Carbon capture and storage: Having your cake and burning it

Summary

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  • CCS is idea for sweeping carbon emissions under the rug
  • Driven by psychological need for an easy solutions
  • No evidence that it is actually practical
  • Would require massive and complex system
  • Combines multiple unproven processes
  • CO2 unlikely to stay underground for long enough
  • Could not stop global warming even if it worked
  • Number of pilot projects recently cancelled

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Carbon capture and storage (CCS) is an idea. The idea is very simple. The system we are all part of requires the burning of vast (and increasing) quantities of fossil fuels to provide the energy it needs. This is emitting equally vast (and increasing) amounts of carbon dioxide into the atmosphere which is destabilising the climate and threatening the survival of large sections of the biosphere, including ourselves. Since most people do not seem to be able to imagine any real alternative to the present system (a strange position to be in given how new and fast changing the latest incarnation of the system is) this presents something of a problem. What CCS does is alleviate this problem by imagining a world where the issue magically disappears. Fossil fuels can be burned without carbon dioxide being emitted into the atmosphere. The carbon dioxide is instead stored safely somewhere (usually underground). Suddenly there is no need to face any big questions about what we are doing and why. Everyone can go back to watching “reality TV” and stop worrying about that pesky climate crisis.

Unfortunately there is a small snag with this idea. Magic, or at least the sort of magic represented in Harry Potter films, doesn’t exist. If you really, really want something, it isn’t just a matter of finding the right magic words, or even right technological know how, in order to make it happen. Most things that human beings really think they want, they can’t have. This is because the physical world couldn’t care less about what we want. The hundreds of years of effort that alchemists put into searching for a way of transforming abundant metals into gold didn’t get them any nearer to their goal. The more recent attempts to build perpetual motion machines, in the face of the laws of thermodynamics, have not resulted in any greater success. While as Arthur C. Clarke said “any sufficiently advanced technology is indistinguishable from magic”, appearances can be deceiving. Just because technology looks a lot like magic if you don’t understand it, doesn’t mean it actually is magic. The idea of CCS is based on just such a fundamental misunderstanding of the nature of technology.

Just because people really want something to work doesn’t mean it necessarily will: transmutation of base metals into gold was never made to work despite many alchemists dedicating there lives to it

In reality the fundamental basis of technology isn’t knowledge (arcane or otherwise) but surplus energy. If a society like ours has large amounts of surplus energy (after meeting basic needs) then plenty of ideas will appear to make use of that energy. Most of those ideas will not be remotely practical and will never get beyond the ‘series of failed tests’ stage, but if there is the energy available then practical uses will be found for it. The problem is the selective memory of how this process plays out. Only the stories of the successful ideas are told. There are a hundred stories of an heroic inventor struggling in obscurity before making a break through that leads to a widely used technology but the stories of the vast numbers of ideas that failed to meet the practicality test are never told. For dramatic purposes the importance of that ‘eureka moment’ is often over played as well. Look at the genesis of most widespread technologies in more detail and you usually find multiple independent inventions over the period of a few years. This suggests a more situational explanation for technological development where technologies that are practical in any given era are likely to emerge to fill an available niche.

If this is so, the question becomes: Is CCS a practical solution whose time has now come or is it more like alchemy or perpetual motion machines, ideas for which there is a deep psychological need but no chance of a practical implementation? Given that the idea of CCS seems to have clearly emerged out of the need side of the equation, rather than starting as a practical process looking for a useful application, the odds are stacked against it being practical. One look at the various statistics for the fraction of patents that are ever commercially implemented shows that the vast majority of ideas never result in a practical technology. This should be unsurprising, as has already been stated, we are talking about technology not magic. Wishing for something to work will not make it happen. A very careful examination of the likelihood that CCS would ever become practical therefore seems prudent, before any decisions about the future are made based on it. Unfortunately prudence is in pretty short supply these days but that being the case it is all the more important that searching questions are asked about whether CCS is actually physically and economically practical.

