A method and apparatus for producing activated carbon from biomass or other solid carbonaceous feed within a housing containing boiler components, by spatial separation of drying, pyrolysis and activation zones as the feed is conveyed across the bottom of the housing, such that the thermal requirements for drying, pyrolysis, and activation of the solid carbonaceous feed occur by direct radiation from the combustion flame located above the drying, pyrolysis and activation zones. The balance of the heat not required for drying, pyrolysis, and activation is used to vaporize and superheat steam as part of a conventional steam/electric power plant.