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expert reaction to study looking at carbon capture and storage and climate targets

A study, published in Energy & Environment Science, has investigated whether potential carbon capture and storage (CCS) capacity will be sufficient to produce a carbon sink large enough to meet Intergovernmental Panel on Climate Change (IPCC) targets.


Prof Stuart Haszeldine, Professor of Carbon Capture and Storage, School of GeoSciences University of Edinburgh, said:

“It is well understood that there are immense potential resources of CO2 storage around the world.  So carbon capture and storage is an essential component of future actions for climate defence.  But the rates of development in this article remain extremely optimistic for two reasons.

“First the economic driver used to project CO2 storage in this model is the USA method enhanced oil recovery.  However that profitable activity currently produces as much additional carbon as it stores, although that could be configured to store carbon with different economic incentives.

“Second the quantity of storage assessed worldwide to commercially investable standards is tiny.  Experience shows that regulations and infrastructure practicalities produce 5 to 10 year delays and slow the pace of construction.  Building an infrastructure equivalent to the global oil industry in less than 30 years is unlikely.

“This study is welcome because it confirms again that an immense storage resource is frequently being ignored by environmental and political policy.  To achieve the essential storage modelled theoretically will need fundamental shifts by individual countries to mandate CO2 storage with a Carbon Takeback Obligation, combined with a rapid systemic reduction in extraction of fossil carbon.”


Dr Greg Mutch, Newcastle University Academic Track (NUAcT) Fellow, Materials, Concepts & Reaction Engineering (MatCoRE) Group, School of Engineering, Newcastle University, said:

“We must capture carbon dioxide to stay below 2 °C.  Once we do, we can either use it or store it.  Using it is unlikely to help significantly (< 1% of net global carbon dioxide reduction)1.  Storage on the other hand will help significantly, as we likely have the capacity to securely lock away carbon dioxide emissions for very many years to come.

“However, this study correctly highlights that storage estimates often come with very large uncertainty (orders of magnitude) and therefore an approach that aims to understand what we will *need*, not an estimate of we will likely *have* available (with large uncertainty) is very useful.  This work finds that we will likely *need* ~103 Gt storage capacity, compared to the central estimates of ~104 Gt capacity that we *have*.  However, it is very important to note that we are currently injecting carbon dioxide into <101 Gt storage capacity, with ~102 Gt of capacity discovered and outlined as having commercial potential2.  Taken together with the modelling in the paper, this implies that the exponential growth rate in storage capacity will have to be maintained for a long time, at “the upper limit of historical exponential growth duration for energy technologies”.  Also, it is important to note that if the storage growth rate is faster earlier, we ultimately will require less storage capacity (and will have lower associated cost).

“This work correctly highlights that to achieve the sustained growth required, we will most likely need “additional policies and financial mechanisms to incentivize the capture and storage of CO2”.  It is also important to understand that storage capacity is not distributed evenly across the globe – if we take Europe as an example, the UK has one of the largest storage potentials, implying that this is a unique strength for the UK and that it could be used to create new markets and jobs in the UK.  The UK government itself identifies clean growth as “one of the greatest industrial opportunities of our time”3, and carbon dioxide capture and storage should play a central role for clean growth in the UK.”

1. Mac Dowell N et al. 2017 The role of CO2 capture and utilization in mitigating climate change. Nat. Clim. Change. 7, 243-249. (doi:10.1038/nclimate3231)




Miles Seaman CEng, CEnv member of Institution of Chemical engineers, said:

“The emphasis of this view is on the available capacity to store CO2 (presumably in spent oil and gas reservoirs).  The problem is that given the fact that the capture ’technology’ has been on the cards for many years, no really large emitter (i.e. say a 1GW fossil power station) has installed and operated a plant to achieve such capture at this “commercial” scale so neither the technology nor the capacity to implement is to be found anywhere.  Hence the question of whether this pipe dream will be realised is in question.”


