Hovering on the edge of consciousness, in a more immediate way than nuclear fusion, is the promise that carbon capture and storage (CCS) will solve that whole climate change, power generation thing.
Indeed only today the government's cost reduction taskforce for CCS reported back that the technology could be cost competative with other fossil fuels by the mid 2020's - assuming carbon prices pushed up the cost of those technologies and assuming the government put in place the policies - and funding - it needs to get there.
There are two powerful lobbies for carbon capture technology.
One can be labeled as ‘Industry’, the refineries and foundries that make all those useful material we use like steel, but necessarily emit carbon (standing here for all greenhouse emissions). Which is fair enough - there are few alternative suggestions out there, other than not having stuff.
The second group are businesses loosely termed the ‘fossil fuel industry’, they are hoping that they can avoid doing anything to limit fossil fuel use. One of the most attractive aspects of carbon capture technology, for a fossil fuel major, is that powering CCS then increases the amount of fuel you need to burn.
So, what are the issues with CCS?
1) Improbable Infrastructure?
Let’s start by seeing what would be required if CCS were to solve our emissions problem. Current world wide emissions are somewhat in excess of 35Gt of CO2 a year, or pushing up to 10Gt of carbon, and they keep growing every year. Once the CO2 is separated out and captured it has to be compressed for transport and storage, so highly compressed that it forms a supercritical liquid. It is, however, still an awful lot of liquid.
An estimate, given by the Qatar Carbonates and Carbon Storage Research Centre, was of 700 million barrels a day, or roughly 108 m3 (at 10 bars and 40 degrees this is 600-700 kg m-3). To be compared with total global oil production at around 85 million barrels a day.
In the book Sustainable Material - With Both Eyes Open they estimated that industrial and process emissions were responsible for 28Gt of CO2, or 8Gt of carbon. This is a volume of 16700 km3, compressed 370 times to form a supercritical liquid - this gives us 45 km3 of liquefied global emissions. To put this in perspective - they estimate this as 11 times the volume of current oil production.
Let me repeat, for CCS to take care of our emissions this means a volume of order 10 times the current volume of oil production. Put back into the ground. Safely, and securely. Every year. It took a long time to get the oil industry where it is today, building something bigger in a coule of decades is more than challenging.
But this is overly harsh. We don’t need to capture all our emissions immediately. Halving global emissions by 2050, in a strategy with CCS accounting for around 20% of the reduction is not such a big ask. That would be about 10% of global emissions, or roughly the same volume as oil production...
However, CCS is only appropriate for dealing with emissions from big, centralised sources, i.e.: power stations, not cars. Which are about 30-40% of our emissions. So it would still have to be fitted to the majority of the world's power stations - even if it only accounted for 20% of global emissions reductions.
2) Marginal Gain
Now, let us say that we did get a good chunk of CCS infrastructure up and running. How much can we store underground? And how long will it stay there?
There are several potential candidates for storing our bottled up emissions, fitting broadly into three groups. We can either pump it underground, into old gas and oil reservoirs, or coal seams say; we can dissolve it in the ocean or underground lakes; we can turn it into a solid by using mineral carbonisation, or by growing algae for bio-fuel.
Now all these options have different theoretical maximum and minimum storage capacities, necessarily lower practical ones, with storage integrities and environmental risks ranging from high to low. It is all very unknown, and more careful work is needed to find out the practicalities and consequences of each option.
However, it seems reasonable to say that the current realisable CCS capacity is good for 30-100 years of emissions. That is, we still need to get off carbon. It is not enough.
Yes saline aquifers (deep underground saltwater lakes) have a very large potential storage (2-3 hundred years of emissions), though at the moment we don’t know enough about them yet to say it will work.
Everybody’s favorite is storage in oil and gas reservoirs. For one, the integrity is probably high, as oil and gas had no problem staying underground for millennia. It could also be used to help push out extra oil and gas, which after all are useful substances. This gets over emphasised, as not may fields have the right conditions for enhanced recovery.
That said, the advantage is that some of the infrastructure is already in place. In gas fields where CO2 comes up with the natural gas being extracted they already have to separate out the CO2.
So, the marginal time gain is probably worth having. It could present a medium term solution, while we ultimately have to reduce carbon use to sustainable levels.
My hunch is if CCS gets going we will probably keep finding places to store it, so capacity won’t be a problem for decades we may be using it in.
3) Economics
So, CCS is starting not to look like a great option for dealing with all of our carbon emissions. What are the economic implications of pursuing CCS, at least for some things? What is the cost of retro-fitting our infrastructure?
Though the capital outlay of buying what-ever equipment is needed will be large, the biggest cost will end up being through loss of efficiency. The energy cost of capturing the emissions while you are making them comes across as a thermal efficiency hit of the order 10-13%. For an old coal plant this would reduce the thermal efficiency by a quarter, and mean needing to burn a third more coal to get the same amount of electricity out.
Compared to the cost of capture, the cost of transport, storage and monitoring is pretty small.
In terms of passing the cost onto the consumer, estimates vary. For example the modest 2-3 cents / kWh (or $40-100 per tonne of CO2 removed) is often reported - originating in a report by Shackley and Gough 2006 I believe. Some others give two or three times this. As subsidies go this is pretty reasonable.
What then is stopping it getting off the ground?
Partly there are objections because of the risk of cuckholding, that is of budget for low carbon investments being soaked up by CCS rather than addressing the underlying problem.
Another possible block is lack of ownership. As those involved in CCS projects tend to be consortiums of stakeholders, no-one owns the project or really takes responsibility for it.
Strange that something that is allegedly so reasonably priced is so sluggish...
4) Allocation
To me the killer issue is: who is going to get the underground space, given the time and capacity limits – that’s the same as saying, why is anyone interested in CCS?
Industry has to emit to produce steel, aluminum, paper, concrete and plastic, and EU regs could accidentally kill best practice without border controls.
For example, to promote best practice and ensure low carbon emission from Industry, it may be necessary to regulate about all steel used domestically, not just steel produced locally. Otherwise the local boys go out of business and we buy the cheap stuff from polluting foundries in India and China.
There is undoubtably cuckooing of industrial needs by power companies who don’t want to change their methods of electricity production and so join in with the lobbying. Given that we are likely to keep using fossil fuel in the coming decades, I would say we need any CCS capacity for the necessary emissions from useful stuff, like steel and concrete.
How about decarbonise the power sector now, promote improvements in efficiency, particularly material efficiency, then sort out the border protection for domestic production/consumption of material industries to promote best practice.
