USGS REPORT SAYS U.S. HAS 3,000 GT OF CO2 STORAGE CAPACITY

Tamar Hallerman
GHG Monitor
6/28/13

The United States has the potential to store between 2,400 and 3,700 gigatons of CO2 in technically accessible sedimentary basins nationwide, the equivalent of more than 500 times the country’s annual energy-related CO2 emissions, according to a new report released by the U.S. Geological Survey this week. Billed by the Department of Interior as the first-ever comprehensive assessment of the county’s CO2 storage potential, the Congressionally-commissioned U.S. Geologic Carbon Sequestration Assessment lists the Gulf Coast as the region of the country with “by far” the most potential for the geological sequestration of CO2. The assessment shows “that the United States has the potential to store an enormous amount of carbon dioxide,” Interior Secretary Sally Jewell told reporters June 26. “If enough of that storage capacity is technically-accessible and proves to be environmentally and economically viable—and those questions have not yet been answered in this study—geologic carbon sequestration could help us substantially reduce the man-made carbon dioxide emissions that contribute to climate change.”

Project Chief Peter Warwick said USGS did not assess the storage potential of wells undergoing enhanced oil recovery in the report since it will be the focus of a follow-up study in the coming years. DOI did consider all of the country’s deep saline formations and oil and gas reservoirs without the potential for tertiary recovery onshore and in state waters, but only further examined sedimentary basins with sufficient depth—between 3,000 and 13,000 feet below the surface, considered the ideal depth for maintaining the temperature and pressure needed to keep CO2 in a liquid state to prevent escape. The assessment also eliminated from consideration all areas with groundwater sources that are considered freshwater under Environmental Protection Agency standards and all reservoirs that could not be accessed using today’s technology for pressurization and injection. USGS said it also excluded the storage potential for the country’s unmineable coal seams, unconventional resources like shale, “tight” sandstone and basaltic rocks, since “little is know about the large-scale CO2 storage potential” in those formations. “USGS assessment methodologies still need to be developed to address these types of resources,” according to the assessment. Once that criteria was considered, USGS said it evaluated a total of 36 sedimentary basins for their CO2 storage potential, but did not take into consideration factors like economic viability or accessibility due to land management or regulatory restrictions.

The assessment found that those 36 basins cumulatively had a mean CO2 sequestration potential of 3,000 Gt. “For comparison, the U.S. Energy Information Administration estimates that in 2011, the United States emitted 5.5 metric Gt of energy-related CO2, while the global emissions of energy-related CO2 totaled 31.6 metric Gt,” USGS noted in the assessment. Of that 3,000 Gt, two-thirds, or 2,000 Gt, is found in what USGS called the coastal plains region, which encompasses the Texas coast, Louisiana, Mississippi, Alabama and the Florida panhandle. DOI’s research arm said it also found significant capacity in Alaska’s North Slope, with a mean storage capacity estimate of 270 Gt, as well as smaller areas of potential in the Midwest like the Illinois and Michigan Basins, as well as the Williston Basin of North Dakota and eastern Montana. The report said there is also storage potential in the Appalachian basin in West Virginia, Pennsylvania and eastern Ohio, as well as in the Rocky Mountains and Texas’ Permian Basin.

Results ‘Comparable’ to Other Fed Estimates

DOI officials touted the assessment during a conference call with reporters this week. “This assessment is, frankly, nothing short of groundbreaking,” Jewell said. She added that the assessment was the first “realistic view” of technically accessible carbon storage capacity in the U.S. USGS said the report “goes further than all previous assessments in considering the viability of sequestration” in a supplementary fact sheet.

However, the USGS assessment is far from the only U.S. government report gauging the country’s storage capacity. The Department of Energy has released several storage analyses, most recently an “atlas” of storage potential in the U.S., Canada and Mexico. Released last year, that report maps the country’s storage capacity against the locations of the continent’s 2,250 largest point sources. It estimated that North America’s sedimentary basins have the potential to sequester emissions for at least 500 years, the equivalent of at least 2,400 billion metric tons of Co2. USGS said its results are “comparable” with DOE’s assessments but that there are a few differences. “The USGS assessment methodology and assessment results are unique among the various assessments mentioned above, because the USGS methodology is fully probabilistic and better accounts for the range of uncertainties found in geologic settings,” the report stated.