Scientists claim success in burying carbon – experts respond

Australian scientists are claiming success following completion of a New Zealand-backed pilot carbon capture and storage project that saw thousands of tonnes of carbon-rich gas pumped underground.

However, New Zealand experts are divided on the usefulness of the geoengineering solution to cut growing emissions both in New Zealand and overseas.

The CO2CRC Otway project pumped over 65,000 tonnes of CO2-rich gas two kilometres underground into a depleted natural gas reservoir in the Otway basin in Southwest Victoria, Australia.

The results of the project’s monitoring to date are published today in the journal Proceedings of the National Academy of Sciences.

Registered journalists can log in to the SMC Resource Library to access the paper, photos and further press material.

The authors of the article conclude:

“The CO2CRC Otway Project has demonstrated that the storage of CO2 in a depleted gas field can be designed and safely achieved. Monitoring showed that there has been no measurable effect of stored CO2 on soil, groundwater, or atmosphere. Good relations with the local community, and decision makers at various levels of government, were established and maintained.”

“Overall the project shows that our level of knowledge of subsurface processes involving CO2, and our ability to forecast its behavior, is adequate to proceed with large-scale geological storage of CO2 in depleted gas fields, and the capacity of these structures could be of global significance for carbon capture and storage.”

A 2009 explanatory video from the Otway Project can be viewed at left. The Otway project, which is partly funded by New Zealand’s Ministry of Science and Innovation and the state-owned enterprise Solid Energy, also explored wider social issues that could arise from carbon sequestration, with community engagement playing a large role in the initiative.

Solid Energy has interests in using carbon sequestration to lower emissions from New Zealand projects such as the planned lignite processing plant in Southland.

Quick facts:

  • 65,445 tonnes of CO2-rich gas  were injected into a depleted natural gas well
  • The well is 2,003-2,014 meters below sea level
  • Pumping took place between March 2008 and August 2009
  • 500kg of CO2 are stored per cubic metre

The Science Media Centre contacted local experts for further comment on the project and the implications for New Zealand.

Feel free to use these quotes in your reporting. To talk to a local expert on carbon capture and storage, please contact the SMC ( 04 499 5476;

Brad Field, Geologist, GNS Science

“The Otway project has indeed demonstrated that safe and effective storage can occur in a depleted reservoir, and its results offer key lessons for other sites, present and future, particularly in the area of monitoring.  Even tiny natural diurnal variations in CO2 in soil have been characterised at Otway, in parts per million, taking monitoring to a very high degree. The key distinguishing feature of the Otway project is the intense research that has been done before, during and after storage.  The aim of Otway is to conduct research on the topic and it has become a world leader in this area.

“Carbon capture and storage (CCS) is regarded by the International Panel on Climate Change as an essential element of how we mitigate climate change – part of a set of measures that includes development of cost-effective renewables.  CCS was recognised last week by the United Nations meeting in Durban as an important tool in the fight to reduce global warming.  Countries will continue to burn fossil fuels for many years to come – it’s a fact of life – but fortunately CCS provides a powerful method to directly reduce these anthropogenic emissions.  We were hoping to limit the global rise in temperature to 2 degrees by the year 2100 but that’s proven too difficult and the target’s been revised to 3.5 degrees.  If we continue as we are it might be 6 degrees of global warming, which would be very nasty!

“When talking about CCS it helps to make a clear distinction between CCS, which is carbon capture and storage, and the underground storage of carbon (“USC”), which is only a part of CCS.  The issues and benefits of carbon capture are quite different to those of USC.

“The capture side of CCS can be viewed as consisting of two broad categories.  Firstly, some natural gas has high percentages of carbon dioxide which may need to be removed before use.  The extraction or capture of carbon dioxide from natural gas has been well established for many years.  It’s already being done in New Zealand on gas from Kapuni, and will be done on a larger scale as part of the Gorgon project in Australia.

“Secondly, there’s capture from thermal power stations.  This is still in its early days of development and although it is possible, it has not yet been economic to do so.  Early difficulties are to be expected in such emerging technologies, and new processes that have greater efficiencies are being discovered every year.  Capture from full scale thermal power stations (or cement or steel works) can be  split further into retrofitting existing plant, and building integrated capture facilities when new power stations are established; each case has its own economics.  For example it is highly unlikely to be economic to retrofit the aging coal thermal station at Huntly but it might well be worth including capture in any new thermal station such as an additional gas turbine.

