Storing Carbon Dioxide Underground - Is Carbon Capture A Good Idea?

Carbon Capture and Storage (CCS) is still being developed and isn't in operation in any large scale power plants at the moment. The New South Wales government plan to have CCS working in a full scale power station by 2013. The problem is, there are additional energy needed to separate the carbon dioxide from other waste gases. There is also the cost of fitting equipment to do this, and transportation and storage costs.

Capturing CO₂ 

There are a couple of proposals for carbon capture technologies. 'Pre-combustion carbon capture' separates the fossil fuel into CO₂ and H₂ before burning. This method could only used in new power plants, as it requires close integration with the combustion process.

'Post-combustion carbon capture' uses the flu gas, and extracts the CO₂ from the other gases (mainly nitrogen and water vapour). This technique could be retrofitted to existing power plants that use fossil fuels.

Storing CO₂ 

Once the carbon has been captured, it could be piped to undersea lakes, or into rocks deep below ground. It is suggested it would return to a mineral form which could not re-enter the atmosphere. As the density of CO₂ increases the lower underground it is pumped, large amounts could be stored in comparably small spaces. The storage process is not fully proven though, leakage could be a big health problem. The leakage from natural CO₂ sources has been known to cause a number of deaths. Although CO₂ itself is not poisonous, when it displaces large amount of air, the lack of oxygen can suffocate.

There is also the question of how much worldwide capacity there is in saline aquifers, and other places where they plan to store the gas. There have been estimates, but it's critical the storage solution does not leak into ground water, or the air above. Graham Thompson provides a much more in depth look into the possible pitfalls of carbon capture.

Many people think carbon capture is diverting research from other technologies that could reduce the production of carbon dioxide altogether. It does seem a bit strange to be pumping a load of potentially dangerous gases into the ground beneath our feet. It is a useful political tool to show willing for preventing climate change, without closing down all fossil fuelled power stations. Perhaps using CO₂ to grow algae for biofuels could be a better option than simply putting it in a hole.

Ed Milliband certainly thinks it's a good idea though. UK coal fired power stations may all need to be fitted with CCS in the future.

Published - Tue 27th Oct 2009 15:35:28