NOVELTY - The method and device for fermenting fluid plant raw materials as substrate for high efficient production of hydrogen-containing biogas in a combined pack-agitated anaerobic special hydrogen fermenter with a hydrogen-tight double wall, comprise controlling the fermenter over the measuring variables of pH value and temperature and/or over the correcting variables of agitation parameters and loading rate, introducing concentrated plant sap as substrate directly into the fermenter, and obtaining the concentrated plant sap as press sap from fresh plant material or from plant silage.    USE - Method and device for fermenting fluid plant raw materials as substrate for high efficient production of hydrogen-containing biogas in a combined pack-agitated anaerobic special hydrogen fermenter with a hydrogen-tight double wall.    ADVANTAGE - The method and device are capable of economically and efficiently fermenting the fluid plant raw materials with less energy consumption and less effort in an environmental-friendly manner without requiring pretreatment process such as mixing and hydrolysis, provide stable operation of the fermenter even at high loading rates, and allow high biogas yields.    DETAILED DESCRIPTION - The method and device for fermenting fluid plant raw materials as substrate for high efficient production of hydrogen-containing biogas in a combined pack-agitated anaerobic special hydrogen fermenter with a hydrogen-tight double wall, comprise controlling the fermenter over the measuring variables of pH value and temperature and/or over the correcting variables of agitation parameters and loading rate, introducing concentrated plant sap as substrate directly into the fermenter, and obtaining the concentrated plant sap as press sap from fresh plant material or from plant silage. The hydraulic retention time of the substrate in the hydrogen fermenter is under 10 hours. The produced gas mixture consists of hydrogen (up to 70%), carbon dioxide (up to 40%) and less separable water vapor (up to 10%) without further accompanying gas or interfering gas. Microorganisms producing the hydrogen is mixed to culture, which contains Escherichia coli strains and/or Lactobacilli. The process is a wet fermentation process. The fermenter is disposed over a controllable rotating drum insert, which is filled with a fixed bed. The fixed bed consists of filling material of different sizes e.g. high capacity ceramic (zirconium oxide), whose packing density is adapted to the substrate. The substrate supply takes place by a rotational axis (21) of the drum insert, where the rotational axis is implemented as hollow axis. The drum insert consists of perforated cylinders (24) that lie into one another. The hole diameters outwardly decrease from the interior. Several fixed bed chambers are present in the drum insert for the settlement of microorganisms for disposal. The fermenter contains stationary cages with perforated base for the fixed bed. The produced hydrogen biogas is injected into the fermenter by a multi-part tubing system, which is attached below the cages in each case, without an agitator. The fermenter is implemented in a double-walled manner and the double wall is filled with a barrier fluid concerning hydrogen (e.g. ionic liquids). A dry fermentation is percolate. The fermentation is dark fermentation. The process stability and gas productivity are significantly increased by implementing weak intensities influencing on the microorganisms and wavelength-selective optical illumination with a band width of 3-150 nm, an irradiation strength of 0.1-50 W/m2 and wavelength of 400-540 nm (blue light) or of 850-650 nm (red light). The fermentation process and the optical illumination are carried out by an intelligent regulator to improve micro-biological process stability and to increase the total gas quantity and the hydrogen concentration in the developing gas. The regulation is carried out on the basis of automatic controller. A conventional controller is combined with an external loop, which receives control error as input parameter and adjusts on the basis of its regulation parameter of an internal loop. The regulation process uses the actual value, pH value, hydrogen-gas quantity and hydrogen concentration as input parameters. The hydrogen-gas quantity and hydrogen concentration are summarized to the hydrogen rate. A priority regulation target is the stabilization of the pH value and maximization of the hydrogen rate. The quantity and the time intervals of the substrate supply are used as correcting variables. The adaptive regulation process uses a fuzzy controller. The regulation process is adjusted, so that acetic acid and/or butyric acid production rate is maximized.    DESCRIPTION OF DRAWING(S) - The figure shows a sectional representation of a biohydrogen fermenter with a rotating drum insert.    Fermentation container (20)    Rotational axis (21)    Perforated cylinders (24)    Substrate outlet (25a, b)    Device for gas injection. (27)