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Energy and Climate Change Committee Inquiry: Carbon Capture and Storage

The Energy and Climate Change Committee has launched an inquiry into Carbon Capture and Storage. The submission produced by the Geological Society and the Petroleum Exploration Society of Great Britain can be found below.

You can read the terms of reference and associated documents on the committee website

Submitted 6 September 2013

1. This submission has been produced jointly by the Geological Society of London and the Petroleum Exploration Society of Great Britain:
i. The Geological Society of London (GSL) is the national learned and professional body for geoscience, with over 10,500 Fellows (members) worldwide. The Fellowship encompasses those working in industry, academia and government, with a wide range of perspectives and views on policy-relevant geoscience, and the Society is a leading communicator of this science to government bodies and other non-technical audiences.
ii. The Petroleum Exploration Society of Great Britain (PESGB) represents the national community of Earth scientists working in the oil and gas industry, with over 5,000 members worldwide. The objective of the Society is to promote, for the public benefit, education in the scientific and technical aspects of petroleum exploration. To achieve this objective the PESGB makes regular charitable disbursements, holds monthly lecture meetings in London and Aberdeen and both organises and sponsors other conferences, seminars, workshops, field trips and publications.

2. Since the start of 2011, our two organisations have worked together when appropriate in communicating with the government, parliamentary committees and others on matters relating to petroleum geoscience. Both our organisations routinely bring together the best geoscientists from across academia, industry and government to exchange and debate research findings, through scientific meetings and publications. Commercial scale development and widespread implementation of carbon capture and storage (CCS) will depend on the engagement, expertise and experience of the petroleum geoscience community, as well as geoscientists from a range of other specialisms.

3. Our submission draws principally on the geoscience relating to carbon capture and storage, as well as addressing some of the interfaces between geoscientific and other factors (e.g. economic geology) and the professional experience of geoscientists. Some of the questions set out in the call for evidence are outside the competence of the GSL and PESGB, and we have not attempted to answer these.

What types of CCS technology are currently being developed and how do they differ from one another?

4. This question most obviously refers to the range of potential technologies for capturing carbon emissions (at source or from the atmosphere), infrastructural innovations, etc. Others are better placed to comment on these aspects of technology than we are. But it may also be helpful to think of the range of possible geological settings in which CO2 might be stored, together with the mechanisms by which CO2 would be trapped in these settings, as more or less well-developed ‘technologies’.

5. CO2 storage in depleted oil and gas reservoirs: Hydrocarbon reservoirs are typically formed when oil or gas migrates upwards from the source rock in which it was created, due to its buoyancy relative to the water in the pore space within the rock, until it reaches a structural or stratigraphic ‘trap’, where a porous rock is overlain by an impermeable ‘cap rock’. Once much of the oil or gas has been extracted from a reservoir, supercritical CO2 (a fluid sharing properties with both gases and liquids) is injected into the porous rock. Like the hydrocarbons, it is buoyant relative to the water in the pore space in the rock, and most of it migrates upwards as a ‘plume’ until it is stopped by the impermeable cap rock (buoyancy trapping). Some is left behind, trapped in small quantities in the pores by capillary pressure (residual trapping). Over time, the mixture of phases in which CO2 is present will vary. ‘Free phase’ CO2, immiscible with the water in the reservoir rock, will usually dominate initially (up to 100 years, say). Over longer timescales, some will dissolve into the water in the pore space (dissolution), and some will become attached to the rock surface (adsorption) or chemically react with it to make new minerals (mineralisation). The efficacy of this methodology for carbon storage is well-established, and there is a high level of knowledge regarding the long term behaviour of CO2 in such environments, though research in this area is ongoing, particularly into circumstances where dissolution, adsorption and mineralisation may happen more rapidly than classical models suggest. (This is advantageous because these trapping mechanisms lock the CO2 into the subsurface more securely.) The depleted oil and gas fields of the North Sea provide the UK with extensive and well-characterised potential storage capacity.

6. CO2 storage with Enhanced Oil Recovery (EOR): A number of techniques can be used to increase the amount of oil or gas which can be recovered from a reservoir. The injection of CO2 to do this is not new, and the decades of experience of this technique in the oil industry, particularly in the US, is one of the main sources of knowledge about the behaviour of CO2 in such geological settings on which the concept of CCS has been proven. Commercial scale projects integrating CCS and EOR are now underway (again, principally in North America). The economics of CCS is potentially much more attractive when combined with EOR, because of the return from increased hydrocarbon yields. Some have questioned its value for abatement of carbon emissions, because while it can lead to disposal of substantial amounts of CO2, this may be offset by the emissions from use of the additional hydrocarbons extracted unless these are also captured. But CCS with EOR provides a potential pathway for extensive commercial investment in CCS, leading to development and scaling up of capacity and infrastructure, and to ‘learning by doing’ at scale – both essential to bringing down the costs of CCS (with or without EOR) and accelerating its deployment.

