Re: Clean Coal Power - An Illusion?

Bolaleman wrote:
Here I come back to the
question I asked at the beginning: how safe and
permanent is a geologic storage of the CO2 as applied in modern CO2
coal power plants (i.e. bottling and pumping it underground)? Can this
be a solution? We need to consider this option at least as an interim
option until we changed our energy supply resources.


I'm all for taking off CO2 at the stack, and reusing it for other industrial purposes. In most cases, this doesn't sequester anything, but may prevent other CO2 generation where CO2 is the desired product.

The answer to the question is where, and what geology, hydrology and depth the CO2 would be stored, as what value, if any, you put on subterranean ecosystems, as well as how much energy (and CO2) it would take to transport the CO2 to a suitable site.

Geology: one city in Missouri has a pilot project to pump gaseous CO2 beneath 1800 feet of carbonates, containing two aquifers, the upper one from which they get their drinking water. Stupid idea.

Hydrology: Although CO2 is heavier than air, and tends to pool underground, it would also travel downgradient if the host rock is tilted, or it gets admixed with water. CO2 + water is corrosive to carbonates (that's how caves are formed by natural levels. Industrial levels of acidity would increase the corrosion. How this would impact surface water would strictly be a matter of local topography, 'tightness' of the storage rock, etc.

I know CO2 injections are used to force oil out of oilfields, at depths over 10,000 feet. Perhaps this environment could be feasible, however, most coal fields are in sedimentary rock, and that often means sandstones, shales and limestones in thinly bedded cyclothems. This would mean off-site disposal, involving transport (energy use.)

Intense subsurface mapping would have to be done in order for underground storage to be a viable option. Is this feasible?

Ecosystems: We're not just talking microbes, here. There are fish and salamanders in aquifers up to 5000 feet under Texas. These are oxygen breathing creatures just like us. Subsurface biology, (called phreatobites) are very little understood except where we can see it in caves. Do we kill it off without knowing and say, "Too bad" ?

I'd think there would be some places where underground CO2 sequestrations is OK (just like there are places where it is OK to site a landfill) but just pumping underground willy-nilly (which likely would happen -- sort of like everyone using sinkholes for trashdumps in rural America, never knowing they were drinking their own dead cows) probably wouldn't be good in the long run.



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