The 26th International Conference on Offshore Mechanics and Arctic Engineering · 2007

Ocean storage of carbon dioxide: pipelines, risers and seabed containment

Andrew Palmer, David Keith, and Richard Doctor

Eight hundred tonnes of carbon dioxide (CO₂) are dumped into the atmosphere every second. There has been a progressive rise in the CO₂ content of the atmosphere, from 270 ppm in the pre-industrial era to more than 380 ppm now, rising by 15 ppm/decade. The overwhelming scientific consensus is that this is having a large effect on climate, and that as a result the Earth’s temperature will rise by about 2°C by 2100. Agriculture, forestry, fisheries, the biosphere and human health will all be affected. The level of the sea will rise by between 0.5 and 1 m, and there is a possibility of a much greater and catastrophic rise if warming should lead to a collapse of the Greenland or Antarctic ice sheets. Adaptation to the changes and mitigation of the consequences will play a part in human response. Reducing the use of fossil fuels through energy conservation can also contribute, but the scale of the problem is so huge, and fossil fuel use is so extensive, that conservation alone will not eliminate the problem, particularly as fossil fuel use is rapidly increasing in many developing countries, above all in China and India. It is estimated that current emissions of 7 GtC/y (gigatonnes of carbon per year) will rise to 14 GtC/y by 2050 under a business-as-usual scenario, and that climate change will accelerate, as may indeed be happening already. Another option to deal with CO₂ is carbon capture and storage (CCS), which has been the subject of a recent IPCC (Intergovernmental Panel on Climate Change) report. CO₂ is most easily captured at large sources, such as power stations, cement plants, and steelworks. The technology to extract CO₂ from combustion products exists, but is expensive. Capture from small sources such as cars, buses, domestic heating furnaces, and cooking fires is likely to be very expensive indeed, and has scarcely been considered.

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