NOVELTY - Collecting and pyrolyzing biomass involves collecting the biomass from a growth site using a mobile unit. The biomass is continuously fed into a pyrolysis apparatus accommodated by mobile unit, as the mobile unit is moved across the growth site. While the biomass is processed in the pyrolysis apparatus, further biomass is simultaneously being collected.    USE - For collecting and for producing a pyrolysis liquid and/or char from the biomass (claimed).    ADVANTAGE - The method avoids transportation of relatively large volumes of biomass from the growth site to a remote pyrolysis facility. As pyrolysis liquid has a significantly higher energy concentration per volume than biomass, a certain amount of energy requires less space when present in the form of pyrolysis liquid than when present in the form of biomass, and the energy may thus be more conveniently conveyed to the intended consumer in the form of pyrolysis liquid. The engine or motor of the mobile unit may utilize the pyrolysis gas, pyrolysis liquid and/or char as fuel, thus reducing or even eliminating the need for a separate fuel source of the mobile unit. The method does not require inert gas for fluidization and heat transport, thus reducing overall dimensions of the apparatus at a given capacity. The method does not require sand as heat transport or heat transmission medium, thus reducing wear and tear and eliminating the need for subsequent separation of sand and char. Due to rotational motion imparted on the biomass in centrifuge chamber, the area of the outer wall of the centrifuge chamber is in contact with the biomass, while centrifugal forces ensure an even pressure of biomass towards the outer wall, thus ensuring improved utilization of the reactive surface in the pyrolysis apparatus and consequently higher specific capacity. As the char particles are forced towards the wall by centrifugal forces and gas may be filtered by passage from the outer wall of the centrifuge chamber through a layer of biomass to an inner wall of the centrifuge chamber, the need for a separate cyclone may be eliminated. Additionally, as biomass is forced towards the reactive surface, the need for additional device for imparting the biomass is reduced, thus reducing wear and tear and consequently maintenance costs. Due to the rotational layout of the centrifuge chamber and rotor, there is no need to adjust e.g. angles of blades or distance between blades and a tube wall, as in certain prior art devices. Further, contact between metal parts may be eliminated, and contact between metal parts and biomass strongly reduced, as the rotating motion is imparted on the biomass particles. Operation is accordingly less vulnerable to changes in biomass material properties, such as particle size distribution and humidity as well as to fluctuations of biomass feeding speed to the reactor. As char is conveyed away from the reactor, high heat conduction between the reactor wall and the biomass material is ensured, resulting in improved efficiency and improved pyrolysis liquid yield. The improved pyrolysis yield is conferred by a steep temperature gradient in the biomass material.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a mobile unit for collecting biomass and for producing pyrolysis liquid from the biomass comprising biomass collector, biomass conveyor, and pyrolysis apparatus that are operable such that the pyrolysis apparatus can decompose the biomass, while further biomass is simultaneously collected from the growth site using biomass collector.