Carbon storage

We all hear quite a lot about climate change especially this week as it’s climate week, but one thing I haven’t heard much about is carbon storage so on Thursday I took the chance to go to Professor Herbert Huppert’s Bakerian prize lecture Carbon storage: caught between a rock and climate change.

Don’t worry I’m not going to write a long extensive post on climate models, the data is too vast and besides it would be very long and you’d all stop reading before the end! That said, and before I go any further, all too often some parts of the media focus on short term trends in the data for dramatic effect to try and create uncertainty where there really isn’t any. The global long term trends clearly show that temperatures are already increasing and the polar ice caps are already melting.

Given that it is too late to completely avert changes to our climate, and our unwillingness to dramatically change the way we live, technological advances are now vital in our battle to survive. We need to find solutions that allow us to negate our future impact on the climate and solutions to the problems we will face as a result of the changes that have already begun.

The UK produces an average of 10 tonnes of CO2 per person per year, the USA and Australia 20 and China 5 (but this is steadily increasing). So what can we do with all this CO2 instead of releasing it into the atmosphere? This is a brief overview of Professor Hupperts opinion on some of the different carbon storage solutions.

Trees take up CO2, we could trap it in ecosystems. To trap the CO2 from all the UK power plants half the surface area of England would need to be covered in trees. This might sound attractive to some but especially given the predicted rise in sea level there simply won’t be enough land for the trees and all of the people.

We could store it at the bottom of the ocean. There are two major problems with this, firstly that would cause acidification of the oceans which would in time destroy the ocean ecosystems. In fact we’re already seeing some acidification and the resulting damage to coral from atmospheric CO2. Secondly, not all CO2 is produced near an ocean and transporting it long distances would be very expensive, we need local storage solutions.

Depleted oil reserves could have the CO2 pumped into them. This could be an option but as for the oceans one of the limitations is their location.

What about mineralization (the process that occurs when CO2 reacts with rocks to form carbonate)? This happens very slowly and so far the only way we know of to speed it up requires huge amounts of energy and would therefore be prohibitively expensive. Maybe if the technology improves this will become a more viable option.

Saline aquifers are plentiful and could potentially store a lot of CO2. If you pump CO2 down to below 800m it is compressed sufficiently to become a fluid and will take up a lot less space. This is already being done successfully at Sleipner in Norway where they are capturing the CO2 produced from processing natural gas. This is quite a simple idea, the aquifer is contained by rocks so once pumped into it the CO2 is physically trapped. Some of the CO2 will react with the salt water but this is a limited reaction and causes no particular concern, mineralization will also occur with the CO2 reacting with the rock. What is concerning is the prospect of a leak if there is a fracture which would over time lead to all of the CO2 be released again. One project in Australia has attempted to address this problem by using slopes so that if a leak occurs any CO2 that has already gone past the fracture will remain trapped.

In the USA saline aquifers have the potential to trap up to 3631 billion tonnes of CO2 which would be sufficient for around 500 years. If we are to make full this of this possibility it will require investment in the technology and the research to ensure we have a sufficient knowledge base to choose appropriate sites and fix any problems that occur.

Global temperature increases greater than 2°c are expected to cause widespread devastation, with increases of 4°C being catastrophic. Scientists have estimated that to limit the global temperature increase to 2°c the levels of green house gas emissions must peak before 2020 and fall 50% by 2050. As part of this global effort the UK needs to cut it’s emissions to 80% of the 1990 level by 2050. With science and innovation, as well as some sensible decisions, this can be achieved. Given the current economic climate it’s all too easy to cut investment in green technology and in revolutionizing our power industry but this would be a huge mistake.

If you don’t like the prospect of spending more on fuel, using nuclear power or investing in carbon storage then what action would you take to avert disaster?

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6 Responses to Carbon storage

  1. Di says:

    The Engineering perspective says:
    Hydrothermal energy is viable- naturally a slow process yes.
    Most effective is in areas where there are Geysers, hot underground springs (post volcanic activity hot spots) Iceland seems to be using geysers effectively however, to duplicate this method to extract CO2; pumping, rock fracturing and extracting are needed all of which use large plant and machinery to operate… How do we power/fuel these- currently large petrol or diesel machines and large plants powered by electricty or fossil fuels…
    Therefore the Carbon offset could be found to be marginal?

  2. Wow, that was very quick, I didn’t expect a comment already!

    Good point about hydrothermal energy, carbon capture is only a part of any solution. It would be better to obtain all our energy cleanly but as fossil fuel still makes up 85% of our power supply it will take some time to change 100% to alternatives. Carbon capture is something that can be done right now.

    No one thought to ask about the power supply to the capturing equipment that’s a really good question. I think it would still be worthwhile but it would be interesting to see the maths for that.

    • Di says:

      I read in the ATS (Australian Tunnel Society) Journal (one of my favs) that there has been project sucessfully completed in Bahrain.
      They have tunnelled (of course) “beneath the financial district to provide chilled water to Manama’s densely populated urban areas” with an aim to provide cheaper, most efficient and greener air conditioning to high density area where 70% of all the energy used there was for cooling buildings. It will be interesting to keep an eye on this topic to see if this helps reduce Bahrain’s carbon footprint????

  3. Interesting project, it will indeed be interesting to see how much difference it makes and if other cities notice how much money they could potentially save – depending on the cost of the tunnelling etc

    Do you think it would work in other cities with similar climates? Of course the use of precious fresh water also has to be considered carefully depending on the area, and in cooler less humid places building design can incorporate air flow to reduce or eliminate the need for air conditioning.

  4. liz Alsbury says:

    A very clear and concise description of the possibilities. Long live clear thinking.


    • Thanks,

      I tried to keep it to a sensible length so focussed just on the discussion of carbon sequestration. Trees, whilst we can’t grow enough of them, do capture carbon from the atmosphere which other methods don’t.

      I also didn’t mention the nuclear option as that’s a whole other debate, but I might write another post about that sometime.

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