7. Storage in closed saline aquifers: These geological settings are similar to oil and gas reservoirs, with a porous host rock overlain by an impermeable cap rock, but are not the site of hydrocarbon deposits. CO2 injected into such formations is subject to similar trapping mechanisms, and its efficacy is well-established. The potential storage capacity provided by closed saline aquifers is much greater than in hydrocarbon reservoirs, but they have been much less explored and characterised. In particular, while the presence of oil or gas in a stratigraphic or structural trap goes a long way towards demonstrating the integrity of the cap rock (because this is what has caused hydrocarbons to accumulate and be retained there over geological time), this is not the case for saline aquifers. More work is therefore likely to be required to characterise potential sites, in order to have confidence that the CO2 will remain in the formation after injection.

8. In addition to the ‘conventional’ storage technologies outlined above, other technologies are at an earlier stage of development and demonstration. Their potential to provide practicable and affordable storage is therefore less certain, but it may be very significant:

9. Migration-assisted trapping in open saline aquifers: In these settings, there is no cap rock. Rather, the geology is such that the CO2 moves through the formation only very slowly, and is prevented from escaping by residual trapping in the pore spaces (and later by dissolution, adsorption and mineralisation). If current research can demonstrate the efficacy of this approach at scale, it potentially opens up very significant further storage capacity and extends the range of geologies in which CO2 can be stored (reducing the need to transport it to a site meeting more restricted geological criteria, such as a depleted reservoir). Understanding better the rates at which dissolution, adsorption and mineralisation occur is key to demonstrating this model.

10. Mineral trapping in mafic rocks: Research is underway to test injection of CO2 into mafic rocks (rocks with high magnesium and iron content) such as basalt, which are very widespread. Being basic (rather than acidic), such rocks are more reactive with CO2, which may therefore be trapped rapidly by mineralisation – a process which in conventional carbon storage settings will typically occur over thousands of years. Again, if this approach comes to fruition it may widen the range of geologies in which CO2 can be stored, and provide extensive further storage capacity. Further possibilities are carbonation of ultramafic mine tailings and sediments, and mineral trapping in certain soils.

11. In April 2014, GSL and the European section of the American Association of Petroleum Geologists (AAPG) will hold the third in a series of joint conferences on CCS. This will focus on the range of conventional and unconventional geologies and models for carbon storage, and their potential to contribute to the CO2 storage capacity which will be required globally to meet emissions targets.

12. The length of this submission and the time available do not permit a fuller technical explanation of the geology of carbon storage, or of the interrelationship of various injection techniques and the geological settings/trapping mechanisms outlined above. The March 2010 report to DECC ‘CO2 Storage in the UK – Industry Potential’ ( provides some further detail, although it does not address unconventional models in any depth. It is also written in a technical style and is not easy for non-specialist readers to understand. We would be pleased to provide further briefing materials or presentations on the relevant geology.

What contribution could CCS make towards the UK’s decarbonisation targets? Are the UK Government’s expectations reasonable in this regard?

13. CCS can make a very significant contribution to meeting these targets. This is impossible to quantify, as it depends on a wide range of political, economic and technical factors which will shape the UK’s mix of energy sources and carbon emission abatement measures. As decarbonisation targets become more stringent, CCS will become a necessity, given that we will continue to be dependent on fossil fuels for a significant part of our energy needs for several decades at least, however rapidly we deploy other low-carbon technologies.

Are there any potential benefits (e.g. the ability to export CCS technology abroad) of successfully developing CCS to the UK economy and, if so, what are they?

14. The UK has extensive potential storage capacity under the North Sea, combined with a strong research base and a history of academic/industry collaboration in the offshore oil and gas sector. These advantages have the potential to help the UK take a leading role in developing a global CCS industry, bringing the opportunity to export UK expertise and services, but they will be lost unless this is done quickly. Several other countries are making rapid progress with implementation of CCS, notably the US and China. UK CCS researchers are currently in demand internationally, particularly in regard to novel geological storage settings and mechanisms.

15. Our storage capacity is a potentially significant asset, especially given the likely greater social constraints on onshore storage which may be available in other European countries, but the restriction on importing CO2 limits the opportunity to exploit this. The UK is also well-placed to test injection into suitable geological settings onshore compared with other European countries, in order to test fluid behaviour and its monitoring – this would be likely to arouse greater public concern than offshore storage. The cost of such research would be relatively modest, and could stimulate development of SMEs well-positioned to exploit commercial opportunities internationally, as well as helping to maintain the UK’s research leadership position.

