Carbon dioxide storage in the Tucson Basin

One way to deal with carbon dioxide emissions from fossil-fuel-burning power plants is to bury the carbon dioxide underground. Deep sedimentary basins such as the Tucson Basin have been proposed as possible depositories.

Tucson-basin

The Arizona Geological Survey has a new report “Geologic Evaluation of the Tucson Basin for Carbon Dioxide Sequestration Potential.” The citation for the report is:

Gootee, B.F., 2012, Geologic Evaluation of the Tucson Basin for Carbon Dioxide Sequestration Potential. Arizona Geological Survey Open File Report, OFR-12-40, v 1.0, 11 p., 3 plates

Besides the text, the report includes a geologic map and cross-sections, all freely downloadable.

The press release from AZGS says in part:

“A viable geologic repository for sequestering carbon dioxide must meet three conditions. First, it must host a substantial volume of porous and permeable rock or sediment at a depth of more than 800 meters (2,625 feet); a depth sufficient to maintain carbon dioxide in a supercritical state where it behaves more like a liquid than a gas. Second, the repository must host saline groundwater – to prevent contamination of fresh water aquifers. Third, it must be capped by a continuous impermeable layer of clay, salt or some other coherent and impermeable material, to prevent carbon dioxide from migrating surface-ward.”

The report itself concludes:

“A preliminary evaluation of the storage potential for CO2 in saline-permeable strata below an impermeable caprock in the Tucson basin is inconclusive. This is primarily due to the dearth of deep well data in the basin. Permeable strata below 800 m (2,625 ft) depth is sufficiently thick and potentially favorable for CO2 sequestration; however, the lack of salinity data for deep aquifers precludes an adequate assessment of storage volumes in saline formations below 800 m. Based on available data, the presence of an extensive seal or capping unit near or below 800 m (2,625 ft) depth could not be identified.”

Funding for the investigation is supported by the Department of Energy and by WESTCARB, a consortium of seven western U.S. States (including Arizona) and one Canadian Province.

Comment:

As I have written in a previous post: Clean Coal: Boon or Boondoggle?, “While carbon capture and storage (CCS) may be technologically possible, it makes no sense either economically or scientifically. It is a solution seeking a problem; it is utter wastefulness.” The whole idea results from the still unproven contention that carbon dioxide makes a major contribution to global warming. CCS schemes also provide no proof that they would make a measurable difference. Furthermore, carbon dioxide is a salable commodity; it is used by the oil industry to flush oil out of the rocks. Why bury it first?

Having voiced my opinion on the folly of CCS, please note that the Arizona Geological Survey does not judge the merit of the program, they only assess the geologic capacity of certain basins to provide the proper geologic conditions to make it work.

For more information on the Tucson Basin see: What Lies Beneath the Tucson Valley.

The Arizona Geological Survey has also been involved in assessing the geothermal potential of the region, see: New Source of Geothermal Energy in Western US and Arizona Geological Survey Leads Geothermal Energy Study.

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