The Lifetime of Carbon Capture and Storage as a Climate-change Mitigation Technology: How both Pressure and Migration Constrain CO2 Storage Capacity
Abstract
In Carbon Capture and Storage (CCS), CO2 is captured at large point sources like power plants and then stored away from the atmosphere in reservoirs like deep saline aquifers. There is currently much debate about how much CO2 it could store and long it could be extended into the future. Much of the confusion comes not from the economics of capture (which is indeed high), or the integration of capture-ready power plants into the energy system (which is indeed challenging), but from the geologic constraints on the injection and long-term storage of CO2. Fundamentally opposing viewpoints exist: from the view that storage capacity in deep saline aquifers is exceptionally large to the statement that ``CCS can never work'', which has generated multiple rebuttals. Here we address this controversy by formulating physics-based models of how much CO2 can be stored in deep saline aquifers and, in so doing, we reconcile and rationalize previous disparate results. We develop these models at the scale of an entire geologic basin since large quantities of CO2 will have to be stored to offset gigatons of emissions. Despite the many (necessary) simplifying assumptions, our models are based on the fluid dynamics of CO2 injection and migration, and they account for reservoir-specific rock and fluid properties. One of the fundamental results from our models is that storage capacity can be limited by both the ability of the formation to dissipate injection overpressures and by the migration of the injected CO2 underneath a sealing caprock. Thus, storage capacity must be understood as a dynamic quantity, which depends on the duration of injection, T. We calculate the storage capacity curve for eleven major deep saline aquifers in the US, and show that, if CO2 production from power generation continues to rise at recent rates, then CCS can store enough CO2 to stabilize emissions at current levels for at least 100 years. This result suggests that the large-scale implementation of CCS is a viable climate-change mitigation option in the US over the next century.his map shows the locations of the aquifers and their storage capacities for an injection period of 100 years. Capacities in boldface italics are constrained by pressure; otherwise, they are constrained by migration. The map also shows the ultimate CO2 footprints for those capacities, which correspond to the areas infiltrated by migrating, free-phase CO2 before it becomes completely trapped (from Szulczewski et al., 2012).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.B32C..04J
- Keywords:
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- 0428 BIOGEOSCIENCES / Carbon cycling;
- 1822 HYDROLOGY / Geomechanics;
- 1829 HYDROLOGY / Groundwater hydrology