Sequestration : the underground storage of carbon dioxide

Underground storage of industrial quantities of carbon dioxide in porous and permeable reservoir rocks has been taking place for the last 11 years at the Sleipner West gas field in the North Sea. A further commercial-scale CO2 storage project has recently begun at In Salah, Algeria, and the Snohvit field, Barents Sea, is to begin injecting CO2 underground in late 2007 or early 2008. A monitored CO2-EOR project is underway at Weyburn, Canada and research scale injection projects have been undertaken at Nagaoka (Japan), Frio (USA) and K12-B (offshore Netherlands). This demonstrates that CO2 can be successfully injected into underground storage reservoirs on a large scale. Natural analogues (natural fields of CO2 and other buoyant fluids) demonstrate that under favourable conditions gases can be retained in the subsurface for millions of years. Although there is still very significant uncertainty in the actual figures, it appears that globally there is enough underground storage capacity for CO2 storage technology to make a significant impact on global emissions to the atmosphere. Some other major issues that must be addressed if this technology is to spread to power stations, and thus make a significant impact on global CO2 emissions, are the cost of CO2 capture, further demonstrations of safe and secure storage and public acceptance that long-term storage will be successful.