Monday, 3 February 2014

Carbon Capture and Storage

During his lamentable time in charge of the Department of Environment and Climate Change, Ed Miliband brought in a rule stating that any new coal-fired power station should use carbon capture technology (CCS). This move was apparently a surprise to many in the department, and came after he was heckled by Pete Postlethwaite whilst at a film première in London.

The rule has been a disaster, and has essentially stopped any coal fired power stations from being built in the UK. Whilst this may be good for the environment, it should be noted that ten new coal-fired stations will start producing power in Germany over the next few years.

Coal power stations are cheap and brilliant at producing baseload power. The downside is that they are dirty and produce several greenhouse gasses, for instance CO2. CCS involves splitting carbon dioxide from gasses and placing it into a geological reservoir; this can be depleted gas or oil geological formations, or even the deep ocean. It has been used for many years in a couple of ways:
  1. In some gas fields, the carbon dioxide that is raised with the gas is stripped out and put back into the formation. 
  2. In some oil fields, CO2 is injected back into the reservoir to maintain pressure and keep the oil flowing. This is known as Enhanced Oil Recovery. 
This has led to the idea that CO2 can be stripped out of the flue gasses from coal power stations and then transported to a reservoir for storage, Here in the UK, the most obvious place are the gas and oil fields that have been depleted.

On the face of it, CCS seems like a brilliant idea: capture the atmospheric pollutant. So what are the problems?
  1. It has rarely been done on a large scale, with the reservoirs situated far away from the generators. When it is used, it is mostly used in gas or oil fields as mentioned above. 
  2. It dramatically reduces the efficiency of the power plants. Depending on the type of plant and the location of reservoir, the stripping and transport of the CO2 can take 15 to 45% of the power produced by the power station. 
  3. It is hideously expensive
  4. I have grave doubts about the capacity and security of the reservoirs. The reservoirs may have stored natural gas for millions of years, but that was before they were made into pincushions and emptied. And if CO2 does degas in a big way, it is much worse - and deadlier - than natural gas as it is slightly heavier than air. The Lake Nyos tragedy shows these dangers. 
  5. I think a little too much attention is being put on CO2 as an atmospheric pollutant, especially in comparison to other greenhouses gasses. Would we be spending the vast sums CCS would demand on the right target? 
I don't know what the answer is to green baseload energy, but I'm fairly sure that it's not large-scale CCS on power generators.

If we do go ahead with it, than there should be long-term and reliable checks on the integrity of any reservoirs, and monitoring for any leaks, along with warning systems to be used in the case of large-scale leaks.

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