NOVELTY - The method for operating a biogas plant having a fermentation tank (36), which is led for maintaining a continuous fermentation process of moving fresh substrate such as slurry, comprises making a first quantity (12) by mixing liquid substrate, portioning the first quantity of the fresh substrate in several storage containers (16, 18, 20, 22), intermixing the fresh substrate in a first storage container while no measurements for intermixing are carried out in a second storage container, and removing the fresh substrate from the first storage container.    USE - Method for operating a biogas plant to produce methane.    ADVANTAGE - The method is capable of effectively and rapidly operating the biogas plant with high efficiency thus producing the methane with high yield.    DETAILED DESCRIPTION - The method for operating a biogas plant having a fermentation tank (36), which is led for maintaining a continuous fermentation process of moving fresh substrate such as slurry, comprises making a first quantity (12) by mixing liquid substrate, portioning the first quantity of the fresh substrate in several storage containers (16, 18, 20, 22), intermixing the fresh substrate in a first storage container while no measurements for intermixing are carried out in a second storage container, removing the fresh substrate from the first storage container, and supplying the removed fresh substrate into the fermentation tank of the biogas plant. The substrate is led past into the fermentation tank on a solid bed, on which the microorganisms responsible for the fermentation process adhere. The making of the first quantity takes place by delivering the fresh substrate to a location of the biogas plant in an intermixed state and by intermixing the substrate in a container (10) at the location of the biogas plant, in which the first quantity of the fresh substrate is contained. The storage container is transported with a forklift, is not engaged into the ground, and is an intermediate-bulk-container. The intermixing of the fresh substrate is carried out by circulating the substrate with a pump. The conveying speed of the pump is controlled in dependent of filling level in the first storage container. The substrate is fed back into the first storage container from the bottom during circulation. In the intermixing of the fresh substrate, a stream of substrate fed back into the first storage container is directed against a baffle plate. The intermixing, removing and supplying steps are repeated in the first storage container corresponding to the second container when falling below a predetermined filling level. An INDEPENDENT CLAIM is included for a biogas plant.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of a method for operating a biogas plant.    Container (10)    First quantity (12)    Storage containers (16, 18, 20, 22)    Stirrer (24)    Fermentation tank. (36)