“Underground storage of carbon dioxide has been underway for decades.  The most common form of USC is injection of carbon dioxide into oil fields to assist the production of more oil.  In this case, enhanced oil recovery (EOR) has an economic benefit.  In the USA there is a shortage of available CO2 and companies are paying up to $100 per tonne for use in EOR.  This might make the capture of CO2 more economically viable, as the CO2 has a commercial use and is likely to foster the development of more efficient capture technology that can be used for non-EOR USC.

“For USC to play its necessary role in climate change mitigation however, requires much larger amounts of CO2 to be stored underground than that from EOR activities.  USC in depleted oil and gas fields is attractive mainly because the storage sites are generally well understood from an extraction (oil and gas) point of view and are therefore cheaper to assess from an injection (or storage) point of view. There are many cases where depleted fields have been used to store natural gas (New Zealand has one example, at the Ahuroa field in Taranaki).

“However, there are differences between storing natural gas and CO2 – for example, CO2 can corrode the cement and casing of pre-existing wells, so old infrastructure might need to be partly replaced or sealed – but injection of gas into depleted fields is not in itself new.  It is economic to inject natural gas at Ahuroa because of a take-or-pay agreement; the economics of UCS might depend more on the level of carbon tax avoided by storage, as well as public or political opposition to thermal stations which lack CCS.  CCS, including USC, will become economically viable in New Zealand when the carbon tax rises, when the cost of capture falls, or when there is a strong desire in New Zealand to not discharge CO2.

“Perhaps the most far-reaching effect of climate change on New Zealand will be immigration from the northern hemisphere, particularly western Europe.  A global increase in temperature of say 3 degrees will not occur uniformly – New Zealand’s average temperature will probably rise less than that of Europe, and the attraction of a clean, green country with lots of space will be strong.  If/when our population doubles our energy demands will soar and natural gas with CCS might be preferable to more large hydro lakes and wind farms, both of which can have significant carbon footprints via the steel and concrete they require and both depend on the weather, which will be changing along with climate change.

“Geothermal will help to meet demand but the immediate future is likely to involve a suite of energy supplies comprising renewables such as wind, hydro, solar and geothermal, as well as fossil fuels combined with CCS.  It is worth noting however that the easiest way to reduce emissions is conservation and greater energy efficiency.

“GNS Science has published several reports on USC options particularly around Taranaki as part of an early screening process, and more regional, broad screening studies have been done for CO2CRC.  A recent report assessed the economics of CCS in Southland with an aim of assessing CCS associated with use of the Southland lignites, though USC in onshore Southland is likely to be relatively limited. There is, however, scope for large-scale USC in Taranaki once fields approach depletion and particularly in offshore areas, where structures tend to be larger and less faulted than areas close to our deformed axial ranges.  Taranaki already has a source of pure CO2 from the Vector gas processing plant, that could be used to start a pilot USC site – preferably one which could be expanded to a large-scale facility if the need arises.

“Public knowledge and opinion are very important in relation to CCS.  The first stages of consultation so far suggest most people do not yet know much about it and this needs to be addressed with wider consultation and discussion.  The provision of facts alone will not suffice – people tend to want open, impartial discussion as well, and that is entirely reasonable.”


Prof Arthur Williamson, Professor Emeritus, Chemical and process Engineering, University of Canterbury comments:

“Carbon capture and storage (CCS) from fossil fuel combustion involves four main steps: separation, concentration, transport and storage. The first two of these could be readily fairly readily achieved in conjunction with large point sources such as thermal power stations using fairly straightforward tested technology chemical processes. The price is a significant increase in plant and a significant increase in fuel consumption per unit electrical energy produced . Transport of  gases in pipelines is a  fairly well established technology. Storage is the least well established step and the one that is in most need of demonstration.

“This paper describes a pilot storage scheme that ran for a period of approximately 2 years during which 65 000 tons of carbon dioxide were injected at a depth of about 2000m and at a density of 500kg m-3 into a formation close to a natural gas well that was providing that gas from which the carbon dioxide was extracted .

“The experimental site appears to have been carefully chosen and the experiment to test the capacity and potential leakage of injected carbon dioxide appears to have been well designed and carefully executed. It shows that a small scale storage operation monitored over a short time appears feasible.

