NOVELTY - Producing liquid biofuel from biomass (100), comprises: gasifying biomass at elevated temperature to get raw synthesis gas (200); and post processing at least part of raw synthesis gas to the biofuel, where post processing comprises removing at least part of sulfur from synthesis gas (360) to get treated synthesis gas (470), and allowing at least part of treated synthesis gas to react with steam (water) in presence of catalyst, thus modifying molar ratio of hydrogen to carbon monoxide to get shifted synthesis gas (478) with adjusted molar ratio of hydrogen to carbon monoxide.    USE - The method is useful for producing liquid biofuel from biomass.    ADVANTAGE - The method is simple, cost-effective and utilizes a smaller catalyst bed. The method is not sensitive to the sulfur content of the biomass feedstock, which allows for more flexibility for the feedstock, and the purchasing price of raw material to be reduced with more flexibility. The flexibility of the feedstock content optimizes based e.g. on the price of the biomass, where price of e.g. stumps, wood residues, and bark depend on their availability. The sulfur removal unit is located before the gas shifter, the gas shifter bypass configuration is arranged to adjust the molar ratio of water to carbondioxide of treated synthesis gas, thus eliminating maintenance of minimum sulfur level. Sulfur dosing system, to maintain an acceptable sulfur level in the gas shifter, when using biomass with low sulfur level, is not needed in method. The treated synthesis gas allows for standard operation of high temperature shift (HTS) and low temperature shift catalysts. Permanent adaption of the gas shift temperature to compensate for activity changes is therefore not required, thus HTS catalyst can be operated at constant conditions. The method increases the life time of the HTS catalyst by avoiding sulfidation/desulfidation cycles, which would occur if the catalyst would be located in the raw gas section and if the biomass feed stock alternates between high and low sulfur biomass. The gas shifter is located downstream of the scrubber, the compressor and the sulfur removal unit. All these units remove some impurities from the synthesis gas. Thus, the risk of poisoning of the gas shift catalyst by unforeseen impurities is relatively low, compared to a system where the gas shifter is located before any of the other mentioned equipment. In addition, for the specified order of the equipment, the risk of dust deposition or tar or volatile alkali condensing in the gas shifter is reduced, compared to a system where the gas shifter is located before any of the other mentioned equipment. The catalysts used in the gas shifter are typically sensitive to oxygen. The catalyst may react with oxygen such that their activity ceases. Oxygen, on the other hand, is injected to the process in the reformer. Thus method has sufficient safety measures to prevent larger quantities of oxygen from getting in contact with the shift catalyst, it can generally be the that the further away the gas shifter is from the oxygen injection points, the smaller the risk for oxidizing the catalysts in the gas shifter.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a system for producing liquid biofuel from biomass, comprising: a gasification reactor for gasifying biomass at an elevated temperature to produce raw synthesis gas; a post processing system arranged to produce the liquid biofuel from the raw synthesis gas, where the post processing system comprises a sulfur removal unit, gas shifter, and means for conveying at least part of treated synthesis gas from the sulfur removal unit to the gas shifter.    DESCRIPTION OF DRAWING(S) - The figure shows compression, sulfur removal, synthesis gas shifting, carbon dioxide removal, and subsequent process steps in a process for producing liquid biofuel from solid biomass, where a physical wash is used.    Liquid biofuel from biomass (100)    Raw synthesis gas (200)    Synthesis gas (360)    Treated synthesis gas (470)    Shifted synthesis gas (478)