NOVELTY - The method comprises gasifying a biomass-rich material in a gasifier (7) containing a fluidized bed (7b) at a temperature of less than or equal to 700 degrees and a pressure of less than or equal to 1.5 atm to produce a crude synthesis gas, quenching the crude synthesis gas product, scrubbing the quenched synthesis gas effected at a gas entry temperature of 150-350 degrees , an exit temperature of 30-90 degrees and at a pH of 4-7 under alkaline conditions, and subjecting the scrubbed synthesis gas to a adsorption step to provide a clean synthesis gas and to pass the synthesis gas through an adsorption column (29) packed with a material.    USE - The method is useful for producing synthesis gas or syngas from biomass and for cleaning or conditioning the crude synthesis gas, which is used as a fuel gas in gas and steam boiler plants and to produce other materials such as methanol.    ADVANTAGE - The method is capable of efficiently, easily and economically producing synthesis gas or syngas from biomass and cleaning or conditioning the crude synthesis gas.    DETAILED DESCRIPTION - The method comprises gasifying a biomass-rich material in a gasifier (7) containing a fluidized bed (7b) at a temperature of less than or equal to 700 degrees and a pressure of less than or equal to 1.5 atm to produce a crude synthesis gas, quenching the crude synthesis gas product, scrubbing the quenched synthesis gas effected at a gas entry temperature of 150-350 degrees , an exit temperature of 30-90 degrees and at a pH of 4-7 under alkaline conditions, and subjecting the scrubbed synthesis gas to a adsorption step to provide a clean synthesis gas and to pass the synthesis gas through an adsorption column (29) packed with a material having a porosity of greater than or equal to 40%, a reactive adsorption bed and a zinc oxide filtration bed, and subjecting the synthesis gas subsequent to the catalytic reforming. The step of quenching the crude synthesis gas comprises contacting the crude synthesis gas with alkaline water, which is subjected to steam reforming effected in the presence of a catalyst at a temperature of 750-800 degrees .    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a biomass material, which is gasified to produce a crude synthesis gas.    Gasifier (7)    Fluidized bed section (7b)    Valves (9a,9b)    Recovery unit (20)    Adsorption column. (29)