Why Carbon Sequestration Won’t Work

  • Date: 09/08/10

For those who believe in anthropogenic global warming, carbon dioxide is public enemy number one. They warn that CO2 must be avoided at all costs or Earth will heat up uncontrollably causing all sorts of ecological havoc. One proposal for avoiding global warming is the sequestration of CO2 by trapping it at combustion sites or extracting it directly from the air. Supposedly, such sequestration could help avoid a large rise in atmospheric CO2 from the use of fossil fuels, avoiding the hellish fate that surely awaits mankind otherwise. Referred to as carbon capture and storage (CCS), the coal industry has seized on sequestration as a way to get greens off their backs and stay in business. However, it is not clear how effective different types of sequestration and associated leakage are in the long term, or what their consequences might be. A recent paper takes a critical look at the sequestration option.

In an article in the June 27, 2010, issue of Nature Geoscience, “Long-term effectiveness and consequences of carbon dioxide sequestration,” Gary Shaffer, from the Department of Geophysics at the University of Concepcion in Chile, has provided a sobering look at carbon sequestration in its various guises. His analysis presents the results from projections over 100,000 years for five scenarios of carbon sequestration and leakage using an Earth system model.

The primary goal was to keep global warming, at least as predicted by the computer model, to under 2°C. The two basic sequestration options examined were pumping CO2 into the deep ocean and injecting it into underground geological formations.

The study found that deep-ocean carbon storage leads to extreme acidification and CO2 concentrations in the deep ocean, together with a return to the adverse conditions of a business-as-usual projection with no sequestration over several thousand years. In other words, it won’t work in the long run and it will mess up the oceans.

Geological storage sites for CO2 vary greatly in type and location, with deep saline formations providing by far the largest potential storage capacity. Again, unsurprisingly, the model simulations found that all three of the leaky geological storage scenarios didn’t eliminate global warming, they just postponed it. The only way to make CCS work is to assume zero leakage essentially forever. Some dismiss possible leakage, suggesting that we simply continue to extract CO2 from the atmosphere and re-inject it. This would essentially commit humanity to a +10,000 year world wide project of continuous extraction and sequestration. Bottom line, CO2 storage would have to last for tens of thousands of years to be successful.

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