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Independent Professional: Experienced educator and management consultant for engineering educational institutions, researcher, trainer, technical consultant on sustainable technologies, related to cement manufacturing and characterisation, using industrial and agricultural wastes in cement and concrete, durability of concrete and fuel cell power.

Saturday, March 21, 2009

Conroling Climate Chage: Carbon dioxide capture and storage (CCS)

40 percent of man-made CO2 emissions come from burning coal. One approach that is gaining currency among environmental scientists is carbon dioxide capture and storage (CCS), a form of carbon sequestration in which CO2 is removed from the waste gas of power plants, typically by absorbing it in a liquid, and subsequently burying it deep underground.

Indeed, CCS technology is already in use. Since 1996, the Norwegian company Statoil has been stripping about a million tons of CO2 a year out of natural gas from the Sleipner West field under the North Sea and injecting it at high pressure into a saline aquifer. Avoiding Norway's tax on CO2 emissions balanced most of the costs of the project. An even larger project, begun in 2000, takes CO2 from North Dakota and sinks it into an oil field in Weyburn, Saskatchewan, Canada. Here, selling the extra oil that the injected C02 squeezes out largely offsets the costs. These efforts and others show that the sequestered CO2 can be monitored, and that it largely stays confined underground. These cases notwithstanding, CCS is expensive. Capturing even a modest part of the 25 billion tons of CO2 emitted each year, experts say, will require economic incentives.The technology and technical know already exists. Whether it's adding chemical scrubbers to existing coal plants or building entirely new ones that gasify the coal before burning it (allowing the CO2 to be separated out).

At present, there are two such power plants in the world—one in China that is under construction and a small one in Germany that separates out the CO2 to store it in an abandoned natural gas field. Adding such CCS technology to coal plants adds roughly $ 65 per metric tonne of CO2 to the cost of electricity (2009 estimate), according to Howard Herzog, a research engineer at the Massachusetts Institute of Technology (MIT)

1. Tim Lenton, Nem Vaughan, "The radiative forcing potential of different climate geoengineering options", Atmospheric Chemistry and Physics Discussions, Vol. 9, pp. 2559-2608
2. Stuart E. Strand, Gregory Benford, "Ocean Sequestration of Crop Residue Carbon: Recycling Fossil Fuel Carbon Back to Deep Sediments", Environ. Sci. Technol., 2009, 43 (4), pp 1000–1007

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