A physical model for geological CO2 storage – Replacing misconceptions by visual explanation

Abstract

The public discussion on CCS is strongly affected by misconceptions that result from the lack of knowledge about the storage of CO2 in a geological environment deep underground. In this paper, a physical model is introduced which was developed to illustrate the migration of supercritical CO2 in porous rock, the structural trapping by a caprock, and the partial immobilization by the residual trapping mechanism in a way that is visually attractive, scientifically correct, and understandable for non-experts. The reservoir consists of a glass beads packing between two glass plates to represent a thin cut through an aquifer-caprock pair. The injected CO2 is represented by a substitute liquid that contains a fluorescent dye to enhance its visibility. A three-stage methodology was applied to scale the original process to the dimensions and conditions of the physical model realistically, including experiments and modeling at the macro- and pore-scale. Operation and cleaning of the physical model are automated in order to enable a single person to give consecutive presentations within a few minutes. Ancillary exhibits in the form of samples, videos, and posters allow a coherent introduction of CCS with a focus on storage. The comprehensive display with the physical model as the centerpiece has proven to be an effective tool for knowledge transfer from researchers to the general public. A video of a storage demonstration in the physical model and additional material are made accessible as supplementary material to the reader, who is thus enabled to utilize them for communication activities about geological CO2 storage.