Method for processing biomass, comprising the steps of for ensuring homogenous particle distribution of biomass feedstock chipping the initial size of the biomass feedstock to a particle size of maximum 10 cm, measuring the moisture content of the biomass feedstock chipped to processing size and reducing the measured moisture content of the biomass feedstock by drying so as to fall below 12%, preheating a drying air stream (a) used for drying the feedstock, before feeding a first portion of dried feedstock into a heat treatment roasting furnace, evacuating the interior of the roasting furnace, heating the interior of the roasting furnace to a temperature in the range of 220-300 °C, predetermined in function of a target calorific value of an end-product, feeding dried feedstock into the roasting furnace, for producing an end-product, roasting the feedstock fed into the roasting furnace by continuously maintaining a pressure exceeding 1.0 bar(a) by maximum 200 mbar(a) in the roasting furnace, disposing of gaseous media released during roasting, where disposing of the gaseous media released during roasting includes the utilisation of the gaseous media by burning, transmitting the end-product from the roasting furnace to a cooler, cooling the end-product to below its ignition temperature, discharging the cooled end-product from the cooler for further utilisation, pre-cooling a cooling medium stream (f) used for cooling the end-product by the drying air stream (a) used for reducing the moisture content of the feedstock, characterised in that feeding dried feedstock into the roasting furnace comprises feeding the dried feedstock in portions into the roasting furnace via a vacuum-batching unit, providing periodically closure of an interior of the vacuum-batching unit by closing an outlet of the interior of the vacuum-batching unit by a controllable closing valve and by closing an inlet of the interior of the vacuum-batching unit in a gas-tight manner by a controllable gas-tight closing valve, vacuum-pumping each feedstock portion led into the closed charging area of the vacuum-batching unit, the step of preheating the drying air stream (a) used for drying the feedstock comprises at least one of preheating by a heating medium stream (e) discharged from the roasting furnace, preheating by warmed-up cooling medium stream (f) used for cooling the end-product, preheating by heat energy developing while burning the gaseous media generated during roasting. for ensuring homogenous particle distribution of biomass feedstock chipping the initial size of the biomass feedstock to a particle size of maximum 10 cm, measuring the moisture content of the biomass feedstock chipped to processing size and reducing the measured moisture content of the biomass feedstock by drying so as to fall below 12%, preheating a drying air stream (a) used for drying the feedstock, before feeding a first portion of dried feedstock into a heat treatment roasting furnace, evacuating the interior of the roasting furnace, heating the interior of the roasting furnace to a temperature in the range of 220-300 °C, predetermined in function of a target calorific value of an end-product, feeding dried feedstock into the roasting furnace, for producing an end-product, roasting the feedstock fed into the roasting furnace by continuously maintaining a pressure exceeding 1.0 bar(a) by maximum 200 mbar(a) in the roasting furnace, disposing of gaseous media released during roasting, where disposing of the gaseous media released during roasting includes the utilisation of the gaseous media by burning, transmitting the end-product from the roasting furnace to a cooler, cooling the end-product to below its ignition temperature, discharging the cooled end-product from the cooler for further utilisation, pre-cooling a cooling medium stream (f) used for cooling the end-product by the drying air stream (a) used for reducing the moisture content of the feedstock, characterised in that feeding dried feedstock into the roasting furnace comprises feeding the dried feedstock in portions into the roasting furnace via a vacuum-batching unit, providing periodically closure of an interior of the vacuum-batching unit by closing an outlet of the interior of the vacuum-batching unit by a controllable closing valve and by closing an inlet of the interior of the vacuum-batching unit in a gas-tight manner by a controllable gas-tight closing valve, vacuum-pumping each feedstock portion led into the closed charging area of the vacuum-batching unit, the step of preheating the drying air stream (a) used for drying the feedstock comprises at least one of preheating by a heating medium stream (e) discharged from the roasting furnace, preheating by warmed-up cooling medium stream (f) used for cooling the end-product, preheating by heat energy developing while burning the gaseous media generated during roasting.