NOVELTY - Biomass (140) is processed by (a) fermenting 1st portion (101) of biomass into biogas (103) and digestate; (b) separating digestate (105) into liquid fraction (107) and solid fraction (109); (c) separating nutrients (115) from liquid fraction of digestate and adding nutrients to ash obtained in step (e) or to residue obtained after gasification in step (e); (d) drying solid fraction of digestate; and (e) incinerating dried solid fraction into ash or gasifying dried solid fraction of digestate; and optionally, (f) converting biogas obtained in step (a) into electricity and residual heat.    USE - Processing of biomass for use as dry biofertilizer and for electricity production (all claimed).    ADVANTAGE - The method can increase (green) energy production, particularly (green) electricity production. The use of thermal energy released by incineration for (green) electricity production results in a higher yield than direct incineration of the biomass because the biomass is dried before incineration, allowing wet biomass to be efficiently incinerated while generating green electricity. The yield can be increased further by converting the biogas formed in fermentation of the biomass into electricity and residual heat, and then converting residual heat, together with the thermal energy from the incineration process, into electricity and residual heat. The yield can also be increased by gasifying the biomass, instead of incinerating, with the resulting gas fraction being further converted into electricity and residual heat. Optionally, residual heat, together with residual heat obtained by converting biogas into electricity, can further be converted into electricity and residual heat to increase the yield even further.    DETAILED DESCRIPTION - Biomass is processed by (a) fermenting 1st portion of biomass into biogas and digestate; (b) separating digestate into liquid fraction and solid fraction; (c) separating nutrients, preferably nitrogen (N), from liquid fraction of digestate and adding nutrients to ash obtained in step (e) or to residue obtained after gasification in step (e); (d) drying solid fraction of digestate; and (e) incinerating dried solid fraction of digestate into ash or gasifying dried solid fraction of digestate; and optionally, (f) converting biogas obtained in step (a) into electricity and residual heat, and (g) converting heat released in incineration in step (e) and residual heat obtained in step (f) into electricity, and residual heat of conversion of gas fraction obtained after gasification in step (e) into electricity (148) and residual heat (146). INDEPENDENT CLAIMS are included for:    (1) production of biofertilizer (142), preferably dry biofertilizer, which involves using the ash obtained in step (e) or the residue obtained after gasification of step (e);    (2) use of ash obtainable by processing method of biomass or the residue obtained after gasification as biofertilizer, preferably dry biofertilizer;    (3) biofertilizer, preferably dry biofertilizer, comprising the ash obtainable by the processing method of biomass or the residue obtained after gasification; and    (4) system (100) for processing biomass comprising fermentation unit (10), separating unit (12) for separating digestate into solid and liquid fractions, and a unit (14) for separating nutrients, preferably nitrogen (N), from liquid fraction of the digestate, preferably an evaporation unit or a steam stripper, drying unit (20), and incineration unit (30) or gasification unit.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the system for processing biomass.    Fermentation unit (10)    Separating unit (12)    Unit for separating nutrients (14)    Drying unit (20)    Incineration unit (30)    System for processing biomass (100)    1st portion of biomass (101)    Biogas (103)    Digestate (105)    Liquid fraction (107)    Solid fraction (109)    Nutrients (115)    Biomass (140)    Biofertilizer (142)    Residual heat (146)    Electricity (148)