I have just had a piece published in the Bulletin of the Atomic Scientists: ‘We’d have to finish one new facility every working day for the next 70 years’—Why carbon capture is no panacea . I’m not allowed to repost the whole article here, but it is open access on the Bulletin website.
I looked again at the outsized role that carbon capture and storage (CCS) along with Bioenergy Carbon Capture and Storage (BECCS) play in most of the IPCC 2 degree models. I have argued previously that the gigantic quantities of CO2 that need to be sequestered in geological reservoirs, according to these models, face huge obstacles in terms of scalability, financing, technical hurdles and public acceptance.
A recent paper in Science reported on a breakthrough experiment in Iceland in which CO2 (from a volcanic source) dissolved in water was injected into basalts at depths of 400-1000 metres. Using isotopic and chemical tracers, the researchers estimate that the CO2 had been mineralized into benign and stable carbonate minerals in the space of just two years. This was faster than suspected and, if this process turns out to be scalable, then sequestration in basalts would provide a solution to the need to monitor conventional sedimentary rock disposal sites for leakage over the long term.
Unsurprisingly, the “if” in “if this process turns out to be scalable” is a big one. For one thing, the Icelandic process requires a lot of water. I estimated, just as an example, that if the current emissions from the US were sequestered in the Columbia River Basalt Group, it would require half of the annual flow of the mighty Columbia River itself. Of course, nobody is proposing sequestration on such a scale in one region, it’s just an illustration of the scale of water required form the river and the scale of fluid injection required into the basalts.
Anyway, please read the article, if you are interested.
Below, I have included some footnotes and references that I had included with my original draft, but that were not included in the final Bulletin version. Note that subsequent edits have change the order and some of the wording.
Excerpts from my first draft, with footnotes.
- For example, according to the International Energy Agency: “Carbon capture and storage (CCS) is the only technology able to deliver significant emissions reductions from the use of fossil fuels.”
- And Oxford University climate scientist Myles Allen claims: “A global ban on fossil fuels is neither affordable nor enforceable, so capture and disposal of CO2 is the only option. Assuming we don’t want to turn the world over to cultivating biofuels and resort to eating insects, then there will always be some uses of fossil fuels for which there is no effective non-fossil substitute, much as environmentalists hate to admit it. “
- Conversely, climate expert Joe Romm, writing at Climate Progress, has written that: “CCS simply hasn’t yet proven to be practical, affordable, scalable, and ready to be ramped up rapidly.”
- While Energy historian Vaclav Smil comments: “…in order to sequester just a fifth of current CO2 emissions we would have to create an entirely new worldwide absorption-gathering compression-transportation- storage industry whose annual throughput would have to be about 70 percent larger than the annual volume now handled by the global crude oil industry whose immense infrastructure of wells, pipelines, compressor stations and storages took generations to build.”
- Recently, the results of a research project in Iceland went against this trend and put CCS briefly back into the news.
- In cases where atmospheric concentrations of carbon dioxide are limited to 450 parts per million, mitigation costs increase by 138%, compared to the baseline scenarios in which no CCS is deployed.
- The Paris Agreement, signed by all of the world’s governments in December 2015, calls for the Parties “to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century”.
- Indeed, of the 400 of the IPCC scenarios that keep warming below the Paris agreement target, some 344 involve deployment of negative emissions technologies. The remaining 56 models all assume that emissions reduction started in 2010.
- As an example, a prominent published model that limits warming to 2°C envisages primary energy use in the year 2100 to be (in approximate numbers): 25% renewables and nuclear energy; 15% fossil fuels without CCS, mostly natural gas and; 60% fossil fuels and bioenergy with CCS. In this model, 30 billion tonnes of CO2 from fossil fuels will be sequestered annually in 2090 in addition to 10 billion tonnes of CO2 from biofuels.
- The annual mass of 40 billion tonnes of CO2 mentioned earlier would have a volume of about 65 billion cubic metres, for comparison, this is about three times the average annual discharge of the Hudson River.
- Basalts are natural CO2 sequestration sites. Exposed basalts, especially in the tropics, are estimated to absorb about 180 million tonnes of CO2 every year.
- Basalts on the sea floor react with dissolved CO2 in the seawater to take up about 150 million tonnes annually.
- These processes, along with other weathering activity, are important on geological timescales for absorbing CO2 emissions from volcanoes (estimated at around 500 million tonnes per year).
- A recent article in Science by geologist Joerg Matter of Southampton University and colleagues reported on an experiment in Iceland in which volcanically-sourced CO2 was dissolved in water and injected into basalts at depths between 400 and 800 metres.
- One of the best onshore candidate areas for basalt sequestration in the USA is the Columbia River Plateau located in eastern Washington, NE Oregon and western Idaho.
- As an illustration of how much water might be required, if attempts were made to sequester all US CO2 emissions from fossil fuels (5.2 billion tonnes in 2014), some 130 billion tonnes of water would be used, approximately half of the annual flow of the Columbia River (240 billion tonnes).
- The most extensive area of basaltic rock on the planet is the ocean floor. One part of the ocean that has been identified as potential location for sequestration of CO2 in basalts is the Juan de Fuca plate in the Pacific Ocean west of Washington, Oregon and Northern California.
- There is little public demand for CCS or for government funding it, particularly in western Europe, as Joerg Matter, quoted in the Guardian, said: “In Europe you can forget about onshore CCS.”
- To stabilize rising global temperatures requires not just greatly reducing emissions, but getting them to zero.
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 Matter, J. M., Stute, M., Snæbjörnsdottir, S. Ó., Oelkers, E. H., Gislason, S. R., Aradottir, E. S., … & Axelsson, G. (2016). Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions. Science, 352(6291), 1312-1314.
 Zakharova, N. V., Goldberg, D. S., Sullivan, E. C., Herron, M. M., & Grau, J. A. (2012). Petrophysical and geochemical properties of Columbia River flood basalt: Implications for carbon sequestration. Geochemistry, Geophysics, Geosystems, 13(11).
 Goldberg, D. S., Takahashi, T., & Slagle, A. L. (2008). Carbon dioxide sequestration in deep-sea basalt. Proceedings of the National Academy of Sciences, 105(29), 9920-9925.
 Matthews, H. D., & Solomon, S. (2013). Irreversible does not mean unavoidable. Science, 340(6131), 438-439.
Open-access versions of some of the papers cited above can be found by copying the paper title and doing a search by pasting it into the search box in Google Scholar.