Efficient control of heat transfer to and from biomass in every step of the process treatments becomes crucially important. In particular, depending upon the desired heat transfer characteristics of biomass conversion technol­ogy, a wide variety of process designs and reactor configurations have been proposed and demonstrated. Some of the examples in the reactor design include bubbling fluidized bed, circulating fluidized bed, entrained flow, ablative tube, rotating cone, vacuum, twin-screw, and others. Examples of a heat transfer medium utilized in such processes include hot sand which is usually recirculated in the process system as a direct-contact heat transfer medium as well as a means for thermal energy preservation.