“Although the general tone of the paper is optimistic of the potential for storage there are a number of significant caveats (eg “direct confirmation of containment is difficult because the amount of CO2 is small” and  “IPCC estimates of likely leakage rates would be very hard to confirm” and “detailed calcultions predict that 56-84% 0f the space originally occupied by recoverable CH4 is reoccupied by CO2 .  The trial suggests that while CCS in old natural gas sources or nearby structures may be  possible there is considerable concern that each such possibility will be site specific and each may need to be tested individually.

“The authors comment on the problems of negative perception of CCS and indicate that the Otway results should contribute to allaying concerns.

“My own view is that unlike the initial stages of CCS, storage is critically site specific in both capacity and security. To put the Otway project into context we note that a 1000MW coal fired power station can  produce up to 5 to 10 000 000 tonnes of carbon dioxide per year depending on fuel type and generation efficiency. The energy requirements of  CCS  will, according to our own studies (ref) increase this to up to more than 15 000 000 tonnes per year depending again on the efficiency of the process. Worldwide emissions from electricity generation are estimated to be about 50 billion tonnes per year. This implies that CCS for all power stations will need to be about 1 000 000 times the magnitude of the Otway test.

“In terms of sustainability one of my own views is that technologies that interfere with the environment should be “reversible” in the sense that if they prove to be a bad choice they can be removed and they system returned to its pristine state. CCS fails this test.

“The cost of introduction of CCS either by addition to existing power stations or by replacement of existing power stations with CCS equipped plant is represents an approximate doubling of capital outlay.  At that price we would be better to consider recent renewable systems.

“One  might reasonably assert that the current work on CCS is too little too late and that we would be better employed in working urgently on the avoidance of CO2 emissions from  power generating systems rather than on attempts to deal with them by CCS.”


Dr Ian Mason, Research Fellow in Environmental and Energy Engineering, Department of Civil and Natural Resources Engineering, University of Canterbury comments:

Do you agree with the conclusion, “The CO2CRC Otway Project has demonstrated that the storage of CO2 in a depleted gas field can be designed and safely achieved.”?

“Yes, BUT only for this site and only for the very short time of the survey.”

Is there potential for similar projects to be undertaken in New Zealand, either on land of offshore? 

“Yes, BUT the key question is why would one wish to do this?”

If so, are there particular sites or areas of New Zealand which are better suited, geologically speaking, for such efforts?

“Yes e.g. depleted gas fields such as Maui; BUT certainly not seismically active areas which includes most of NZ.”

Are you aware of any effort to identify such sites in New Zealand?

“Yes, GNS are working on this and some preliminary results are published.”

Does NZ have any regulatory framework that would adequately cover similar projects here?

“The expert on this matter is Prof. Barry Barton at University of Waikato.”

What risk does earthquake activity pose to underground sequestration?

“Potentially extremely serious.”

Could you comment on the economic viability of such projects both in New Zealand and overseas?

“There is very little reliable information publically available, but in general it is expected to be very expensive.  Solid Energy have ruled out a lignite electricity generation plant with CCS on the basis of cost; but appear to believe it economic in conjunction with a lignite to diesel plant.”

Further comments

” 1.      It is important for the public that the key question – “why would anyone want to spend money on such a project in NZ?” – is asked.

One obvious reason is to support Solid Energy’s plans to convert lignite into diesel fuel.  They propose to capture 50% of emissions from their process plant (relying on forestry to account for the other 50%); and they propose to meet any legal requirements, but do no more.  Of course it is impossible for Solid Energy to capture emissions from vehicles.  So at very best this project will achieve NO DECREASE in GHG emissions – at a time when reductions are urgently needed for high emitting countries such as NZ.  In practice, it is likely that emissions will increase by about 10% over current practice.  In addition, emissions accounted for by forestry will not be taken up immediately but will circulate in the atmosphere for many years as trees slowly grow.  Furthermore, there is no guarantee of any benefit to NZ citizens in the form of cheaper fuel or preferential access from converting lignite to diesel here.  It would be fair to assume that this fuel will be sold on the global market to the highest bidder.  The only benefit would be financial but with the impending partial privatisation of SOEs, a lower return will come back to the NZ government.  Since NZ has ample renewable resources, money would be better spent on utilising these sustainable resources and not on a process which will lock us into carbon-based future for many years, whilst achieving no reduction in emissions.

