A geological investigation on bedrock suitability for mineral carbonation conducted in the south central part of Sweden

Abstract: Increasing global temperatures due to anthropogenic emissions of greenhouse gases is one of our times most dire and urgent challenges to overcome if we are to achieve a sustainable healthy planet. The primary way of accomplishing this is by reducing the amount of released greenhouse gases. However, a complementary measure that has been proposed by IPCC (UN, Intergovernmental Panel on Climate Change) to combat this challenge is the carbon dioxide removal technology bio-energy carbon capture and storage (BECCS). This study aims to investigate the suitability of areas located in the south-central part of Sweden for in-situ mineral carbonation, a relatively newly implemented method of permanently storing carbon dioxide in for instance Iceland. The project has been conducted in connection with the research project INSURANCE at Luleå University of Technology (LTU), which has as one of its main objectives to investigate the geological potential for land-based carbon dioxide storage in Sweden. Samples were taken from five different localities in the southern-central part of Sweden: Skutskär, Falun, Öje, Grums, and Åsensbruk. Fifteen representative field samples were then examined with optical microscopy, whole rock geochemistry analysis, scanning electron microscopy (SEM), and micro-XRF in order to characterize the area's bedrock with respect to their potential suitability for in-situ mineral carbonation. The investigations showed that the examined mafic rock units all contained various degrees of metamorphism and alteration, differing them from bedrock in which earlier in-situ mineral carbonation has been successfully tested (Carbfix, Iceland). However, the areas also generally contained considerable amounts of minerals with high Mg, Ca, and Fe ratios, indicating they have a potential for future in-situ mineral carbonation, however, further carbonation experiments are needed to better evaluate the potential.