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Southern Company is moving forward with its testing program. Tom Johnson describes their experience with both switchgrass and small wood chips. Switchgrass comes in bales and goes through a tub grinder before it is pneumatically conveyed to dedicated burners which are above the coal burners. Co-firing ranges from 5 to 10 percent at the Gadsen. However it is not continuous. Small wood chips (less than ½ inch) can be fed through the coal pulverizers. Larger chips would cause problems. There is not likely to be a problem with the quality of the ash but a new ASTM specification would be needed. The one problem other than supply would be concern about effect on the SCR catalyst. European experience shows only a slightly reduced catalyst life. But Southern would like to directly evaluate performance. |
