A new paper by Christine Ehlig-Economides and Michael J. Economides is getting more than a little attention because it claims that CCS (carbon capture and sequestration) is a deeply flawed concept.
The paper’s abstract:
The capture and subsequent geologic sequestration of CO2 has been central to plans for managing CO2 produced by the combustion of fossil fuels. The magnitude of the task is overwhelming in both physical needs and cost, and it entails several components including capture, gathering and injection. The rate of injection per well and the cumulative volume of injection in a particular geologic formation are critical elements of the process.
Published reports on the potential for sequestration fail to address the necessity of storing CO2 in a closed system. Our calculations suggest that the volume of liquid or supercritical CO2 to be disposed cannot exceed more than about 1% of pore space. This will require from 5 to 20 times more underground reservoir volume than has been envisioned by many, and it renders geologic sequestration of CO2 a profoundly non-feasible option for the management of CO2 emissions.
Material balance modeling shows that CO2 injection in the liquid stage (larger mass) obeys an analog of the single phase, liquid material balance, long-established in the petroleum industry for forecasting undersaturated oil recovery. The total volume that can be stored is a function of the initial reservoir pressure, the fracturing pressure of the formation or an adjoining layer, and CO2 and water compressibility and mobility values.
Further, published injection rates, based on displacement mechanisms assuming open aquifer conditions are totally erroneous because they fail to reconcile the fundamental difference between steady state, where the injection rate is constant, and pseudo-steady state where the injection rate will undergo exponential decline if the injection pressure exceeds an allowable value. A limited aquifer indicates a far larger number of required injection wells for a given mass of CO2 to be sequestered and/or a far larger reservoir volume than the former.
The Guardian’s coverage says::
A new research paper from American academics is threatening to blow a hole in growing political support for carbon capture and storage as a weapon in the fight against global warming.
The document from Houston University claims that governments wanting to use CCS have overestimated its value and says it would take a reservoir the size of a small US state to hold the CO2 produced by one power station.
Previous modelling has hugely underestimated the space needed to store CO2 because it was based on the “totally erroneous” premise that the pressure feeding the carbon into the rock structures would be constant, argues Michael Economides, professor of chemical engineering at Houston, and his co-author Christene Ehlig-Economides, professor of energy engineering at Texas A&M University
“It is like putting a bicycle pump up against a wall. It would be hard to inject CO2 into a closed system without eventually producing so much pressure that it fractured the rock and allowed the carbon to migrate to other zones and possibly escape to the surface,” Economides said.
The paper concludes that CCS “is not a practical means to provide any substantive reduction in CO2 emissions, although it has been repeatedly presented as such by others.”
…
The British Geological Survey confirmed it was looking at the Economides findings and was hoping to shortly produce a peer-reviewed analysis.
Economides, who has a PHD from Stanford University, said he had seen the arguments against his paper from the API and dismissed them as “nonsense” saying vested interests are protecting a new concept foisted on the world by geologists without proper thought.
“I was a [practising] petroleum engineer for many years and soon realised that geologists did not understand flow and the laws of physics, against which you can’t argue.”
Chapman pointed out that Statoil, a Norwegian oil company, had been injecting CO2 into an old reservoir on the North Sea Sleipner field for some time as a successful experiment in carbon storage. But Economides says the Sleipner scheme involved a million tonnes over three years, while one 500mW commercial station would need to absorb and store 3m tonnes annually for 25 years.Economides, who admits he veers towards being something of a climate change sceptic, says the oil and coal industries see these schemes as potential solutions so they can keep on doing what they have been doing in the past, but “CCS is the last refuge of the scoundrel,” he said.
A man who is “something of a climate sceptic” throws rocks at geologists and claims to have figured out why the only lifeline the fossil fuel industry has is frayed to the point of breaking before it’s even used? Fire up the microwave and make a big ol’ bowl of popcorn. This one is going to be a show.
The paper itself is here [PDF].