Prof Eric Mackay, Foundation CMG Chair in Reactive Flow Simulation, the Institute of Petroleum Engineering, Heriot-Watt University, said:

Does the press release accurately reflect the science?

“The press release does reflect the content of the paper.

Is this good quality research?  Are the conclusions backed up by solid data?

“In the sentence “It also found that that the current rate of growth in the installed capacity of CCS is on track to meet some of the targets identified in IPCC reports, but that research and commercial efforts should focus on maintaining this growth while identifying enough underground space to store this much CO2” the first part of the statement appears well founded.  However, one has to bear in mind that we are currently at the very early stage of development of CCS capacity, that what development there has been to date has been largely influenced by government directives and government support, and that the rate of growth that needs to be maintained is not linear, but exponential.  Thus the second part of the statement is the more significant in the long term.  Getting the very early stages of an exponential growth curve correct helps demonstrate the modelling assumptions fit the observed data thus far.  The real challenge is growing the capacity exponentially, particularly in a world now facing a very uncertain economic future.

How does this work fit with the existing evidence?

“There is a good match to the historical data, and it seems appropriate to consider the impact of various demand scenarios on supply.

Have the authors accounted for confounders?  Are there important limitations to be aware of?

“The major limitation is that readers of this article should not take an attitude of “that’s OK then – we’re just doing fine”.  I would be confident the authors would not wish that impression to be conveyed.

What are the implications in the real world?  Is there any overspeculation?

“The value is that the model gives us a target to measure actual growth against to indicate whether the world is developing the CCS capacity at the rate needed.  The point is that growth rate is exponenetial, but the model allows us to predict what it should be under various demand scenarios, and thus we can measure success or failure much more responsively.

Is this good news?  Are we in a better position than we thought?

“We have a better ability to predict where we should be at each step of the journey, and therefore better ability to identify what our true position is.  However, we are currently at the very early stages of what needs to be exponential growth, so we are encouraged not to despair, but in fact to redouble our efforts to deliver that exponential growth – it is not yet too late.  There is an underlying assumption that it is essential to recognise.  Delivering on our mandated Net Zero targets cannot be achieved by Gross Zero – so there must be a negative in the carbon balance equation.  CCS is the only technology that can be delivered at the scale needed to deliver the required removal of CO2 from the surface.”


Prof Peter Styring, Professor of Chemical Engineering and Chemistry, University of Sheffield, said:

“This is an interesting paper, however there is a long way to go from technology deployment to reaching capacity.  In a time where capacity and reality are under the microscope this is an important distinction.

“Current deployment of CCS technologies, including enhanced oil recovery, stands at around 40 Mt per year whereas emissions of CO2 are around 37 Gt annually: three orders of magnitude higher.  The paper makes predictions of exponential growth in capture but the graphs suggest this is linear and anyway the error bars are huge.  The missing comparative component is the cumulative CO2 emissions over the same period which show significant divergence away from a net zero scenario.

“It is true that CCS will play an essential role in the drive to achieving the needs of the post-Paris agreement laid out by the IPCC.  However, there needs to be a fundamental technology change in the ways we achieve capture at scale, and importantly at a realistically low economic penalty.  Much of the world’s climate change ambitions rely on carbon dioxide mitigation.  The best way to achieve that is not to burn fossil fuels, however while that technology persists CCUS technologies must be rolled out at scale.”


Prof Myles Allen, Professor of Geosystem Science, University of Oxford, said:

“It is now pretty much universally accepted, except by die-hard Pollyannas on both sides of the climate debate, that we will generate more carbon dioxide over the course of this century than we can afford to dump in the atmosphere and still meet our climate goals.  So the main question for climate policy must be what we do with the excess.  The good news, from this paper, is that there is a solution.  The bad news is that CO2 capture and disposal is still completely dependent on public money, which will be in short supply over the coming decade.  We have to work out other ways of scaling it up.”


