NOVELTY - Producing biogas from biomass, comprises (a) supplying the biomass (20) to a digesting device (2), (b) supplying the digested biomass to a part of a first hydrolysis device (6), (c) supplying partially hydrolyzed biomass to a part of a first separating device (8), (d) supplying the solid phase to a part of a second hydrolysis device, (e) supplying partially hydrolyzed biomass in the second hydrolysis device to a part of a second separating device, and (f) supplying the first liquid phase and the second liquid phase separated by the second separating device to a final storage and/or fermenter.    USE - The method is useful for producing biogas from biomass.    ADVANTAGE - The method: produces biogas from biomass, preferably from renewable raw materials with higher yield; and reduces the residence time of the biomass to be fermented in the biogas plant. The biogas plant is compact.    DETAILED DESCRIPTION - Producing biogas from biomass, comprises (a) supplying the biomass (20) to a digesting device (2), where cell disruption takes place and the supplied biomass is at least partially digested, (b) supplying the digested biomass at least to a part of a first hydrolysis device (6), where the digested biomass is at least partially hydrolyzed, (c) supplying at least partially hydrolyzed biomass in the first hydrolysis device at least to a part of a first separating device (8), where a separation takes place in a solid-containing solid phase and in a liquid phase, (d) supplying the solid phase at least to a part of a second hydrolysis device, where the solid phase is at least partially hydrolyzed, (e) supplying partially hydrolyzed biomass in the second hydrolysis device at least to a part of a second separating device, where a second solid phase and a second liquid phase are separated, and (f) supplying the first liquid phase separated by the first separating device, and the second liquid phase separated by the second separating device at least to a part of a final storage and/or fermenter. An INDEPENDENT CLAIM is also included for a biogas plant (1) for producing biogas, preferably for performing the above method, comprising the digesting device that is downstream to a conveying- and/or dosing device, the first hydrolysis device that is downstream to the conveying- and/or dosing device, the digesting device and the first separating device, a solid phase line, which branches from the first separating device and is guided to the second hydrolysis device, a liquid phase line, which branches from the first separating device and is guided to the final storage and/or fermenter, the second separating device downstream to the second hydrolysis device, and a further liquid phase line, which branches from the second separating device and is guided to the final storage and/or fermenter.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of the biogas plant.    Biogas plant (1)    Digesting device (2)    First hydrolysis device (6)    First separating device (8)    Biomass (20)