NOVELTY - Producing biogas involves preparing and adding raw materials into fermentation system through feed tube. Biogas is produced and gets accumulated on side wall of fermentation cylinder, which is provided with inlet and outlet. The adjacent side wall is provided with gas panel board. The slurry is extruded into primary fermentation pipeline, from where slurry flows to first guide pipe (22) and then to second guide pipe (24) and finally into secondary fermentation pipeline. Within the secondary fermentation pipeline, biogas is produced and accumulates on inlet and outlet, present on the side wall.    USE - Method for producing biogas by using fermentation system (claimed).    ADVANTAGE - The method enables to produce biogas in large amount.    DETAILED DESCRIPTION - Producing biogas involves preparing and adding raw materials into fermentation system through feed tube. Biogas is produced and gets accumulated on side wall of fermentation cylinder, which is provided with inlet and outlet. The adjacent side wall is provided with gas panel board. The slurry is extruded into primary fermentation pipeline, from where slurry flows to first guide pipe and then to second guide pipe and finally into secondary fermentation pipeline. Within the secondary fermentation pipeline, biogas is produced and accumulates on inlet and outlet, present on the side wall. The adjacent side wall is provided with air resistance plate (14). The slurry from secondary fermentation pipeline flows into secondary feed tube (42), then from outlet pipe (44) flows in bacteria containing apparatus. The slurry from bacteria containing apparatus flows into drainage pipe and when the slurry has reached to lowest point of drainage pipe, the slurry is drained out under hydraulic pressure. The slurry flows from third guide pipe (32) and fourth guide pipe (34) into primary fermentation pipeline storage, which is provided with secondary fermentation pipeline storage. The slurry passes through feed tube under hydraulic pressure and flows into secondary feed tube through drainage pipe. The slurry flows into bacteria containing apparatus and then into secondary fermentation pipeline. Pressure in drainage pipe is less then hydraulic pressure. The slurry due to pressure drains into feed tube and then flows into bacteria containing apparatus and finally flows into secondary fermentation pipeline. The pressure lowers down then hydraulic pressure and then, the slurry flows into secondary feed tube. The process is repeated to produce biogas.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the fermentation system.    Air resistance plate (14)    First guide pipe (22)    Second guide pipe (24)    Third guide pipe (32)    Fourth guide pipe (34)    Secondary feed tube (42)    Outlet pipe (44)