NOVELTY - The device for producing biogas by microbial conversion of pumpable biomass, comprises a fermenter (1) for receiving the biomass, where the fermenter includes a device for mixing the biomass contained in the fermenter and an unit (9) for tempering the biomass. The mixing device has a stirrer (3). The tempering unit is arranged in a flow path of the biomass produced by the stirrer, so that a part of the biomass flows through and flows around the tempering unit. The tempering unit is formed as a heating register and comprises a tube flowed by a tempering medium.    USE - Device for producing biogas by microbial conversion of pumpable biomass.    ADVANTAGE - The device can be economically constructed with high efficiency, and ensures effective and simple production of the biogas with improved heat transfer effect.    DETAILED DESCRIPTION - The device for producing biogas by microbial conversion of pumpable biomass, comprises a fermenter (1) for receiving the biomass, where the fermenter includes a device for mixing the biomass contained in the fermenter and an unit (9) for tempering the biomass. The mixing device has a stirrer (3). The tempering unit is arranged in a flow path of the biomass produced by the stirrer, so that a part of the biomass flows through and flows around the tempering unit. The tempering unit is formed as a heating register and comprises a tube flowed by a tempering medium, where the tube is flowed around by the biomass. The tempering unit has tubes lying next to each other and transverse to a flow direction (7) of the biomass, where the two tubes branch off from a tempering medium inlet and flow into a common tempering medium outlet. Several heating registers are arranged one behind the other in the flow path of the biomass in the flow direction. The distance between the stirrer and the tempering unit is 10 cm to 3 m. The stirrer is a slow-running axially conveying stirrer with 2-4 stirrer blades. INDEPENDENT CLAIMS are included for:    (1) a method for producing biogas; and    (2) a heating- and stirring register for tempering biomass in a fermenter.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of a fermenter.    Fermenter (1)    Stirrer (3)    Drive (5)    Flow direction (7)    Tempering unit. (9)