Prof Jon Gibbins, Director of the UK CCS Research Centre and Professor of CCS, University of Sheffield, said:

“This paper provides an interesting illustration of full life cycles for CCS, even though we have barely started to deploy it.  This is a much more realistic approach than many scenarios which terminate in 2100 with CCS, including for net negative emissions, still operating at very high rates.  It emphasises the central role for CCS in tackling climate change and the availability of enough secure CO2 storage capacity to solve the problem.  Also that, provided CCS is deployed rapidly, the current climate disturbance can be stabilised successfully over a century or so, a similar time period to that of the fossil-powered Industrial Revolution that has caused it.

“We ideally need net 100% CCS for any fossil carbon removed from the ground (so mainly fuels and limestone for cement) before cumulative CO2 emissions have reached critical levels.

“But most of the IPCC 1.5 degree scenarios include the assessment that CCS is not deployed in time to do this and that other measures cannot compensate so that CCS (in other variations, but still using secure geological storage for the captured CO2) also has to be deployed retrospectively after 2050 to capture the fossil CO2 from the air, and also from the ocean as it re-equilibrates with falling atmospheric CO2 concentrations.  But they still eventually deliver 100% net CCS for all fossil C extracted and a tolerable cumulative total historic net GHG emissions.

“CCS is the specific remedy for a climate problem caused by the human race making a step-change in the way it lives, powered by fossil fuels.  But both the Industrial Revolution, and the remedy, will be relatively short-lived episodes in human history at the multi-millennial level – provided we actually do tackle this challenge effectively.

“Unfortunately a lot of people are still focused on delivering solutions to what was perceived as the previous threat arising from our reliance on fossil fuels – “What do we do when fossil fuels run out?”, having been frightened by the short-term consequences of imbalances between oil supply and demand.  These solutions are not likely to work in time to avoid the need for CCS because their basic premise is wrong – we have an immediate climate problem caused by an over-abundance of fossil fuels not a fossil energy shortage.  Once the cumulative emission budget is exceeded CCS becomes an inevitable and undeniable necessity, but it would be better for future generations to get started as soon as possible.”


Dr Steve Smith, Project Manager of the Greenhouse Gas Removal Hub, Smith School for Enterprise & Environment, University of Oxford, said:

“Capturing and storing carbon dioxide has a key role to play in getting our emissions down to zero.  This study assumes that the path of CCS will follow a certain shape, and then uses the data we have from early development to plot its path out to 2100.  There are pretty major uncertainties in doing that, but the conclusion that there is enough storage capacity underground is one we are already fairly confident about.

“What is less clear is whether the good storage is located close enough to the places we want to capture from.  Also, there is no getting around the fact that CCS development has not been easy.  In the early 2000s there were 40 projects planned around the world.  Since then only 13 have materialised.  Governments and industries will need to commit to make this happen, and at the same time we need to be doing all the other easy things to cut our emissions, too.”


Prof Richard Herrington, Head of Earth Sciences Department, Natural History Museum London, said:

“The study is sound, although it is a projection, but clearly suggests that their assessment of the storage capacity will be sufficient to meet the CCS demand to meet the sub 2 degree Celsius scenarios.  It is clear though that incentives will be needed for the power and other industries to stimulate the use of CCS.

“Along with other international bodies, the UK’s Committee on Climate Change acknowledge the need for CCS as a mitigating technology whilst the transition to low carbon technologies gears up.  This new study suggests that the CCS needs are far more modest than previously proposed and are therefore more likely to be able to be delivered.

“Longer term, we need to reduce our burning of carbon to reach a real net zero with the introduction of renewables, thus negating the need for CCS but achieving this, particularly for transport systems, in the time frame available is very challenging.  In the short term, CCS is one of the transitional technologies that can help reduce emissions until we have revolutionised energy systems for industry, transport and domestic users.”


