Marine basalt complexes within reach of Europe – quo vadis?

Abstract

Carbon Dioxide Removal (CDR) approaches are essential to achieve the Paris 2015 global warming targets, as emphasized by the Intergovernmental Panel on Climate Change (IPCC) in their reports from 2021 onwards. With European legislation and ethical constraints in mind, a desirable approach to contribute to meeting ambitious climate goals would require to find safe, effective and sustainable storage sites on European territory, e.g. to avoid additional CO2 footprint for transportation or other processing steps needed. Given that the (admittedly substantial) storage capacity of Mesozoic sandstones forming the continental socket of wider parts of Europe (with a potential to host 270 Gt of carbon dioxide) has been widely accepted, there still remain doubts that these deep, warm reservoirs are the ideal place for storage of supercritical CO2, in particular since the overburden strata are heavily fractured and far less impermeable than what would be ideal and safe – let alone the elevated temperatures in several kilometres where Buntsandstein formations encounter conditions where carbon dioxide remains in its supercritical state for geological times. In contrast, oceanic basalts have been demonstrated to host CO2 both as structural (pore volume) and mineral (precipitation as carbonate minerals) traps in a sustainable manner. In large water depth the CO2 is stable as pure carbon dioxide, and when dissolved in seawater, the carbonated equivalent is heavier than pure seawater and unlikely to escape. With that in mind various European regional scenarios have been (re-)visited in order to assess feasibility and potential of storage. We have focused on the North Atlantic Volcanic Province (NAVP) with an estimated volume of extrusives close to 1.8 Mill. km3. The NAVP comprises various mafic and ultramafic regions between Iceland, the UK and Norway, including ocean crust, vesicular basalt and other igneous rock originating from the opening of this part of the Atlantic Ocean. We identified various corridors using ArcGIS Pro in combination with the Carbfix Mineral Storage Atlas and quantified the storage potential and associated cost in case CDR was to be carried out in these areas. Despite the large uncertainty in such numbers, the study serves to compare (among others) the Vøring and Møre basins, the Aegir ridge, Shetland and Faroer islands and neighbouring facies, and the Rockall basin and ridge. Farther from industrial centres we also investigated Iceland and the Reykjanes ridge. The work carried out is part of the AIMS3 project as part of the research mission CDRmare (www.cdrmare.de).