The invention relates to a method and a system for obtaining biogas in two or more stages in a hydrolysis and a methane stage, wherein the hydrolysis of solid biogenic materials is performed in at least two percolators operated at offset times. Liquid hydrolyzate and CO2 rich hydrolysis gas, and then hydrolysis gas comprising methane thereby arises in the percolator. The liquid hydrolyzate is removed from the percolators, wherein part of the hydrolyzate is fed into the methane stage and the other part of the hydrolysis stage. In the methane stage, the hydrolyzate is converted to biogas and fermenting fluid. In the method according to the invention, the percolators are operated in a gas tight manner and hydrolysis gas is drawn off from the percolators, wherein the hydrolysis gas comprising methane is fed to an energy utilization and CO2 rich hydrolysis gas is used for purging a further percolator operated at an offset time. The system according to the invention is suitable for performing said method and comprises at least two gas tight percolators that are interconnected by means of the gas supply lines thereof, and at least one methane reactor.