Carbon capture and storage (CCS) has dug itself into quite a deep hole. Costs remain very, very high (see Harvard study: “Realistic” first-generation CCS costs a whopping $150 per ton of CO2 “” 20 cents per kWh!). And nobody wants the CO2 stored underground anywhere near them (see CCS shocker: “German carbon capture plan has ended with CO2 being pumped directly into the atmosphere”).
Now comes a new study in the Journal of Petroleum Science and Engineering, “Sequestering carbon dioxide in a closed underground volume,” by Christene Ehlig-Economides, professor of energy engineering at Texas A&M, and Michael Economides, professor of chemical engineering at University of Houston. Here are its blunt findings:
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.
The study concludes:
In applying this to a commercial power plant the findings suggest that for a small number of wells the areal extent of the reservoir would be enormous, the size of a small US state. Conversely, for more moderate size reservoirs, still the size of Alaska’s Prudhoe Bay reservoir, and with moderate permeability there would be a need for hundreds of wells. Neither of these bodes well for geological CO2 sequestration and the findings of this work clearly suggest that it is not a practical means to provide any substantive reduction in CO2 emissions, although it has been repeatedly presented as such by others.
Realistically, it has always been hard to see how CCS could be more than a small part of the solution to averting catastrophic climate change, as I discussed at length in my September 2008 post, Is coal with carbon capture and storage a core climate solution?
We need to put in place 12 to 14 “stabilization wedges” by mid-century to avoid a multitude of catastrophic climate impact “” see “How the world can (and will) stabilize at 350 to 450 ppm: The full global warming solution (updated)” For CCS to be even one of those would require a flow of CO2 into the ground equal to the current flow of oil out of the ground. That would require, by itself, re-creating the equivalent of the planet’s entire oil delivery infrastructure, no mean feat.
But any significant amount of leakage would render CCS pointless. The UK Guardian‘s article on the study quotes the coauthor:
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 Guardian talked to “The Carbon Capture and Storage Association (CCSA), which lobbies on behalf of the sector”:
Jeff Chapman, chief executive of the CCSA, believes Economides has made inappropriate assumptions about the science and geology. He believes the conclusions in the paper are wrong and says his views are backed up by rebuttals from the Lawrence Berkeley National Laboratory, the Pacific Northwest National laboratory and the American Petroleum Institute.
The British Geological Survey confirmed it was looking at the Economides findings and was hoping to shortly produce a peer-reviewed analysis.
UPDATE: You can read the critique from Pacific Northwest National Laboratory here. I hope they publish it. The fact is that the concerns laid out in the new study are not new ones. Indeed, my 2008 post quoted a BusinessWeek piece, “The Dirty Truth About Clean Coal“:
The method is widely viewed as being decades away from commercial viability. Even then, the cost could be prohibitive: by a conservative estimate, several trillion dollars to switch to clean coal in the U.S. alone.Then there are the safety questions. One large, coal-fired plant generates the equivalent of 3 billion barrels of CO2 over a 60-year lifetime. That would require a space the size of a major oil field to contain. The pressure could cause leaks or earthquakes, says Curt M. White, who ran the U.S. Energy Dept.’s carbon sequestration group until 2005 and served as an adviser until earlier this year. “Red flags should be going up everywhere when you talk about this amount of liquid being put underground.”
Since CCS is probably at least two decades away from being practical and affordable for large-scale commercialization (assuming we have a high and rising CO2 price by then), we’ll have plenty of time to test different wells and geologies and find out just how many of those red flags we should be paying attention to.
Fortunately, there are many, many other carbon-reducing and clean energy solutions available to us now: