will tend to stay at the surface. Assume that the CO2 from a 1 GW(e) power plant is captured and injected into a well. If 0.1 percent escapes during the injection, there would be a point source of 6.9 mol s–1 of CO2. At a point 1 km downstream, with a wind speed of 5 m s–1 and a plume width of 100 m and plume height of 100 m, the CO2 enhancement would be 3.3 ppm, causing a 14C depletion of 0.89 percent. A second scenario is escape from the geological formation into which the CO2 has been stored. If 0.2 percent of the sequestered CO2 escapes per year (residence time 500 years), the leak would increase over time as more CO2 is pumped into the formation. After 1 year the leak rate would be 14 mol s–1, after 2 years 28 mol s–1, and so on. In addition, when the escaping CO2 goes through soil, the CO2 mole fraction in soil air would become very high, eventually depriving the vegetation of sufficient oxygen in the root zone and leading to plant death, which should be easily detectable.

REFERENCES

Dhakal, S., S. Kaneko, and H. Imura, 2003, CO2 emissions from energy use in East-Asian mega-cities, in Proceedings of the International Workshop on Policy Integration Towards Sustainable Urban Use for Cities in Asia, February 4-5, East-West Center, Honolulu, Hawaii, available at <http://enviroscope.iges.or.jp/ contents/6/index.html>.

IPCC (Intergovernmental Panel on Climate Change), 2005, Carbon Dioxide Capture and Storage, IPCC Special Report, prepared by Working Group III of the Intergovernmental Panel on Climate Change, B. Metz, O. Davidson, H.C. de Coninck, M. Loos, and L.A. Meyer, eds., Cambridge University Press, New York, 442 pp.



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