So what conditions need to be met for the idea of CCS to be implemented. First, the separation and capture of the carbon dioxide needs to be practical and economic. Ditto for the transportation of the captured gas to where it will be stored. There must also be enough space available to practically store the captured gas. Injection of the gas into the storage locations must be similarly practical and economic and finally the gas must actually stay in the location it is placed in and not leak back into the atmosphere. All these processes must also consume only a fraction of the energy produced by burning the fossil fuels in order for it to remain a useful energy source. CCS is therefore not really a single technology but a whole series of technologies which will need to be employed in concert over wide geographical areas (from where the fossil fuels are burned to where the carbon dioxide is stored) in order to make it a reality. None of these separate stages have been demonstrated on a large scale let alone integrated into working system. The need to build a whole new complex system, on a par with the whole electricity production and distribution system, out of a set of technologies that have yet been shown to work, does not inspire a great deal of confidence in the proposition of CCS.

Global carbon dioxide emissions exceed 30 billion tons per year: a massive problem which is very difficult to sweep under a rug

Separation and capture of the carbon dioxide is the first major issue and presents a number of challenges. Separation can potentially occur before or after combustion. Post combustion has the advantage that it could be retrofitted to existing power stations etc. Tacking this extra process onto existing installations will always increase costs and reduce the efficiency of the process however. Actual ideas for how this might work are numerous but largely untried. Amine based solvents have been widely used on smaller scales but are expensive and may have severe associated health issues. There are various other ideas but they are even more speculative and untested. Alternatively the separation could potentially be implemented before combustion. While it is much harder to tack onto existing infrastructure it might result in a more efficient process. This usually involves converting the fuel into hydrogen to burn and carbon dioxide to store before combustion, using an integrated gasification combined cycle (IGCC) process. This might potentially be more efficient than post-combustion but would mostly require building new power stations etc. As with post-combustion it is still very experimental. Alternatively an oxyfuel (pure oxygen) combustion process can be used. This puts the main effort into separating the oxygen from the air and burning the fuel with pure oxygen so the main products are water and carbon dioxide, which can easily be separated. In any case capture of more than 90 percent of carbon dioxide produced seems unlikely to be practical and it will always come with significant costs.

Transportation is also a significant problem for CCS. While power generation and industrial uses of fossil fuels tend to be highly centralised, other sectors like transportation and residential users are widely distributed. Collecting carbon dioxide from these sources and bringing it together for storage seem likely to be insurmountable problems. A massive increase in electrification (electric cars and home heating) might be used to try to get around this problem, but only at the expense of massive capital and efficiency costs. More generally the locations where the carbon dioxide is produced will not in general coincide with the places where it might be possible to store it. In most cases it will be necessary to compress the carbon dioxide and pump it through pipelines over considerable distances to the location where it is to be stored. This will also require large infrastructure costs and lower the efficiency of the process. There are also significant safety issues involved since pipelines can leak or be broken and while carbon dioxide does not explode it can suffocate people in an extremely insidious way. Finally, in the real world, over 5 percent of natural gas leaks between the well-head and the end user and it seems unreasonable to expect any greater level of reliability from a similar system taking a gas in the opposite direction.

Carbon capture and storage: a complex system involving capture, transport and storage of carbon dioxide

This raises an even more important question. Is it possible to contain the carbon dioxide that is stored, for a long enough time-scale to avert catastrophic climate change? Studies of the effects of different leakage rates suggest that a rate of 1 percent per decade would not do much more than temporarily delay the effects of catastrophic climate change while a rate of 1 percent per century would still eventually result in potentially dangerous warming. A rate of 1 percent per thousand years would be needed to ensure any reasonable level of long term safety. This constraint definitely rules out one suggested option of unconstrained disposal in the deep ocean (other issues include increase ocean acidification, potential conversion to methane by bacteria and benthic life forms). It is unclear if underground storage could achieve the necessary leakage rates. Re-injecting carbon dioxide in the place of extracted fossil fuels is not feasible since the carbon dioxide that results from burning the fossil fuel takes up between 110 and 500 percent of the volume when pressurised, depending on whether it is gas, oil or coal. Injection into saline aquifers would provide significantly larger volumes but would still be unlikely to be particularly feasible. This would also likely encounter all the water and earthquake issues associated with fracking. In particular the subsurface damage caused by earthquakes induced by the injection might well increase the leakage rate. Also the proliferation of shale gas extraction will result in drilling vast numbers of wells across large areas which is likely to further compromise the integrity of saline aquifers.

