The invention provides an apparatus which consists of two fluidized beds 1 and 2 separated by a vertical divides' 5. A positive displacement device such as an auger 3 moves the bed material from the reduction side to the combustion side of the device below the fluidization zone. The height of the two fluidized beds is equalized by movement of the bed material through a hole 4 In the vertical divider, from the high temperature side 1 (zone 1) to the tow temperature side 2 (zone 2). The bed material that moves through the hole 4 provides energy to drive reactions that may occur on the reduction side. Energy may also be provided to zone 2 by means of conductive and radiative heat transfer through the dividing wall 5. Energy is provided to zone 1 by means of an exothermic reaction, typically combustion of a fuel 13 using air 12.