Engineered CO2 Disposal on Land and Oceans

In equation (3), these options promote CO2 uptake through FDisp.

Carbon Separation with Ocean Storage by Deep Ocean Injection

The addition of pure liquid CO2 in the deep ocean has potential for being a low-impact and highly effective mitigation option (Brewer, Chapter 27, this volume). There is still, however, little understanding of the potential effects of the instability of CO2

deposits in the deep ocean and of the negative effects of the formation of CO2-clathrates and a substantial lowering of pH on deep ocean biota. If numerous sequestration sites were concentrated in specific, rare deep ocean habitats, this practice could endanger biodiversity at these locations, but it seems likely the effects would be local. Further away a moderate pH decrease might be of similar magnitude as that expected from rising atmospheric CO2 levels. In light of how little is known, deep ocean disposal may have unexpected effects on marine chemistry and ecosystems. Public opinion is skeptical about the technique. The London Convention (the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972) is often cited as a treaty that could prohibit such a strategy.

Carbon Separation with Geological Storage in Sediments and Rocks

Given adequate technologies to capture CO2, largely from industrial processes, CO2 can be disposed of in exhausted oil and gas wells and in saline aquifers. This method is a relatively clean solution provided there are not CO2 escapes, dissolution of host rock, sterilization of mineral resources, and unforeseen effects on groundwater (Metz et al. 2001, Section 3.8.4.4). At this stage, there are still large uncertainties regarding these possible environmental impacts, but it remains a promising option.

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