Dr David Barnes, Marine Ecologist specialising in blue carbon and carbon sequestration, British Antarctic Survey, said:

“The growth of low carbon energies such as wind and solar has soared over the last decade, but a major threat to the below 2°C target was perceived lack of progress in CCS.  Thus this report sounds encouraging but as always the devil is in the detail.  It is one thing to have enough space to store near-future needs but another thing to push ahead and utilise this.

“The current period of covid paused travel shows how quickly carbon use can be reduced, and it seems likely some of our travel and other carbon appetites may even be cut back in the medium term.  We should not forget that investment in highly efficient natural environments (e.g. salt marshes) is very cost effective at CCS and multifunctional, not least in meeting biodiversity targets and providing wild space, that society has never appreciated as much as now.  The findings in this paper will be much scrutinised by scientists, policy makers and hopefully industry, but it is likely to prove contentious, but may yet prove to be a positive spark in difficult times.”


Prof Grant Allen, Professor of Atmospheric Physics, University of Manchester, said:

“The study quantifies the potential storage capacity available to CCS and the authors conclude that this could meet the sink needed to meet IPCC warming limits.  It also describes some promising progress with CCS technology and its application.

“However, the promise of CCS as a silver bullet for offsetting emissions should be considered with caution.  There is a long way to go to test and scale various CCS approaches.  And, as the study concludes, the growth of CCS installed capacity needs to accelerate before it can meaningfully offset emissions, and there is much more work to do to identify suitable storage locations.

“The potential of CCS should not be seen as a reason not to cut carbon emissions now.  There is no guarantee of its success and there is much yet to know.  We should not solely rely on future potential when we should also continue to take action now.  We need to accelerate both actions – carbon capture and emissions reduction.”


Prof Richard Betts, Head of Climate Impacts Research at the Met Office Hadley Centre, and Chair in Climate Impacts at the University of Exeter, said:

“This study focusses on the capacity for storage of CO2 once captured, but it uses IPCC scenarios which also assume increased uptake of carbon via land ecosystems.  This implies a substantial loss of land available for food production, which the IPCC say would pose profound challenges.  So although Carbon Capture and Storage may play an important role in meeting the Paris Agreement targets, it is still not a silver bullet.  It’s crucial to look at it as part of the bigger picture.”


Prof Daniela Schmidt, Professor in the School of Earth Sciences, University of Bristol, said:

“Estimating pore volume of storage of CO2 in former oil and gas fields is notoriously complicated as minerals grow and voids collapse after the oil and gas has been removed.  Only a small number of large scale test sites exist around the world.  As radical mitigation though is fundamental to achieving climate targets, and yesterday’s news highlighted how much change is needed to reduce our emissions, CCS is an important approach.

“This paper estimates how much storage of CO2 is available and how much storage we might need given emission pathways.  There is a vast uncertainty in both of these estimates, but what the paper clearly shows is the need for rapid action.  Acting in the face of uncertainty by building capacity in unconventional storage such as aquifers and rocks now will give us an instrument in hand to reduce CO2 and hence the impacts on our lives.”



‘Global geologic carbon storage requirements of Q2 climate change mitigation scenarios’ by Christopher Zahasky and Samuel Krevor was published in Energy & Environmental Science on Thursday 21 May 2020.

DOI: 10.1039/d0ee00674b


Declared interests

Prof Stuart Haszeldine: “Haszeldine is funded by EPSRC and by NERC to assess CO2 storage.  There are no commercial interests.”

Dr Greg Mutch: “I do not work directly with the authors of this paper, but I am actively working in the wider area of research and campaign for the take up of these technologies as I believe they will be of central important to protect our environment.”

Miles Seaman: “None.”

Prof Peter Styring: “None.”

Prof Jon Gibbins: “The UKCCSRC co-funded the work but I was not involved in it myself, nor directly in selecting this project for funding.”

Dr Steve Smith: “Nothing to declare.”

Prof Richard Herrington: “No conflicts.”

Prof Daniela Schmidt: “No competing interest.  IPCC CLA WGII.”

None others received.

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