UNCERTAINTY IN CO2 STORAGE COST AND RESOURCE ESTIMATES

Carbon capture from stationary sources and geological storage of anthropogenic carbon dioxide (CO₂) is an important option to include in strategies for the mitigation of greenhouse gas (GHG) emissions. However, the potential costs of commercial-scale CO₂ storage are not well constrained, stemming from the inherent uncertainty in current geologic storage resource estimates coupled with a lack of detailed estimates of the infrastructure needed to access those resources. The storage resource estimates are highly dependent on storage efficiency values, which are calculated based on ranges of geological and physical parameters. If dynamic factors (such as variability of storage efficiency and injection rates), reservoir pressure limitations, CO₂ migration boundaries, consideration of closed or semi-closed saline reservoir systems, and other possible constraints on recent estimates of the technically accessible CO₂ storage resource (TASR) in the United States are accounted for, it is possible that only a fraction of the estimated TASR could actually be available without incurring significant additional costs. Although high-level assessments of the TASR typically assume that any issues with reservoir pressure buildup as a result of CO₂ injection will be mitigated by reservoir pressure management, most estimates of the costs of CO₂ storage do not include the costs of pressure management. Production of brines could be essential to increasing the dynamic storage capacity of reservoirs that will be targeted for CO₂ storage to approach volumetric storage capacity levels (IEAGHG, 2014), but including the costs of this critical method of reservoir pressure management could increase current estimates of the costs of CO₂ storage (e.g., Dahowski and others, 2011; NETL, 2014) by two times, or more (Harto and Veil, 2011). To the extent that uncertainty in the availability and cost of CO₂ storage contributes to uncertainty in the costs of the entire process of carbon capture and storage, it could be a factor in delaying investment into upstream carbon-capture projects (Laughton and others, 2008). It may be useful to have basin-wide (or greater) estimates of geologic storage capacity broken down into economic feasibility classes according to the total costs of CO₂ storage, including the expected costs of pressure management.