Book Review: Carbon Capture, Howard Herzog

A review of Howard J. Herzog, Carbon Capture (Cambridge: MIT Press, 2018), 198 pp.

Some solutions to climate change roam the earth looking for someone to champion them. Carbon Capture and Storage (CCS) has few friends. Liberals think it is a figleaf over continued use of fossil fuels. CCS, they say, allows business as usual under the vague technological promise that CCS will someday remove what we are carelessly putting into the atmosphere now. On the other hand, conservatives seem to regard CCS as another expensive regulatory burden on the already high costs of producing energy on a large scale. CCS, as Herzog says, “has become an orphan technology” (p. 151).
In fact, CCS needs looking into by all of us, because it will likely be a part of our future struggles to reach the 2 or 1-1/2 degree Centigrade goal advanced by the Paris agreement of late 2018. Howard J. Herzog, an engineer at MIT, has been studying carbon capture and storage for much of his professional life, and he has offered us a small and clearly written overview of the field called, simply, Carbon Capture.
This useful little book describes the scientific processes for removing CO2 from industrial plants along with safe methods of storage afterward, and provides updates on existing or recently closed projects to remove and store CO2 at specific locations. A reader could hardly ask for more from so compact a book.
Carbon Capture begins with a reminder, much needed, of where we are. We used to worry about unsustainability because of the depletion and exhaustion of sources of fuel (“the end of oil,” for example). Our problem now, of course, is precisely the opposite: to put it simply, “we are awash in fossil fuels” (p. 35). It is very unlikely that all of the existing vast and valuable carbon-intensive assets will be left entirely stranded underground. Enter carbon capture: these technologies will likely be used while we are still burning some of the assets to keep the lights on before a carbon-free economy arrives to save the day.
Where possible, Herzog gives us reliable rules of thumb and simple, dependable summary judgments. For example, he says that the rough ratio of carbon intensity of coal, oil, and gas is 5, 4, 3. That makes it easy to see why natural gas has become an essential bridge to a different future for energy production. Depending on the process of combustion and conversion to energy, natural gas at times emits only half the carbon that coal does (p. 25).
After this brilliant introduction, the book, of necessity, descends a bit into the techniques and science of carbon capture—complete with a Rube Goldberg-like diagram of the “amine process” on page 44. The engineering is too complicated to explain here but suffice it to say that there are both pre- and post- combustion (smokestack) methods for CO2 removal.
Whenever the subject of CCS arises at a CCL meeting, someone will be quick to raise the problem of leakage from storage. The chapter on that subject should be reassuring. Scientists know a great deal about geology because of the economic importance of drilling and mining, and sealing the CO2 underground seems to be the least of the difficulties.
Carbon Capture also includes a lengthy and reasonable discussion of possible methods or removing CO2 from the atmosphere after it is already in the air. These methods are uncertain, very expensive, and, so far, not scalable. “The hard engineering reality,” Herzog explains, is that the “best way to remove CO2 from the air is to not release it into the air in the first place” (p. 133).
I finished reading this book an optimist, in part because of the carbon capture technologies described in it, but mostly I regained my accustomed confidence in the levelheaded intelligence and competence of scientists and engineers.
Mark E. Neely, Jr., member of the State College Chapter of the Citizens’ Climate Lobby

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