Benchtop Visualization of Carbon Storage Processes

Abstract Geological carbon storage (GCS) is a key technology for reducing greenhouse gas emissions by injecting large volumes of carbon dioxide (CO2) into subsurface formations for long-term containment. Understanding and communicating CO2 flow behavior and storage mechanisms is essential to ensuring safe and effective storage as well as gaining stakeholder support. Physical models that visually demonstrate CO2 transport, trapping, and the influence of geological heterogeneity provide valuable insights into storage processes. These models highlight the importance of geological features, such as sealing formations, in maintaining secure storage. In addition to advancing scientific understanding, they serve as effective tools for public education, allowing both technical and non-technical audiences to observe CO2 storage dynamics in action. This direct observation approach improves communication, fosters greater awareness of CO2 storage as an emissions mitigation strategy, and ultimately supports public acceptance. This study develops a benchtop-scale, two-dimensional (2D) physical model (32 cm × 25 cm) to visualize CO2 migration and trapping in porous media. The methodology comprises model construction, sand preparation, pH-sensitive dye formulation, sand configuration, and CO2 injection experiments. Three analog stratigraphic configurations are used including a sealed homogeneous reservoir, an unsealed homogeneous reservoir, and a multilayer reservoir. Sand-packed formations are saturated with water containing pH-sensitive dyes, including a chemical indicator and a natural alternative derived from red cabbage anthocyanins. This approach allows clear visualization of CO2 dissolution within the aqueous phase. CO2 for the experiments is generated through natural degassing of carbonated beverages. Results show buoyancy-driven upward migration of CO2, followed by CO2 dissolution into water that increases fluid density and causes downward movement due to gravity. Comparisons among sealed, unsealed, and multilayer reservoirs clearly illustrate the critical role of caprock in storage security. Future work will explore more complex geological configurations, including sealing and open faults, to investigate structural influences on CO2 migration. Overall, this benchtop model enhances understanding of CO2 storage processes and serves as an accessible educational tool to demonstrate the safety and feasibility of geological carbon storage.