The Carbon-Capture Carbonundrum?

Photo Credit: NASA

I posed this question in a posting way back in December 2007. It appears to remain largely unanswered (or possibly ignored?); but, in the light of the recent announcement by our government regarding proposals for a new generation of coal-fuelled power stations, I feel it could stand another airing. The unease I feel is this: quite apart from the whole raft of concerns raised by others in various places, there is the fact that for every 12 tonnes of carbon burned in fossil (or any other carboniferous ) fuel, approximately 32 tonnes of oxygen is extracted from the atmosphere. The scale of this "oxygen depletion" may, admittedly, be exaggerated somewhat because many fuels actually have a bound-in oxygen content to begin with, but still it is probably a good order-of-magnitude figure.

Now if the fuel is from a renewable source, then I suppose we can generally assume that the usual biological processes such as photosynthesis will eventually return the consumed oxygen to the atmosphere and, on balance, there is no adverse effect; if the fuel was from a fossil source, then although there will be an excess carbon dioxide input to the atmosphere, it is still conceivable that a proportion of it will also be "metabolised" by the ecosystem: for example, there may be accelerated/enhanced growth of vegetation, algae, etc in some land/sea areas, which could partially off-set it ...for a while.

Some of the excess carbon dioxide will surely not be recycled, though, and it is that fraction that we get concerned about with regard to global warming, of course. But as well as this hazard, there is the associated potential problem that a portion of the oxygen removed from the atmosphere by combustion is lost permanently. That would be bad enough in any case, but if all the carbon dioxide from a power-station were to be sequestered below ground then all of the oxygen consumed in its combustion process would go with it - for good; or at least for "... five thousand years at least ..." (which of course begs its own questions as regards the really long-term future of the planet).

So on this basis, it seems to me that what we should be aiming at, if anything, is true carbon-capture, and not capture of carbon dioxide. We should in other words be separating out the oxygen first and returning it to the environment.

And here we encounter a further little niggling problem: splitting carbon dioxide into its elemental components takes ... yes, you guessed it - energy! Logically (one assumes) this should not come from the burning of yet more coal, but maybe it could be provided by truly renewable sources such as wind, solar etc, or - if we really must - nuclear fuel.
So, why not just invest in them properly in the first place?

To be fair, there is now apparently an experimental plant in Germany that "cooks" sewage anaerobically to drive off the volatiles, which then become "new" fuel without comsuming oxygen. The only true waste is basically carbon black (charcoal) which actually has a commercial value in its own right, but does not present a global-warming risk. Of course, this approach is a rather different proposition from the coal-fired argument discussed above.

Now don't get me wrong - I am a firm believer that we face a lethal threat from human-generated global warming, and that all proposed solutions need to be examined properly and fairly. But that means identifying potential drawbacks too.

Perhaps I am being overly naive in my arguments relating to oxygen depletion, and maybe the effect will never be great enough to cause us concern. I just don't know. But I'd be really glad to hear other views. What do you think?

[Of course there are plenty of other arguments against this carbon-capture approach. For one thing, it doesn't avoid continued plundering of the earth's resources; and the supposed (by some) unsightliness of wind-turbines is surely as nought compared to the huge and visciously ugly scars left behind by open-cast mining operations? Then there is the matter of security of the energy supply. We would continue to be at the mercy of off-shore providers. Or am I very much mistaken?]

Mike

"M'aidez" call - already answered? A correction

One of Knutsford Royal Mayday's most respected and long-standing organisers has pointed out to me an inaccuracy in the following item I posted back in March 2008, and for which I must put the record straight ...

Knutsford "Royal" Mayday under threat? Whatever next?

In it, referring to letters appearing in the local newspaper around that time, I wrote this:

"But the event itself does not raise money for its own survival. On the other hand, it is very expensive to put on. Much of this cost goes into policing, especially owing to the fact that routes through the town have to be temporarily closed.

The thought of Knutsford without its Mayday is a bit like the thought of Cheshire without Jodrell Bank (don't forget to sign the petition, by the way).

I read a good suggestion today that those taking part could be asked to pay a small fee - say £2. This seems to me to be a reasonable and modest amount, yet it could really make a big difference. Actually, I think it should be made optional, and the amount left to people's discretion: if we value the tradition that much then we will be willing to pay for it. Knutsford is famous for being pretty well-heeled, after all. On the other hand (and perhaps not so well-recognised by the outside world) it is also home to many much less well-off families for whom it would be totally wrong to impose any financial hurdle to their participation.

Surely, those of us who can afford it would be prepared to dig into our pockets to save this gem of ours?"

I'm most grateful to my contact for letting me know that there is in fact a voluntary donation scheme for families taking part in the event: indeed it was devised by her, and already existed at the time I wrote the article. Moreover, she assures me that it has been very successful in raising additional funds each year. This is excellent news. In absolute terms I daresay it is still a drop in the ocean, and cannot hope by itself to guarantee the long-term future of the Mayday. But at the very least it does one exceedingly valuable thing: it demonstrates the considerable affection and high regard in which this unique festival is held by our townsfolk.

Long may it continue.

I do apologise for having got it wrong last March.

Mike

Happy Year of the Ox to All