Sunday, June 26, 2016

In a first, Iceland power plant turns carbon emissions to stone

In a first, Iceland power plant turns carbon emissions to stone, 9 June 2016, no author given

This is a report of ground-breaking – literally! – research recently published in the journal Science, claiming that pressurized CO2 pumped into basalt formations underground is rapidly absorbed, transforming the basalt into carbonate minerals that permanently lock the carbon into place.  If true, this finding would substantially change the picture regarding “carbon capture and sequestration” (CCS), the storage of carbon dioxide emissions underground to prevent climate change.  CCS is believed by many (such as the IPCC, in their latest report) to be crucial if we are to avoid catastrophic climate change.  This advance would allay fears that CO2 sequestered underground might leak back out into the atmosphere over time, since the CO2 would be tightly locked into permanent mineral structures.  However, this technology requires large amounts of water to be pumped down as well – 25 tons of water per ton CO2, although seawater can be used.  It is also possible that the carbonate minerals might get munched by bacteria that would release methane, perhaps completely reversing the benefits of CCS (or worse).

My take: This has the potential to be revolutionary, but it is important to take these kinds of early scientific results with a big grain of salt; a great deal more research is needed.  Nevertheless, it is big news.  It’s hard to see a path toward sustainability that does not involve CCS, since we rely so heavily on fossil fuels.  It will be difficult to shift off of them completely; even if we manage to reach, say, 80% renewable energy (a very aggressive goal, for technical reasons such as intermittency), the remaining 20% use of fossil fuels would continue to drive atmospheric CO2 ever upward unless we master CCS.  Indeed, the recent Paris Accord negotiations essentially assumed that some form of CCS would be used to offset a large fraction of future emissions.  The problems with this new technology remain large, however.  We presently emit about 40 billion tons of CO2 per year; this technology would thus require burying 1 trillion tons of water, which is 1000 cubic kilometers of water.  Which is a lot of water, although it is only 0.000074% of the total volume of the ocean, if I have done my math right.  The article also mentions the issue of cost, but not prominently enough, I think.  Cost is the big problem that has plagued CCS for decades, because it takes a lot of energy to separate, compress, and inject waste CO2 underground.  It is not clear that the new method improves on that, and so the cost of CCS may remain prohibitive even with this advance – unless, that is, some form of carbon taxation shifts the cost-benefit analysis by increasing the cost to companies of simply releasing waste CO2 into the atmosphere.  But the cost of CCS may be even higher than the “social cost of carbon”, and so even with this technology a carbon tax might have to be set “too high” – higher than the actual damage done by CO2 – before CCS would start to make economic sense.  So, in short: be excited, but remain calm.

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