To generate methane from biomass, a biomass pulp is produced from the biomass with a desired dry mass content being set, and the biomass pulp is placed under pressure. The biomass pulp is heated under pressure in order to liquefy the solid organic components of the biomass pulp. The pressurized and heated biomass pulp is heated further to at least the critical temperature of the biomass pulp. Solids precipitated under pressure and increased temperature are separated from the fluid phase. At least a part of the remaining fluid phase is gasified under pressure and increased temperature by means of a reactor to form a methane-rich gas.