NOVELTY - The method comprises: providing first and second container spaces at a biogas plant; adding an activator to provide a biomass for a biochemical treatment; adding (34) the biomass into the first and second container spaces; creating (36) a first reaction condition for the formation of acetic acid, at a temperature of 49-51 degrees C, from the added biomass in the container spaces; and adjusting a pH value of the acetic acid to 3-3.5. An acetic acid formation activator is added to create the first condition in the container spaces, and includes a germinated seed material (10-50 wt.%) and an enzyme.    USE - The method is useful for producing biogas from biomass (claimed).    ADVANTAGE - The method allows simple, efficient and economical production of the biogas from the biomass with less effort.    DETAILED DESCRIPTION - The method comprises: providing first and second container spaces at a biogas plant; adding an activator to provide a biomass for a biochemical treatment; adding (34) the biomass into the first and second container spaces; creating (36) a first reaction condition for the formation of acetic acid, at a temperature of 49-51 degrees C, from the added biomass in the container spaces; and adjusting a pH value of the acetic acid to 3-3.5. An acetic acid formation activator is added to create the first condition in the container spaces, and includes a germinated seed material (10-50 wt.%), an enzyme, living yeast and living acetic acid bacteria that are configured to activate the formation of acetic acid. The method further comprises: transferring the biomass and the formed acetic acid from the first container space into the second container space; creating a second reaction condition for the formation of methane in the second container space; measuring the pH value of the biomass in the second container space; transferring other biomass and the other formed acetic acid from the first container space into the second container space in dependence of the measured pH value in the second container space; providing a third spatially separated container space from the first and second container spaces to the biogas plant; transferring the biomass from the second container space into the third container space; creating a third reaction condition for the formation of other methane in the third container space; measuring the pH value of the biomass in third container space; and transferring the other biomass from the second container space into the third container space in dependence of the measured pH value in the third container space.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a method for producing biogas from biomass.    Adding the biomass into the first and second container spaces (34)    Creating a first reaction condition for the formation of acetic acid (36)    Transferring the biomass from the second container space into the third container space (90)    Creating a third reaction condition for the formation of other methane in the third container space (100)    Measuring the pH value of the biomass in third container space. (110)