USGS assessment identifies most promising areas by region
By Summit Voice
FRISCO — The U.S. Geological Survey says there’s potential to store more than 600 years (at 2011 emission rates) worth of carbon dioxide in various geologic formations around the country.
The first-ever detailed national geologic carbon sequestration assessment looked at all sedimentary basins, but 36 were assessed in detail because existing geologic conditions or the available data suggested only these 36 met the assessment’s minimum criteria.
“This USGS research is ground-breaking because it is the first realistic view of technically accessible carbon storage capacity in these basins,” said Secretary of the Interior Sally Jewell. “If enough of this capacity also proves to be environmentally and economically viable, then geologic carbon sequestration could help us reduce carbon dioxide emissions that contribute to climate change.”
- National Assessment of Geologic Carbon Dioxide Storage Resources—Detailed Results
- National Assessment of Geologic Carbon Dioxide Storage Resources—Data
The largest potential by far is in the Coastal Plains region, which accounts for 2,000 metric gigatons, or 65 percent, of the storage potential. Two other regions with significant storage capacity include the Alaska region and the Rocky Mountains and Northern Great Plains region.
According to the USGS, the identified areas could be accessed using today’s technology and pressurization and injection techniques. The most common method of geologic carbon storage involves pressurizing carbon dioxide into a liquid, and then injecting it into subsurface rock layers for long-term storage.
“Today’s assessment from the USGS is just the latest example of how the Department of the Interior is applying rigorous, peer-reviewed science to some of our nation’s most complex land- and resource-management challenges,” said Deputy Secretary David J. Hayes. “Nowhere is this more important than the issue of climate change, and today’s new research adds to the USGS’s groundbreaking work in biological carbon sequestration to better inform our carbon reduction efforts.”
Areas with groundwater sources that are considered freshwater by EPA standards were eliminated from consideration for carbon storage. Rock layers included in the assessment were limited to those determined to have sufficient natural seals to prevent CO2 from escaping. This assessment also focused only on rock layers located at depths at which CO2 would stay under sufficient pressure to remain liquid.
The study did not evaluate economic viability or accessibility due to land-management or regulatory restrictions for geologic carbon sequestration within these basins.
Overall, the study estimated a range of 2,400 to 3,700 metric gigatons of CO2 storage potential across the United States. For comparison, the U.S. Energy Information Administration estimates that, in 2011, the United States emitted 5.5 metric gigatons of energy-related CO2, while the global emissions of energy-related CO2 totaled 31.6 metric gigatons. Metric gigatons are a billion metric tons.
“Today’s climate challenges require new, scientifically supported solutions like storing the carbon dioxide created by use of fossil fuels, rather than releasing it into the atmosphere,” said Assistant Secretary for Water and Science Anne Castle. This new study provides the scientific underpinning needed to better manage options related to reducing emissions that contribute to climate change.”
Although the scope of sequestration included in this assessment is unprecedented, injecting CO2 into geologic formations is not a new process or technology. Carbon dioxide injection has been one method of enhanced oil recovery since the 1980s. The process works by flooding the oil reservoir with liquid CO2, which reduces the viscosity of the hydrocarbons and allows them to flow to the well more easily.
The USGS project results announced today represent an assessment of storage capacity on a regional and national basis, and results are not intended for use in the evaluation of specific sites for potential CO2 storage. Congress authorized the USGS to conduct the carbon sequestration assessment in the Energy Independence and Security Act of 2007.
In addition to geologic carbon sequestration, the USGS also studies biologic carbon sequestration— sequestration that happens naturally in trees, fields, and different types of ecosystems that store carbon. The USGS has already completed assessments for the Great Plains Region and the western U.S.; reports on the eastern U.S., Alaska and Hawaii will follow.