Thanks for your detailed calculations on the quantities involved. Another critical factor not often mentioned is that if you have a power station far from suitable geology, you may need to pump pressurised or liquefied CO_2 a considerable distance. While venting CO_2 out of a smoke stack at high temperature doesn't present an immediate threat because turbulence mixes it into the atmosphere, a large-scale leak at ground level of cold gas could be catastrophic (see e.g. http://volcanoes.usgs.gov/hazards/gas/index.php#effects).

John, on your doubts about how a given concentration of CO_2 could affect the climate, have you worked the numbers (see e.g. http://chriscolose.wordpress.com/2008/03/09/physics-of-the-greenhouse-effect-pt-1/)?

There ia an unmentioned Problem. What problems there may be in a new technology are unknown because those problems do not exist untill the technology is introduced. When we invent technology we invent the associated problems. These are called side effects. The potential for unforseen side effects with this technology are enormous. We just do not know what we might be creating.

There are severe energy penalties even before the compression stage. The version which uses oxygen enriched air requires pressure swing absorption (PSA) via numerous banks of machines to achieve continuous high volumes. The post-combustion CO2 scrubbing process uses reversible chemical mixtures based on amines or ammonia. These processes need energy to refresh the spent chemical and to condense or make up evaporative losses.

Nonetheless I believe Rudd promised $500m or so for clean coal research in his useless watered down emissions trading scheme. That means he not only broke an election promise but he is away with the fairies on technology issues as well.

what an interesting and, i believe, authoritatative discussion by a relevantly qualified person of CCS. it's an article that should be compulsory reading for federal govt ministers enamoured of the CCS fantasy. i share [as a qualified civil engineer, for what it is worth] john harborne's scepticism that CCS is any kind of feasible large scale responsible solution to CO2 emissions from coalburning. anyone can put together a little 'experiment' to pump CO2 into the ground that 'works' - they'll pump a bit of CO2 into the rock under the Tuggerah Lakes power station, for example - there was a news item yesterday on this. But the issues of finding enough suitable accessible geological space, and risks of venting and pollution of groundwater, are the defining issues on any real scale.

disappointing twist in the tail, though - harborne, a metallurgist, turns out to be a sceptic about global warming induced by CO2, on what seem to be no more than vague a priori grounds, that john can't believe so little CO2 gas up there could make such a huge difference to the upper atmosphere's heat retention properties. but john is no more a climate scientist or upper atmosphere researcher than i am. i would prefer to trust the global scientific consensus reflected in four IPCC reports. there is heaps of good theory, and there is heaps of evidence of observed side effects in terms of arctic and greenland icemelt, atmospheric and ocean surface layer warming, changing weather patterns leading to inland temperate zone dessication, and increased cyclonic activity, etc etc.

what is it about climate change that makes otherwise sensible people -experts in their own fields - turn into denialists or sceptics, in the face of so much persuasive evidence? it is just that it is too scary for some people to accept that dangerous climate change is, almost certainly, happening?

I am rather amused by tonykevin 1's post. I probably know more about global warming theory (for that's just what it is … a theory) that the warmers are pushing, than I do about CCS. He has assumed that I am an expert in the CCS field and accepts my exposé without quibbling, but seems to think I know little about global warming.

Despite the four IPCC assessment reports, proof of CO2-driven global warming has never ever been produced by the so-called environmental scientists. Prof Tim Flannery is not a climatologist, nor is Al Gore, but the warmers take their every pronouncement as gospel. As far as persuasive evidence is concerned, Prof Michael Mann's hockey-stick graph, so loved by the warmers and initially by the IPCC, has been convincingly proven to be fraudulent.

The IPCC has based its projections for catastrophic climate change on the output from 23 computer models (GCMs), no two of which give the same answer. Talk about high-tech. crystal-ball gazing! Yet these same 23 models failed to foresee the downturn in global temperatures that have occurred over the past decade. Average global temperatures rose by only 0.7°C over the 20th century, but the average temperature has fallen by that same amount in the past two years.

Tonykevin 1, you talk of scientific consensus. Science does not operate by consensus, and that should be the first lesson you should learn.

John, a workmanlike job of demolishing CCS and much appreciated.
It is a pity that you turn out to be Climate Change Denier and that is the motive for the article. I believe it is quite pointless arguing with you people as you appear to be off in a little world (?cave)of your own.

We need to wave goodbye to the psychology of prior investment and make a determined start on building a sustainable Australia.The electricity generating industry is a very appropriate place to start.
Fortunately Australia has many sources of renewable energy - wind,solar thermal,tidal.Geothermal,while not strictly renewable,can provide large quantities of base load power for a very long time.
We also need to get started on a nuclear power scheme using advanced reactors powered by uranium or thorium.
Whatever you may think about the role of carbon dioxide in the atmosphere the plain fact is that burning coal is not a sustainable activity.Try applying the yardstick of sustainability to any of our current activities.If you are honest you may get quite a shock.