Another article on CCS (Carbon: from pollutant to potential resource), from December, contains this passage:
As Robert Kunzig and Wallace Broecker point out in their book, Fixing Climate, Carbon Capture and Storage would mean landfill on a ‘stupifying’ scale:
‘If the twenty-nine gigatons produced by the world’s fossil-fuel burning in a single year were liquefied and spread over Manhatten, they would bury the island to about the eighty-fifth floor of the Empire State Building.’
Frank Zeman, from the Department of Earth and Environmental Engineering at Columbia University says we have not yet even started to address the huge issues involved with disposing of carbon.
‘We already have a huge waste problem: imagine what it is going to be like with CO2 as well. It’ll be nimbyism.’
I’ve long thought that the primary roadblock to CCS’ becoming a major tool in addressing the climate change mess was economics. Assume we find exactly the right kind of geologic formations to serve as CCS reservoirs, so we can dismiss all of the issues related to the sheer volume of CO2 to be stored as mentioned above. Just in the US alone, you still have to retrofit 1,445 coal generators at 599 plants, plus 5,467 natural gas generators at 1,653 plants with CCS hardware.[1] And none of those plants was designed with such a retrofit in mind, which will only make the task much more difficult (read: expensive). On top of that, we need an entirely new network of pipelines to carry the CO2 from those existing power plants to the sequestration sites. Just as the plants were not designed with CCS in mind, they were not sited to minimize the cost of removing captured CO2. Think those pipelines will be cheap, especially when the urgency of our climate situation becomes ever more apparent in the next five to ten years, and we have to either shut down some of those plants or implement CCS as soon as possible?
While the paper mentioned above might indeed prove to be right — there could be some very serious physical limitations to CCS that have been overlooked, and I’m certainly no making any judgments either way — I think there’s a much stronger case to be made about the cost of widespread CCS use for existing plants. Everyone talks about a CCS coal plant requiring about 30% more coal to generate the same amount of electricity as a non-CCS plant[2], but it’s a huge (albeit understandable) mistake to assume that 30% is therefore the final cost increment for a full CCS rollout.
And if you want to use CCS only for new, conveniently sited plants, then we still need a solution for those hundreds of coal and natural gas plants cranking away in the US and dumping over 2.3 billion metric tons of CO2 into the air every year, combined. When you have a workable and affordable solution for that part of the problem, please contact the US Department of Energy. I suspect they’ll be quite happy to take your call.
[1] See Electric Power Annual – Count of Electric Power Industry Power Plants, by Sector, by Predominant Energy Sources within Plant and Electric Power Annual – Existing Capacity by Energy Source.
[2] This 30% is due to the additional energy needed to drive the CCS process itself. I have no reason to doubt this number’s accuracy; my point is that it describes just part of the entire infrastructure change needed for a full CCS implementation. Imagine you discover a new fuel for cars that will reduce their CO2 emissions by 90 to 95%. Great news, right? You get about 30% fewer MPG at the same cost per gallon of fuel, and it costs a lot to convert an existing car to use the new fuel, but that ignores the fact that the fuel can’t be transported in any existing pipelines — you need to build an entirely new distribution network that covers the US. Ignoring that last part, in terms of both cost and time, is a huge mistake.
I have thought about this a lot since I first posted a link to it several weeks ago. It is really simple – CO2 goes to a liquid state at about 900 PSI, and if you think about compressing a liquid, well, you just about cannot do it to any appreciable extent.
Economides has had a lot of very accurate predictions, and he, or he and his wife, have used a really thoughtful approach to the CCS problem. CO2 is good for flooding some oil reservoirs because the miscibility of CO2 can be made to mimic that of some crude oils by adjusting the pressure at which it is injected. One proposed flood with which I am familiar is planning to use 3500 PSI injection pressure – and I don’t know if they will be able to permit it at that pressure. The result will be a flushing a higher portion of the oil out of the formation itself, something that is not accomplished by other methods. In situations where it cannot be used, well, so much for technology saving us.
