Dual fluidized bed gasification (DFBG) technology requires a combination of two fluidized beds. Fluidized bed (FB), on the other hand, has different types depending on, for example, the gas velocity inside the bed. The present article intends to clarify what types of FBs should be chosen for the FB combination of the DFBG in terms of improving gasification efficiency and enhancing tar-destruction capability. Gasification tests in a 5.0 kg/h pilot gasification plant demonstrated that under the same conditions the combination of a dense low-velocity FB (LVFB) fuel gasifier and a high-velocity pneumatic riser (HVPR) char combustor allowed higher gasification efficiency and lower tar production than the combination of an HVPR fuel gasifier and an LVFB char combustor did. Consequently, the article concludes that the superior technique choice for the DFBG is to deploy its fuel gasification into an LVFB and its char combustion into an HVPR. An HVPR char combustor is necessary because it maintains the steady circ...