Potential Impacts of Leakage from Deep CO₂ Geosequestration on Overlying Freshwater Aquifers

Mark G. Little[1] *[2] ^† and Robert B. Jackson[2] ^†[4] ^‡

Center on Global Change, Duke University, Durham, North Carolina 27708, United States, and Nicholas School of the Environment and Biology Department, Duke University, Durham, North Carolina 27708-0338, United States

Environ. Sci. Technol., Article ASAP

DOI: 10.1021/es102235w
Publication Date (Web): October 26, 2010

Copyright © 2010 American Chemical Society

* Corresponding author phone: (919)681-7180; fax: (919)660-7425; e-mail: [5] 6r4h@post.harvard.edu., † Center on Global Change., ‡ Nicholas School of the Environment and Biology Department.

Quoted from the abstract:

Carbon Capture and Storage may use deep saline aquifers for CO₂ sequestration, but small CO₂ leakage could pose a risk to overlying fresh groundwater….([6] Full Story and links to study report and supporting information)

(Thanks to Anthony Watts at [7] wattsupwiththat.com)

The study report is behind a pay wall.  The cost of accessing the report is $30 for 48 hours — more than I can afford to pay.

The [8] Shell CCS Project (CCS meaning Carbon Capture and Storage or, correctly, CO2 Capture and Storage or Sequestration) in the area NE from Fort Saskatchewan, with a CO2 pipeline proposed to run north of Bruderheim, crossing the North Saskatchewan River and then running to the vicinity of Thorhild, where the CO2 is to be injected at a depth of about 2,400 m underground, will inject the CO2 into deep layers of porous rock that may border on saline aquifers into which the injected CO2 may and quite possibly will expand.

The study by Mark G. Little and Robert B. Jackson from Duke University identified that when CO2 was bubbled for more than 300 days through core samples from injection sites, “CO₂ caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude.”  That means  increases in concentrations a hundred-fold and more.

The study furthermore showed, “Potentially dangerous uranium and barium increased throughout the entire experiment in some samples.”

However, although some of that is bad news, the study also identified that “Manganese, iron, calcium, and pH could be used as geochemical markers of a CO₂ leak, as their concentrations increase within 2 weeks of exposure to CO₂.”

From reading Shell’s information that has been provided to me as of now, I neither recall that [9] Shell’s CCS Project (also known by the creative name “Quest”) will employ such markers nor what action will be taken by Shell if a CO2 leak occurs underground at their CO2 injection sites.  That does not mean that Shell does not have contingency plans for possible CO2 leaks into overlying fresh groundwater.

Shell could well have contingency plans for possible underground CO2 leaks, but from the information provided at their Bruderheim open house (Nov. 3, 2010) it appears that Shell relies on the assumption that the CO2 they propose to inject will not move to the surface for at least a thousand years.

It is comforting to know that if nothing goes wrong with the premises of Shell’s CCS Project,  the residents who draw their drinking water out of the wells in the large area into which the injected CO2 will expand will be safe for at least for an estimated 1000 years.

Mind you, if something does go wrong, then all bets are off, and there is no telling as to what steps may  need to be taken to alleviate the impact of increases of mineral and metal concentrations in drinking water to objectionable and dangerous levels.

Have a look at [10] what a CO2-driven water geyser looks like.  Here is [11] more information on how the Chaffin Ranch Geyser came to be.