There is another problem with CO2 – it creates enormous corrosion problems.
The end of our current standard of living is nigh.
Now that’s just great! I always thought CCS was a boondoggle, I just assumed they were underestimating costs by a huge factor, not the physics of it.
At the end of the day someone will figure out a way to take atmospheric CO2 and turn it into coal (which we know can be buried safely over geologic time) but it will take massive amounts of energy (and technology) to do in human timescales…or we could just leave the coal in the ground…
First, whoever publicized the paper by “Houston University” needs to take another look at the paper. The lead author is associated with Texas A&M, and the correct name of the Bayou City education institution is “University of Houston.” Also notable is that correspondence is directed to the authors’ consulting firm rather than university email address, suggesting some kind of private sector funding for this project.
While this finding is likely to have us all a-twitter, this is precisely the kind of journal publication that we should take a pause and deep breath at. There will be plenty of academic discussion of this finding before the outcome (if any) should be of policy consideration one way or the other.
Mr. Wilson’s suggestion that “we should take a pause and deep breath” is right on target. The Ehlig-Economides paper is just one of many, and by far, most of the many do not reach such dire conclusions regarding the fundamental physics of the potential for geological sequestration to accept significant volumes of pressurized CO2. The authors of this paper have a thin record of looking at geological sequestration, in comparison to a number of others who have studied this in detail and who do not agree with the paper’s findings. The academic discussions that will inevitably follow will do much to shed light on the viability of geological sequestration.
The viability of CCS more broadly, particularly at levels that are foreseen by many in the policy community, remains an open question for a variety of reasons. Costs (a surrogate for the technical difficulty of capturing CO2), suitability of carbon capture as a retrofit technology, and availability of sequestration sites (particularly in China and India) are critical questions that have not yet been resolved to the point where CCS can be considered to be ready for prime time.
Dr. (Mr.) Economides set up that news and consulting service because of his expertise in oil and gas matters. He may not know everything about CO2, CCS and the other climate matters we fret about here, but he is an expert in oil and gas, particularly in the area of fracing and cementing. To become an expert in those areas, he had to become very knowledgeable about various formations. Hydraulics is what he is talking about here. The ability to compress most liquids is very limited – I think I read 1% but I may be mistaken. Therefor, when you fill a reservoir with that liquid and it bursts, it is no longer a reservoir. Maybe it will take a longer period of time and maybe a shorter period than he projects, but it is going to fill up and when the reservoir fills at approximately the pressure it takes to reach a maximum frac, and the surrounding formations start to break down, it is no longer sequestered.
I have long admired Economides – and he has a remarkable history of accuracy. I would guess that his wife did most of the leg work, but that is the way most of that research takes place. In any case, I do know that it takes about 7 times the energy (when it is done with a electric motors) to compress natural gas to 900 PSI than it does to compress it to 300 PSI, so even taking CO2 to a liquid will be enormously expensive. I will assume that CO2 is comparable, if comparable equipment is used. – Wiki has CO2 becoming a liquid at 870 PSI, btw.
Economides does not accept peak oil, like many of his counterparts in the industry, and he is correct in absolute terms, at least in today’s world. However, I do not think that oil which costs in excess of today’s market to produce will ever see the light of day, since we all know that we are talking about economically producible oil – or cheap oil.
I read the paper by the Economides that you are talking about. The erroneous basis for their calculations is that no wells are drilled to remove the ground water displaced by the stored carbon dioxide “carbon dioxide sequestration is not generally envisioned to be associated with any production of underground fluids,”
Their paper is proof, if proof were needed, that relief wells will be required for many geological structures. Others have discussed the issues that these relief wells might raise. See http://scienceblogs.com/highlyallochthonous/2010/02/carbon_capture_and_storage.php
Jem: Thanks for the comment about relief wells. I hope you’re right and the basic conclusion of the paper is wrong, because if we can’t make CCS work we’re in more trouble than most of us can possibly imagine.