NOVELTY - Plant for producing biogas, comprises at least one fermenter (1) for fermenting solid biomass (13), comprising a device to pressurize biomass with a liquid medium, a gas outlet (2) to remove biogas from fermenter, and a gas inlet (3) to supply gases to the fermenter. The gas inlet is connected with a biogas source, preferably with gas outlet, a biogas line (4) and/or with a biogas reservoir. The gas inlet is formed such that the liquid medium is removed through gas inlet after passing through biomass, and biogas is introduced into fermenter during supplying of the liquid medium into fermenter.    USE - The plant is useful for producing biogas.    ADVANTAGE - The plant prevents the loss of gas by rinsing, and accommodates higher content of dry substrate.    DETAILED DESCRIPTION - Plant for producing biogas, comprises at least one fermenter (1) for fermenting solid biomass (13), comprising a device to pressurize the biomass with a liquid medium, a gas outlet (2) to remove the biogas from the fermenter, and a gas inlet (3) to supply gases to the fermenter. The gas inlet is connected with a biogas source, preferably with the gas outlet, a biogas line (4) and/or with a biogas reservoir. The gas inlet is formed such that the liquid medium is removed through gas inlet after passing through the biomass, and the biogas is introduced into the fermenter during supplying of the liquid medium into the fermenter. An INDEPENDENT CLAIM is also included for operating the plant for producing the biogas, comprising introducing the biomass into the fermenter loaded with the liquid medium, and anaerobically fermenting for producing the biogas. The biogas is passed into the fermenter during supplying the liquid medium through the gas inlets such that drainage channels are formed for the liquid medium, where the liquid medium is removed over the gas inlets after passing through the biomass.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the plant for producing the biogas.    Fermenter (1)    Gas outlet (2)    Gas inlet (3)    Biogas line (4)    Biomass (13)