The method comprises providing plant residue having a shell portion (90 wt.%), partially hydrolyzing constituents of the plant residue including carbohydrate, fat and/or protein, and separating liquid phase into dissolved components and solid phase. A suspension is provided for the hydrolysis of the plant residue in a solvent such as water (40 wt.%). The hydrolysis is performed at a temperature of 30-38[deg] C and performed with addition of enzymes, acid or base having a pH of 5.5 and inoculant microorganisms. The method further comprises washing, sterilizing and drying the solid phase. The method comprises providing plant residue having a shell portion (90 wt.%), partially hydrolyzing constituents of the plant residue including carbohydrate, fat and/or protein, and separating liquid phase into dissolved components and solid phase. A suspension is provided for the hydrolysis of the plant residue in a solvent such as water (40 wt.%). The hydrolysis is performed at a temperature of 30-38[deg] C and performed with addition of enzymes, acid or base having a pH of 5.5 and inoculant microorganisms. The method further comprises washing, sterilizing and drying the solid phase. The liquid phase is transferred as an energy-rich liquid for a biogas plant. An independent claim is included for a system for processing plant residue.
