Bizarre Results of Carbon Dioxide Capture and Storage

 

 CCS (originally called carbon capture and sequestration) is a neglected method of limiting green house gas accumulation in our atmosphere from large electric power plants.  Because of costs and lack of commitment by government and industry, no full sized pilot plant has been built or retrofitted to demonstrate the feasibility of CCS even though the technology is well worked out.  Perhaps the greatest usefulness of CCS will be temporary continued use of old power plants in their declining years.   

 

Any discussion of climate change needs to emphasize that many methods of mitigation of greenhouse gas accumulation need to be used together to have a large and prompt effect, and CCS will be slow in coming because of no money for constructing a demonstration project. 

 

The most obvious technical question about CCS is will the carbon dioxide (CO2) be reliably retained underground?  We cannot be reassured until after centuries of monitoring for leaks.  Questions will still remain.  For example, Archer, Daniels, Midland Corporation is “donating” carbon dioxide to be buried from a corn processing plant near Decatur, Illinois.  Within a decade a million tons of CO2 will annually be injected deep in the earth below impervious shale strata.  Even total success of this test site will not be totally reassuring without recurrence of a nearby earthquake as large as the unexpected one at New Madrid, Missouri, in 1811. 

 

If we accept the possibility of unlikely leaks from such causes, this could be justified by the fact that we had bought a century or so of time to get more permanent control of CO2 production under way and that a slow leak would not be locally toxic. A fast leak could be disastrous, illustrated by volcanic Lake Nyos in West Cameroon (1986) that released a large amount of CO2 that had gradually accumulated in the deep water from volcanic hot springs.  Temperature changes resulted in the water of the lakes turning over.   Surface fresh water had prevented release of CO2 until some deeper water was suddenly exposed to the air at the surface causing so many bubbles that all the deep water was promptly brought to the surface.  The CO2, which is heavier than air, replaced the surface air down the valley and suffocated 1800 people in villages as far as 17 miles from the lake.

 

All of the above is well known by experts and has been taken into account in planning initial pilot projects like the one in Decatur.  Something that I have not seen in the scientific literature or heard at scientific meetings is that CCS stores all of the oxygen with the CO2 that it sequesters---oxygen that didn’t exist in the atmosphere until photosynthesis began about two billion years ago.  Fossil fuel is the result of storage underground of almost all the carbon from the CO2 of  earth’s primordial atmosphere as photosynthesis released the oxygen.

 

The following probably depends on the reasonable assumption that, on geological time scales, volcanic emissions of CO2 approximate the carbon content of carbonate rocks deeply buried by tectonic subduction.  All of this means that if we burn much, let’s say half, of all the remaining fossil fuel and permanently sequester the CO2 underground, our atmospheric oxygen content would drop from about 20% to about 10%---obviously this would take millions of years.   So in principle this argument demonstrates that carbon capture and storage cannot be a permanent solution to our present dilemma, because any appreciable reduction in atmospheric oxygen would reduce the area of habitable land by causing more altitude sickness at lower elevations---more evidence for declaring CCS appropriate only for prompt control of greenhouse gases during the next century or so.

 

John A. Frantz, MD

March 2, 2010                            

 

Preach the Gospel at all times.  If necessary, use words. - attributed to St. Francis of Assisi