NOVELTY - Capturing carbon dioxide from the combustion of char produced in biomass pyrolysis, comprises: (a) pyrolyzing biomass in a pyrolysis reactor (22); (b) separating the pyrolysis oil vapors and transferring the char and heat energy carrier particles; (c) combusting the char in the char combustor (24); (d) separating the flue gas stream; (e) separating the gas stream and capturing a stream of carbon dioxide; (f) oxidizing a first portion of the stream of the carrier particles; and (g) recycling to the pyrolysis reactor of a second portion of the stream of the carrier particles.    USE - The method and system are useful for capturing carbon dioxide from biomass pyrolysis (claimed) for producing pyrolysis oil, which is useful for obtaining transportation liquids, chemicals or chemical feedstock.    ADVANTAGE - The method provides pyrolysis oil with better quality, in which the pyrolysis oil is stable during its transportation and does not deteriorate.    DETAILED DESCRIPTION - Capturing carbon dioxide from the combustion of char produced in biomass pyrolysis, comprises: (a) pyrolyzing biomass in a pyrolysis reactor (22) in the presence of heat energy carrier particles including metal oxide sorbents to produce char, pyrolysis oil vapors and metal oxide sorbents; (b) separating the pyrolysis oil vapors from the char and heat energy carrier particles and transferring the char and heat energy carrier particles to a char combustor; (c) combusting the char in the char combustor (24) in the presence of oxidized metal oxide sorbents and producing a flue gas stream of carbon dioxide and water vapor and a stream of heat energy carrier particles including reduced metal oxide sorbents; (d) separating the flue gas stream from the stream of heat energy carrier particles including the reduced metal oxide sorbents; (e) separating the flue gas stream into carbon dioxide and water vapor and capturing a stream of carbon dioxide; (f) oxidizing a first portion of the stream of heat energy carrier particles including reduced metal oxide sorbents received from the char combustor in an oxidation reactor (26) in the presence of air to produce a regenerated stream of heat energy carrier particles including oxidized metal oxide sorbents to be used in step (c); and (g) recycling to the pyrolysis reactor of step (a) a second portion of the stream of heat energy carrier particles including reduced metal oxide sorbents. An INDEPENDENT CLAIM is included for a system for capturing carbon dioxide from the combustion of char produced in biomass pyrolysis, comprising a pyrolysis reactor which utilizes heat energy carrying particles including metal oxide sorbents to heat and pyrolyze a biomass producing a stream of pyrolysis oil vapors and other off gases, and char and the heat energy carrying particles, a char combustor for receiving char and the heat energy carrying particles from the pyrolysis reactor and for combusting the char with oxygen received from oxidized metal oxide sorbents to produce a flue gas stream containing carbon dioxide and water vapor and the stream, a separator for separating carbon dioxide from the water vapor to produce a stream of carbon dioxide to be sequestered, an oxidation reactor for oxidizing, in the presence of air, a first portion of the stream of heat energy carrying particles received from the char combustor to produce the stream of heat energy carrying particles used in the char combustor for combusting the char, where a second portion of the stream of heat energy carrying particles from the char combustor is recycled to the pyrolysis reactor to provide heat for the pyrolysis of biomass.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a biomass pyrolysis system that pyrolyzes biomass and employs chemical looping combustion of char.    Pyrolysis system (20)    Pyrolysis reactor (22)    Char combustor (24)    Oxidation reactor (26)    First stream. (30)