A guest blog by Bryan Hopkins
The words carbon capture pop up in our news these days with increasing frequency, particularly in this region as there are plans to install carbon capture technology in the biomass power station at Drax. But what exactly is ‘carbon capture’, and is it going to be worth waiting for?
Going back to nature, carbon capture is what plants do all through daylight hours: absorbing carbon dioxide from the air and sunlight to create plant materials by photosynthesis. Through the millions of years of the Earth’s existence these plants have slowly been converted into coal and oil, and as we burn them we release these millions of tonnes of carbon dioxide back into the atmosphere, which is why we have a rapidly developing climate crisis.
In recent times we have grown used to the idea that technology can solve all our problems, and this is no different with the climate crisis. Surely we can develop technologies that can suck all of the extra carbon dioxide out of the atmosphere and put it somewhere where it is not going to cause a problem? This is the reasoning behind the drive to develop Carbon Capture and Storage (CCS) technologies.
Looking first at how to remove carbon dioxide from the atmosphere, this is perhaps the most problematic part of the technology. Many ways to do this are being explored, but at this stage of technological development, all of them are very expensive and require large amounts of energy, which is, of course, somewhat self-defeating. The most effective way currently to remove carbon dioxide is at the point where it is being produced, in the process of burning a fossil fuel. This is why there is interest in installing CCS systems in power stations such as Drax. Unfortunately, the best systems at the moment can barely remove 50% of the carbon dioxide emissions — which of course means that over half of the gas continues to escape into the atmosphere.
Energy-efficient machines which can suck carbon dioxide out of the everyday atmosphere on a scale which can bring its levels back to what may be considered to be climatically safe levels are still science fiction.
The second stage of the problem is what to do with the carbon dioxide once it has been captured. Here, three main ideas are being explored. Perhaps the most likely is geological storage, pumping the gas into suitably secure holes in the Earth’s crust from where it will not escape. This idea is of particular interest to petrochemical companies and oil states because by pumping high-pressure gas into semi-depleted oil fields the remaining oil can be extracted (to be burnt and hence produce more carbon dioxide). Here we have a problem which has also bedevilled the nuclear power industry for decades: where can you safely store highly dangerous materials for the foreseeable and unforeseeable future? If we store millions of tonnes of carbon dioxide in an underground facility and geological activity cracks the facility open, the impact on life on Earth could be immediately catastrophic.
A second idea is to pump the gas into the deepest parts of the ocean, where it will dissolve in the water. However, this increases the acidity of the water and this could have unforeseen consequences for marine ecosystems which would eventually have major implications for terrestrial ecosystems. There is also no guarantee that ocean currents would not bring this acidic, carbon dioxide-which water back to the surface where it will escape once more.
The third idea for storage is to find ways to combine carbon dioxide with minerals so that a solid material is produced: for example, our White Peak limestone is a combination of calcium and carbon dioxide. If this could be done at a suitably large scale and at low cost this could be a very important technology, as the solid material would be easier to store and could have other uses. However, this technology is at an even less advanced stage of development.
Back in the 1960s when I was a small boy I looked forward to having my own flying car and going to the Moon for my holidays when I was 40 years old. These technological developments have not appeared, and I am glad that I did not depend on them happening. However, in these early years of the 21st century, we are in danger of continuing destructive economic systems based on a desperate hope that technologies such as CCS will save us. This brief review shows that we are at the very early stages of developing CCS technology and that there are absolutely no guarantees that the technologies can be made to work at a large enough scale or to be economically viable. It is notable that those most in favour of pushing forward on CCS technology are those energy companies and countries whose existence depends on the continued exploitation of fossil fuels.
It could be seen to be a form of insanity that we continue to burn fossil fuels, extract carbon dioxide and expect levels of the gas in the atmosphere to fall back to safer levels.
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