What are the main barriers (e.g. economic, political, regulatory, scientific and social) to developing large-scale integrated CCS projects in the UK and internationally? How can they be overcome?

16. The imperative to implement CCS at scale, nationally and globally, is reflected in government’s commitment to the central role it must play in the UK’s energy system in the coming decades, as stated in its CCS Roadmap. Confusingly, elsewhere in the CCS Roadmap, government says that CCS will only be implemented at scale if this can be done economically. Given their acceptance of the necessity of CCS, it is therefore essential that government develops and clearly sets out an economic and political framework to achieve its rapid and widespread implementation. It is outside our remit to comment on how this would best be done, but the geological community has a strong interest in seeing such a framework explicitly set out, because geoscientists will be key to delivering CCS at scale. We note that the North Sea oil and gas industry did not arise spontaneously under prevailing market conditions – rather, considerable design and investment on the part of government, and the development of effective partnerships with industry, were key to its success.

17. Although research into CCS is ongoing – to underpin its deployment, to grow confidence in it and to explore novel technologies – the state of scientific and technical understanding is sufficient to proceed with implementation. This will lead to learning and reduction of uncertainty as a result of practical experience, as well as development of infrastructure, thereby reducing costs and stimulating investment. Such ‘learning by doing’ should in turn inform future R&D.

18. A key rate-limiting step in implementing CCS is likely to be the development of storage capacity. This will depend on considerable geological work being done – exploration for suitable geological settings, and characterisation of host rocks, cap rocks and overburdens (the rock above the cap rock) to give confidence not only that CO2 can successfully be injected, but that we have sufficient understanding of how it will behave over time to meet technical, regulatory and societal requirements. (Equivalent work would have to be done in unconventional storage settings.) While engineering techniques may be developed internationally, development of storage capacity will be specific to each country, so we will not be able to depend on work done elsewhere.

19. In submissions to previous inquiries conducted by the Committee (e.g. ‘The Impact of Shale Gas on Energy Markets’, October 2012), we have highlighted the distinction between hydrocarbon resources and reserves. ‘Resource’ is the amount in the ground, while ‘reserves’ refers to the amount which can be economically extracted using current technologies and under current regulatory regimes, which depends on cost of extraction and market price. Similarly, it may be helpful to think of pore space for CO2 storage in terms of resources and reserves. The amount of theoretically available pore space (the resource) is huge – but that which is technically, economically and socially feasible to use (reserves) will be much more limited, and dependent on carbon price, implementation costs, regulatory framework, etc, as well as geological characterisation.

20. To stimulate the development of storage capacity at a national level, careful thought should be given to appropriate sharing of data between commercial operators, the British Geological Survey, DECC and other actors, in order to maximise collective benefits without inhibiting commercial competitiveness. Such data sharing regimes are long-established with regard to hydrocarbons exploration and production.

21. If implementation of CCS at scale is left too long, there may be significant missed opportunities due to the decommissioning of North Sea infrastructure in fields where hydrocarbon production is coming to an end, some of which would also be of use for CO2 storage. Furthermore, greater clarity on the part of government will be required if combined CCS and EOR is to play a role in the UK (setting out the tax regime and regulatory framework, for example), to allow operators to plan ahead and make investment decisions with confidence. This could extend the lifetime of the North Sea hydrocarbons industry, and help develop infrastructure and know-how for CCS. If this is to come to fruition, more effective coordination will be needed across government – and indeed within DECC, between the Office of CCS and the hydrocarbons licensing team.

22. The issue of public acceptance and confidence is hardly addressed in the government’s CCS Roadmap. In the case of offshore storage, public concerns about the injection and long-term behaviour of CO2 on safety grounds are likely to be minimal, although it will still be important to win public confidence in CCS as a means of abating carbon emissions (as well as addressing any concerns about the capture and transport of CO2, which will usually happen onshore). If any CO2 is to be stored in onshore geological settings (whether for R&D purposes or at commercial scale), these concerns are likely to be much greater. Developing public confidence in and acceptance of CCS will depend in large part on effective communication of the relevant geoscience. Learned and professional scientific bodies have a vital role to play in communicating science in such contested areas, as they bring together those from industry and government with hands-on project experience and information with those from academia who may attract higher levels of public trust. GSL is organising a conference in mid-2014 on strategies for public engagement in areas of contested geoscience, focusing on radioactive waste disposal, shale gas and CCS. We will keep the Committee informed about this event.

