The US has recently made a substantial commitment to solving the climate crisis via the bipartisan Infrastructure Investment and Jobs Act of 2021. A key component of that effort is carbon capture and storage (CCS), a scalable and technologically viable approach to sequester carbon dioxide (CO2) in the subsurface, and thus reduce the build-up of CO2 in the atmosphere. Simultaneously, the rapid development of direct air capture (DAC) technology is driving further interest in CCS for long-term storage of CO2 captured via these new technologies. 
CCS has been successfully demonstrated in a number of projects around the world and is poised to play an important role in getting to zero-emissions in the short term, and to negative emissions in the medium- to long-term. All current pathways that limit global warming to 1.5°C, with limited or no overshoot, project the use of carbon dioxide removal with CCS on the order of 100–1000 GtCO2 over the 21st century. In typical CCS applications, supercritical CO2 is injected to depths such that, due to reservoir pressure, the CO2 density is three orders of magnitude greater than at ambient pressure, thus utilizing storage volume more efficiently. Containment of a buoyant supercritical CO2 plume typically requires a low-permeability cap rock that is uncompromised by faults or abandoned exploration wells. By maximizing the fraction of CO2 that is stored via a mechanism called capillary trapping, the likelihood of success increases significantly (compared to reliance on an uncompromised cap rock) and allows for effective and safe storage of CO2. 

This lecture will introduce the concepts of DAC, CCS, and capillary trapping, and describe some of the technical, economic, and political challenges of securely and effectively storing as much CO2 as possible in the subsurface.

Dorthe Wildenschild is a professor in the School of Chemical, Biological, and Environmental Engineering. She holds M.S and Ph.D. degrees in Civil and Environmental Engineering from Danish Technical University. Her research focuses on flow and transport in porous media, with the goal of answering questions related to subsurface water pollution and energy-related storage challenges. Recent work includes optimization of geologic storage of anthropogenic carbon dioxide; colloid-facilitated transport of contaminants in groundwater; microbial enhanced oil recovery; and investigations in support of more effective groundwater remediation techniques.