NOVELTY - The biogas generating plant comprises: a tunnel fermentation chamber equipped with a biomass container; a thermally insulated base; vertical foundation walls (1); installations for moisturizing biomass with a process liquid; installations for recirculation of seepage water; an arch roof for covering spread over arch load-bearing construction (3) and supported on the vertical biomass container walls and gas-tight gable walls; and a biogas store formed by double layer of a roof covering foil with an inlet to a biogas store situated in an upper part of a fermentation chamber.    USE - The plant is useful for generating biogas for use in agricultural applications such as small farms, for cultivation of plants.    ADVANTAGE - The plant enables controlled course of methane fermentation in biogas plant and utilizes biogas for the needs of the farm in a cogeneration system.    DETAILED DESCRIPTION - The biogas generating plant comprises: a tunnel fermentation chamber equipped with a biomass container; a thermally insulated base; vertical foundation walls (1); installations for moisturizing biomass with a process liquid; installations for recirculation of seepage water; an arch roof for covering spread over arch load-bearing construction (3) and supported on the vertical biomass container walls and gas-tight gable walls; a biogas store formed by double layer of a roof covering foil with an inlet to a biogas store situated in an upper part of a fermentation chamber; and a duct fan (8) for forcing circulation of biogas to the biogas store and connected into the inlet. The foil has upper and lower layers secured on opposite sides of the arch roof covering load-bearing construction. The lower foil has gas slots (29) placed at 1/4 of the height of the arch load-bearing construction. Lower edges of the roof covering are supported on an upper part of the foundation walls of the container. The moisturizing installations have moisturizing nozzles placed in an intermediate zone depending on the height of the biomass loading zone. The biomass loading zone has a channel made of a perforated barrier supported on the base of biomass container or constituting a perforated pipe, suspended, supported or resting freely in a biomass layer. The lower edges of the roof covering: form a gas tight connection on the appropriately shaped upper part of the foundation walls that are provided with the aid of slides or guide rails comprising channel irons; and are slideably mounted in troughs executed in the upper part of vertical foundation walls, where the troughs form gas tight connections such as siphon connections of the lower edges. The moisturizing nozzles are located in the biomass loading zone on a level or at various levels between the biomass container and the upper part of the fermentation chamber. The upper part of the channel is placed at an internal pipeline for conveying pulp and placed in the lower part of the channel that is installed on an auger conveyor to convey compacted pulp to the exterior. The biomass container is equipped with aeration installations with perforated nozzles mounted in side zones at the biomass container base, supplied by an aeration pipeline. A coil is placed in the biomass layer to remove surplus heat from the fermentation chamber. The rigid arch load-bearing construction is placed in a gas-tight foil sleeve for insulating the construction from the gaseous atmosphere in the biogas store. The foil sleeve has inspection openings for inlet of appropriate gases for protecting the construction against deterioration and for controlling moisture of the atmosphere inside the sleeve. The foundation walls are made of a brickwork or thermoinsulating panels, and are placed between pillars. An INDEPENDENT CLAIM is included for an installation to produce and utilize biogas.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a biogas generating plant.    Essentially vertical foundation walls (1)    Arch load-bearing construction (3)    Duct fan (8)    Heating conduit (25)    Gas slots. (29)