust methods required to make CO₂ mineralisation a reality. There’s also a risk that coding for the model required to understand the flow and mixing effects of CO₂ mineralisation in basaltic rocks (reactive transport model) may fail. In this case, we’ll switch to open-source simulation libraries and adapt them to our project.

References

Gunnarsson, I., Aradóttir, E. S., Oelkers, E. H., Clark, D. E., Arnarson, M. Þ., Sigfússon, B., … & Gíslason, S. R. (2018). The rapid and cost-effective capture and subsurface mineral storage of carbon and sulfur at the CarbFix2 site. International Journal of Greenhouse Gas Control, 79, 117-126.

Pogge von Strandmann, P. A., Burton, K. W., Snæbjörnsdóttir, S. O., Sigfússon, B., Aradóttir, E. S., Gunnarsson, I., … & Gislason, S. R. (2019). Rapid CO2 mineralisation into calcite at the CarbFix storage site quantified using calcium isotopes. Nature communications, 10(1), 1983.