Abstract: An apparatus for the combustion of organic waste such as poultry litter/manure, cow manure and swine manure, and/or human waste, and/or biomass using a moving grate over a stationary perforated plate to convert organic waste into usable energy. The unprocessed fuel is fed into the combustion chamber through a feed hopper by a moving grate being continuously pulled over a stationary perforated plate. The raw fuel is metered using a guillotine gate apparatus to control the depth of the fuel bed on the moving grate. Temperature controlled combustion air is directed under the stationary perforated plate (under fire air) into discreet controllable under fire air zones to initiate and drive the combustion process. The stationary plate is sectioned to match the discreet under fire air zones with holes and/or slots (perforations) shaped and sized for proper under fire air distribution and pressure drop through the plate.