2. The public should be aware that sequestration is very site specific.  It is dangerous to assume as the authors of this paper appear to, that performance at Otway means that CCS can be rolled out satisfactorily world-wide.

3. Some general comments on the paper:

3.1  the statement that fossil fuels will continue to be burned for decades is an opinion not a fact.  Furthermore the reference cited is a weak one in relation to such an opinion – the authors (Pacala and Socolow) are not experts in fossil fuels.  A better source would be the IEA.  We can speculate that the fossil fuel industry will continue to push their products; this a highly probable.

3.2  it is not true that CCS is essential – this again is just an opinion.

3.3  the authors cite no references in their discussion of social opposition to CCS storage sites despite the fact that such literature exists.

3.4  the authors have clearly set out to change public opinion as a primary goal “…noncommercial storage demonstration projects are important in building public confidence…”   only then adding points about scientific understanding and technical capacity.  This seems to be the wrong way round.

4. For CCS to make a meaningful contribution to emissions reduction it must be fitted to the thousands of existing coal-fired electricity plants world-wide.  There is no serious discussion of retro-fitting this very large number of generating plants – which would be very expensive and will rely on suitable sites appropriately located. To date, retrofitting of a electricity generating plant has not happened; nor has a new full-scale electricity generating plant with CCS ever been constructed.

5. Finally, there are credible alternative strategies.  It is important for the NZ public to be aware of the Zero Carbon Australia 2020 report; the Greenpeace “Battle of the grids” study and local work on a 100% renewable electricity system for NZ, for example.”

Dr Shannon Page, Lecturer, Department of Environmental Management, Lincoln University comments:

Do you agree with the conclusion, “The CO2CRC Otway Project has demonstrated that the storage of CO2 in a depleted gas field can be designed and safely achieved.”?

Yes, but with the qualifier “for the Otway Basin”.  Carbon storage is very site specific.  As described in the paper, a number of larger sequestration projects have also been reported in which the CO2 is stored in a natural gas field.  This paper presents the results of storage for the geological formations found in the Otway Basin, as well as the community and regulatory aspects for that area.

Is there potential for similar projects to be undertaken in New Zealand, either on land of offshore?

The Otway project removes CO2 from a naturally occurring underground reservoir, and re-injects the CO2 into a depleted natural gas field located 2km away.  For a similar project to be undertaken in New Zealand, a depleted gas field with known storage potential would have to be located, together with a CO2 source and a pipeline constructed between the two.

If so, are there particular sites or areas of New Zealand which are better suited, geologically speaking, for such efforts?

The gas (and oil) fields in New Zealand are all located in the Taranaki region.  Should carbon storage occur in New Zealand, it would first (and perhaps only) occur in this region.  Detailed geological information, obtained by drilling and well testing, is required to establish the suitability of a storage site.  As much of this information is already obtained via oil and gas exploration, these make the most appropriate sites for storage.   Globally, all major CO2 storage projects involve oil or gas recovery, with the CO2 being injected directly into the field, or an adjacent geological formation.

Are you aware of any efforts to identify such sites in New Zealand?

GNS has looked at existing geological data of New Zealand in order to identify potential storage sites.

Does NZ have any regulatory framework that would adequately cover similar projects here?

This issue has been looked into by the MED.  A report commissioned by the NZCCS partnership has also examined the regulatory framework.  It appears more clarification around the regulatory framework is required for CCS in New Zealand.

What risk does earthquake activity pose to underground sequestration?

Presumably it increases the risk of leakage.  Existing storage sites are either in or around oil and gas fields; sites that have been geologically stable for considerable time.

Could you comment on the economic viability of such projects both in New Zealand and overseas? Will this change over time?

The economic viability of any such project is highly dependent on the project specifics.  The Otway project was a demonstration/research project, funded by various industry and government bodies.  This project was not economic in the sense that it was the least cost method to address CO2 emissions (in fact there was no CO2 reduction; instead, a transfer of CO2 from one underground site to another). This project was economic due to the funding arrangements and research outcomes desired.  Such a project could in theory, be conducted in New Zealand provided an appropriate storage site and CO2 source is found.

For more information contact the SMC ( 04 499 5476;