23. In seeking to establish public, political and investor confidence in CCS, it is important to recognise that there will inevitably be some level of CO2 leakage from geological storage. This need not jeopardise the effectiveness of CCS, and should not be allowed to undermine confidence in it. The challenge is to understand, manage and regulate leakage so as to meet several objectives, and to communicate transparently how this is being done:
  • Safety issues are paramount, and are addressed below.
  • To justify implementation of CCS on political and economic grounds, it is important that a high proportion of injected CO2 is retained in geological storage. But judgments about the level of leakage which is considered acceptable over a given timescale should recognise CCS as a transitional technology to gain us time to genuinely decarbonise our economy over the next 50-100 years, rather than as a permanent solution. It is far preferable that CCS be implemented at scale as rapidly as possible, with the great majority (but not 100%) of the CO2 injected into geological formations being retained, rather than allow unabated carbon emissions to the atmosphere to continue.
  • Uncertainty regarding understanding of and consequences of CO2 leakage may deter companies’ willingness to invest in CCS. So it is vital that R&D in this area continues, that improvements in this understanding are clearly communicated, and that monitoring and regulatory regimes are designed with this understanding in mind, alongside public safety and confidence. There must also be clarity as to who has responsibility for the long-term fate of injected CO2. Some of our members have suggested that the limit on leakage levels mandated in the European Commission CCS Directive are both unachievable (being at a level which is hard to detect) and unnecessary (having no scientific basis). If this assertion is correct, there is a risk that the cost of CCS will be artificially inflated, and that investment will be deterred.

Are there any safety issues associated with capturing, transporting and storing carbon dioxide? How could they be overcome? Who should have responsibility for ensuring these activities are safe?

24. As noted above, a degree of leakage of CO2 from geological storage is to be expected. Natural instances of CO2 leakage, such as occurs in some areas of Italy, show that this can be managed safely. CO2 is not poisonous, but it is heavier than air, and so can cause suffocation if it collects in low-lying areas. Regulation should be designed with this in mind.

25. Low levels of induced seismicity will result whenever large volumes of fluid are injected into rock, whether in carbon capture and storage (CCS), geothermal energy generation or shale gas extraction. Many other operations which disturb the geosphere (e.g. drilling, mining) can also induce micro-seismicity. This is well known and understood in the hydrocarbons industry, which is experienced in its effective management. Operating companies routinely draw on background knowledge derived from other applications in order to identify relevant uncertainties and to minimise and manage such risks, such as in planning well locations to avoid significant faulted or unstable zones. The same factors should be considered when siting and planning CO2 disposal. In particular, any injections close to faults would need to be monitored carefully.

Could the successful development of CCS improve international efforts to mitigate climate change? What role could UK CCS play in this?

26. As noted above, CCS has the potential to contribute significantly to UK’s decarbonisation targets, and will become a necessity as these become tighter, in the context of continuing use of fossil fuels, as UK government has recognised. The same applies globally, in which context continued dependence on fossil fuels is likely to be even stronger, given the plentiful and cheap supplies available in the US, China, India and elsewhere. We have also suggested above some of the ways in which the UK has the potential to provide leadership for wider implementation of CCS, and opportunities this might afford the UK.

What are the consequences of failing to develop CCS and what alternatives are available for decarbonisation if CCS fails?

27. The geological record contains abundant evidence, independent of climate modelling, of the consequences of releasing significant amounts of carbon into our atmosphere (see The atmosphere and oceans warm, especially near the poles, sea-levels rise, the oceans become more acidic and less well oxygenated, and many species become extinct.

28. The principal danger is not that CCS will fail – it is technically proven – but that we may fail to implement it (or to do so sufficiently extensively and quickly), both nationally and globally. Pacala and Socolow’s ‘stabilisation wedges’ model of 20041 provides a useful starting point for considering the scale of the challenge which would face us if we were to try to avoid dangerous climate change in the coming decades without extensive worldwide deployment of CCS for emissions from both power generation and heavy industry. Given our continuing dependence on fossil fuels, it is hard to see how the proposed contribution of CCS could be substituted by scaling up other aspects of emission reductions (reforestation, growth of renewables, reduction in energy consumption, etc). However rapidly we move to decarbonise our electricity generation system, fossil fuels are likely to remain part of the energy mix for the foreseeable future due to their dispatchability (flexibility to power up and down rapidly), complementing more intermittent or slower dispatch energy sources. Switching electricity generation in the UK entirely from coal to gas would deliver a limited reduction in emissions, but not nearly enough to meet our emissions targets in the long term. Extensive future use of gas without CCS is not sustainable.

Other comments

29. We would be pleased to discuss further any of the points raised in this submission, to provide additional information, or to suggest oral witnesses and other specialist contacts.


1. Pacala, S. and Socolow, R. (2004). Stabilisation wedges: solving the climate problem for the next 50 years with current technologies. Science, 305, pp 968-972. Available online at: