(206a) Toward a Risk-Based Approach to Justify for Closure at Geologic Carbon Storage Sites

To enable full-scale implementation of geologic carbon storage(GCS) technology stakeholders must have confidence in the ability of GCS sites to safely store large volumes of CO₂ out of the atmosphere for long periods of time, while also protecting human health and the environment. Post-injection site care at GCS sites requires operators to demonstrate non-endangerment of underground sources of drinking water before site closure can be justified. In the study presented here numerical simulation and risk assessment results from a set of hypothetical, but realistic geologic carbon storage sites are considered. These results are used as the basis for defining a science-based, quantitative workflow to justify closure at GCS sites. Using monitoring observations to update performance predictions through the period of active injection period can substantially reduce uncertainties in storage system behavior, that driving force for leakage decreases after injection operations stop, and that in storage sites with reservoirs “stable” it should be safe to reduce post-injection site care requirements. This workflow represents a defensible, science-based approach to evaluate the robustness of GCS site integrity amidst remaining uncertainty, and to justify closure decisions to ensure the long-term protection of groundwater resources.