However, matlab negative aspects of this kind of gasifier are related to difficulties in coping with biomass with both high moisture and ash contents, together with fairly low universal thermal efficiency. Multistage constant bed gasifiers are becoming engineering reference seeing that matlab 2000s because of their skill for producing engineering syngas with very low tar content material. The concept of staged fixed bed gasifiers is dependent upon matlab decoupling of biomass pyrolysis, fuel gases combustion, and char gasification, by using two separated reactor vessels. This separation allows for engineering greater management engineering matlab pyrolysis and gasification ranges, affording matlab possibility of independently optimizing each level. This system optimization effects in matlab production of engineering syngas containing just about zero tars, which are removed by combustion in matlab high temperature gasification vessel. Low tar contents 10 50 mg/Nm3 were suggested with staged gasification strategies operated for long periods by TK Energi A/S TKE, matlab Technical University of Denmark DTU, and CIRAD France.