Reducing CO2 emissions from coal burning is an important priority, says Morris Argyle in the Department of Chemical and Petroleum Engineering at the University of Wyoming. He also suspects that removing CO2 from flue gases may be easier than previously thought.Argyle says CO2 can be absorbed by fly ash, the residue left over after coal burning. In tests where carbon dioxide was bubbled through a fluidised bed of fly ash for 15 minutes, the ash absorbed up to 4% of the gas passing through.
His suggestion is that CO2 could be regularly sequestered from flue gases by passing exhaust fumes through such a fluidised bed of fly ash. The resulting waste could then be buried.
It looks like a very simple way to reduce emissions, especially since the ash has to be disposed of anyway. But how stable is the carbon dioxide once it is absorbed by fly ash? It would be no good burying the ash only to find the carbon dioxide leaking out over the next few years.
See the full CO2 capturing patent application
Justin Mullins, New Scientist contributor
