CO2 Legacy Issues

CO2 from point sources is often pumped underground (usually with the co-operation of the oil industry as the gas is used to force up more oil.) Our comment is that much work over many years during the cold war and later has established that the risks of pumping CO2 underground are far too high due to the fractured unstable nature of the crust. This risk often ignored and transferred to future generations. Carbon capture and burying it underground is only sensible if it is going to react with country rock to produce thermodynamically stable carbonate as supposedly is happening at the Orca plant near Reyjkavik in Iceland.[1 ] 

The Climate Action Network Australia (CANA) which is an alliance of environmental, public health, social justice and research organisations working together to fight Global Warming produced an interesting graph in a 2004 media briefing which supports our own modelling of geosequestration (downloadable under tools). The models vary depending on the emissions and response scenarios adopted but importantly they concurrently prove that with even with small amount of leakage which will be inevitable, that it is essential we adopt a permanent sequestration technology such as Gaia Engineering [2]. We hope to include some of our modelling in newsletter time permitting or the reader can use the tool provided to do their own.

The conclusions all depend on the leakage rate which of course can never be determined - the crust is instable in the long term and that is why we have the continents we do and so on. Researchers vary greatly in their assumptions and conclusions regarding a likely level of leakage. Whatever the scenario undeniably some leakage will occur because geological formations are not completely stable. They are for example disturbed by earthquakes caused by the movement of plates or upwelling of magmas. Another source of leakage could also be the instability of injection points over time [3].

Dooley and Wise[4], Hawkins[5], and Hepple and Benson[6] find that the annual leakage rate must be lower than 0.1% if geological storage is to be safe. The problem is that if the leakage rate is higher, targets for atmospheric greenhouse gas stabilization in the range of 450 to 550 ppmv become unattainable in the long term. Our own modelling in our new downloadable Gaia Engineering Process v Geosequestration Model under tools indicates that anything more than about .2% leakage which is quite possible would result in the problem getting worse after about 200 years and at best all geosequestration can do is buy us time.

The diagram below from CANA illustrates a scenario in which geosequestration is used as the exclusive greenhouse gas emission reducing tool for the next two hundred years and a leakage rate of 0.1% per annum is assumed. The graph shows that by the end of the 22nd century the entire ‘carbon budget’ of future generations would be consumed by leakage from past underground carbon dioxide storage. This would mean that future generations can not avoid dangerous climate change, even if they reduced their own greenhouse gas emissions to zero.

Fig. 9 - Impact of a 0.1% Leak Rate from the Underground Storage of Carbon[7]

In conclusion CANA said that "The assumption of exclusive reliance on storage may be an extreme one, however the example illustrates that emphasis on energy efficiency and increased reliance on renewable energy must be priority areas for greenhouse gas mitigation. The higher the expected leakage rate and the larger the uncertainty, the less attractive geosequestration is compared to other mitigation alternatives such as shifting to renewable energy sources, and improved efficiency in production and consumption of energy."

TecEco believe the graph demonstrates that a permanent form of sequestration is essential because of the leakage issue. Our view is that it will be too difficult given human nature for us to give up the remaining 7,000 gigatonnes of coal left on the planet as a source of energy and that the rate of conversion to non fossil sources of energy cannot possibly be quick enough. As Di Fazio has demonstrated - the correlation is just too strong [8] between world industrial product (WIP) and fossil fuel energy and thus emissions. At TecEco we think that reusing and recycling CO2 is the most promising form of sequestration yet devised.

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