U.S. GEOLOGICAL SURVEY NATIONAL ASSESSMENT OF GEOLOGIC CARBON DIOXIDE STORAGE RESOURCES

The U.S. Geological Survey (USGS) recently completed an evaluation of the technically accessible storage resource (TASR) for carbon dioxide (CO₂) for 36 sedimentary basins in the onshore areas and State waters of the United States. The TASR, an estimate of the geologic underground resource capacities that may be available for CO₂ injection and storage, is based on current geologic and hydrologic knowledge of the subsurface and current engineering practices. By using a geology-based probabilistic assessment methodology, the USGS obtained a mean estimate of approximately 3,000 metric gigatons (Gt) of subsurface CO₂ storage capacity that is technically accessible below onshore areas and State waters; this amount is more than 500 times the 2011 annual U.S. energy-related CO₂ emissions of 5.5 Gt estimated by the U.S. Energy Information Administration. The largest storage potential by far is in the Coastal Plains region, which accounts for 2,000 Gt, or 65 percent, of the national storage potential.

In 2007, the Energy Independence and Security Act (Public Law 110–140) directed the USGS to conduct a national assessment of geologic storage resources for CO₂ in consultation with the U.S. Environmental Protection Agency, the U.S. Department of Energy, and State geological surveys. The USGS developed a methodology to estimate storage resource potential in geologic formations in the United States, completed the assessment in 2012, and published the results in 2013 (see: http://pubs.usgs.gov/circ/1386/). The assessment considered factors that include reservoir depth, water salinity, and the occurrence of an overlying impermeable sealing unit. The goal of this project was to conduct an initial assessment of storage capacity on a regional basis, and the results are not intended for use in the evaluation of specific sites for potential CO₂ storage. Although geologic storage of CO₂ may be possible in some areas not assessed by the USGS, the SAUs identified in this assessment represent those areas within sedimentary basins that initially met the assessment criteria.