The North German Basin (NGB) is known for its capacity for geological storage applications. However, due to limited data availability, the data first needs to be collected from different sources and further compilation and processing is needed. This study's primary step is to compile and refine public data, fostering transparency for further scientific exploration. The comprehensive database encompasses five key aspects: geological features (e.g., reservoir thickness), litho-mineralogical characteristics, petrophysical properties (e.g., porosity), surface and risk factors (e.g., fault zones), and DAC-related considerations (e.g., geothermal energy availability).
The secondary step involves adapting and validating a holistic ranking methodology for evaluating sites suitable for direct air capture (DAC) technology in the NGB region. This method incorporates ten distinct criteria for initial site screening and selection. The criteria are divided into five classes and assigned scores based on quantitative or qualitative assessments. Then weighting factors were applied to quantify the relative importance of each criterion. They are determined by analytical hierarchy analysis method, which leveraging pair-wise comparisons to minimize inconsistencies and mitigate bias in expert opinions from a broad research background.
The method is tested on the 91 identified potential sites for underground CO2 storage, with 4 offshore North Sea traps identified for their favorable geological characteristics and 2 other onshore sites, a gas field in the west of Bremen and a saline aquifer in the north-east of Berlin. Future site-specific studies should be carried out on these four traps.