Disposal of carbon dioxide in the oceans: Plenty of space but unlikely to stay down there for too long

Even if CCS did work as advertised it wouldn’t really change much. Fossil fuels are running out fast and a transition away from them must happen soon in any case. More importantly it isn’t possible for CCS to have the necessary effect on emissions to avert catastrophic climate change. In an incredibly optimistic scenario where 90 percent of carbon dioxide is captured for half of all emissions (power and industrial users) with a 25 percent loss in efficiency for those processes, the resulting cut in total yearly emissions would be approximately 40 percent. However since the whole rational for CCS is the avoiding of more drastic changes to the system this would only be at all likely within an otherwise ‘business as usual’ scenario. It would therefore be accompanied by an overall growth in emissions from continued pressure for economic growth and a growing carbon intensity of energy systems as more extreme energy methods are brought into play. This would likely offset a large portion of the emissions cuts due to CCS. Cuts of 6 percent a year in emissions are needed to have a chance of not destabilising the climate, starting now and resulting in over a 90 percent cut over the next few decades. Even if an eventual 40 percent cut due to CCS was possible it would take a decade or more to even begin. Cumulative emissions over the next few decades, which are what really matters, would therefore not see much of a decline with CCS.

Fundamentally the major issue with CCS is that nature has already captured and stored the carbon in fossil fuels over a period of many millions of years, using vast amounts of energy from the sun to do so. The idea that the genie can be squeezed back into the bottle after it has been released is delusional to say the least. The energy and cost of safely re-concentrating the carbon and returning it to the ground would far exceed the utility of burning the fuel in the first place. Since if that were the case fossil fuels would no longer be an energy source it is clearly not going to happen and therefore CCS is always going to be a token gesture. At its core the main utility of CCS is as an enabler of continued emissions. By promising that this new power station will be built CCS ready (which basically just means there is some land available next to it to tack on a CCS plant if it ever became feasible) or that existing emitters could be retrofitted at some point precluding the need to shut them down, the idea of CCS provides the justification needed to carry on burning fossil fuels without restraint. In the end CCS is an idea and that is what matters, the idea not the reality. What that idea could do is block any real response to the predicament we find ourselves in.

Despite this there is a massive push to make CCS the alternative to having to worry about actual cutting of emissions. At both the EU and UK government levels, CCS trials are being encouraged with the offer of large grants to energy companies. A government funding competition initiated four years ago to fund a large scale trial of CCS ended in a shambles in October after a consortium led by ScottishPower pulled out of plans to build facilities to capture a sixth of the carbon dioxide emitted by Longannet, the UK’s second-largest coal power station. The reason given was that the £1 billion grant on offer was insufficient to ensure that the project would be economically viable. This has added to a string of recent cancellations of CCS projects worldwide, including the recent cancellation of a $1.4 billion pilot project in Canada because it was not economically viable. In the UK the government’s response has been to announce a new competition to try to resurrect CCS trials. Whether this one will have any more success than the last remains to be seen. However to see CCS in these terms is to miss the whole point. Whether it ever gets off the ground or not is irrelevant. CCS is about psychology not engineering. As long as there is the promise of CCS dangled before them it will allow those people who cannot face abandoning the current system an excuse for not facing up to the change that needs to happen. CCS could be considered as part of a category of “Extreme Greenwash” along with similar ideas like geoengineering.

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