The potential for in-situ mineral carbonation in Ireland
Alexander, Jonathan
Alexander, Jonathan
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Identifiers
https://hdl.handle.net/10379/18216
https://doi.org/10.13025/18034
https://doi.org/10.13025/18034
Repository DOI
Publication Date
2024-06-14
Type
master thesis
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Abstract
Industrial decarbonisation, involving hard-to-abate sectors and key carbon dioxide removal (CDR) technologies, necessitates geological CO2 disposal/storage. Geological storage can be performed via solubility and hydrodynamic trapping in sedimentary basins, or alternatively via the novel approach of CO2 mineral trapping in mafic/ultramafic lithologies, known as in-situ mineral carbonation. Ireland currently lacks specific targets for the deployment of carbon capture and storage (CCS), or CDR technologies. By characterising the geological storage potential of CO2, government targets for CCS deployment will be more easily implemented. Therefore, this thesis involves mapping, screening, ranking, and characterising igneous lithologies in Ireland for CO2 storage via in-situ mineral carbonation. Mapping of the lithologies highlighted 29 groups of geological formations across Ireland, considered as candidate CO2 reservoirs for in-situ mineral carbonation. These geological formations were screened using several criteria covering mineralogical, structural, socioeconomic, and environmental conditions. The ranking process identified the Antrim Lava Group (ALG) flood basalts as the most suitable for mineral carbonation, given their proximity to major power plants in Northern Ireland and sufficient thickness for CO2 injection. The outcropping metagabbro of the Connemara Metagabbro-Gneiss Complex (MGC) emerged as the most promising candidate reservoir in the Republic of Ireland, potentially extending up to 10 km offshore and having high secondary permeability from Connemara metamorphism. The Dawros Peridotite intrusion, despite its small size, was also identified for further study due to its ultramafic composition. Petrology and energy dispersive X-Ray spectrometry (EDS) characterisation were performed for the geochemical characterisation of these three reservoirs. The ALG comprises large glomeroporphyritic forsterite within coarse-crystalline ophitic/sub-ophitic groundmass labradorite and augite, with secondary mineralisation of mostly Ca-rich zeolites. However, forsterite is often altered to iddingsite and variably to clay minerals. The MGC contains highly anorthic plagioclase and magnesiohornblende but shows variable phyllic and propylitic alteration to quartz-sericite-pyrite and epidote-chlorite-albite assemblages, respectively. Lastly, the Dawros Peridotite is altered from its ultramafic protolith to amphibole-serpentine-talc-carbonate facies, indicating serpentinisation and natural carbonation have occurred. Therefore, the methodologies applied to the three formations identify the appropriate mineralogy for mineral carbonation, but secondary alteration products, particularly phyllosilicates and zeolites, will also be incorporated into carbonation reactions where present.
Publisher
University of Galway
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International