In the light of increasing fears about climate change, greenhouse gas mitigation technologies have assumed growing importance.Carbon capture and sequestration (CCS) is one of the options that can enable the utilization of fossil fuels with lower CO2 emissions.Among the different technologies for CO2 capture,capture of CO2 by chemical-looping combustion (CLC) is the technology that is closest to commercialization.While a number of different fuels and oxygen carriers are used in chemical-looping combustion for power production and CO2 capture have been proposed, a few studies have been done biomass as solid fuels and man-made ferro oxides as a oxygen carriers in the chemical-looping combustion (CLC).This thesis focuses on developing a consistent framework for an objective comparison of the performance of oxygen carriers with biomass for cyclic operation conditions.This framework has been applied to evaluate the performance of oxygen carriers, ferro oxides which is Fe2O3 ％70-Al2O3 ％ 30 as inert materials and pine saw dust as biomass.Chemical-looping combustion (CLC) is a novel combustion technology with inherent separation of the CO2 which is a greenhouse gas and has effect on climate change.A metal oxide or mixed metal oxides with inert binder as support material as an oxygen carrier which transfers oxygen from combustion air to the fuel.So, a direct contact between air and fuel is avoided.Two interconnected fluidized beds reactor systems, having a fuel reactor and an air reactor, are used in the process.In the air reactor; the reduced metal oxide is oxidized with air and in the fuel reactor, the metal oxide is reduced by the reaction with the fuel.The outlet gas from the fuel reactor consists of CO2 and H2O.When water is condensed, almost pure stream of CO2 is obtained.Considerable amount of researches have been conducted on CLC with respect to oxygen carrier development, reactor design, cold system, thermodynamic analysis, system efficiencies and prototype testing.The technique has been demonstrated successfully with both natural gas, syngas as gaseous fuels and coal, biomass as solid fuels in continuous prototype reactors based on interconnected fluidized beds within the size range 1-500 kW.Different types of oxygen carriers based on the transition metal oxides of Ni, Co, Fe, Cu and Mn are tested.From these tests it can be seen that almost complete conversion of the fuel can be obtained and 100％ CO2 capture is possible.Considerable amount of researches have been conducted on CLC with respect to oxygen carrier development, reactor design, cold system, thermodynamic analysis, system efficiencies and prototype testing.The pressure profiles, gas velocities, solid circulation rate, solids flux, residence time distribution of gas and particles in the reactors and gas leakage were discussed in cold flow model studies.And the pressure profiles, gas velocities, solid circulation rate, and residence time of both reactors were measured in the experimental stage.The experiment results show that gas fluidization velocity in the air reactor is 1.8 m/s, gas fluidization velocity in the fuel reactor is 0.5 m/s, and the bed materials inventory of the two reactor is between 1.2 kg to 3.15 kg.The first cold flow model results showed that the solids circulation rates were sufficient.The appropriate operating conditions were optimized and the summary of final changes are made on cold model.The proposed design solutions are currently being tested in a cold flow model mirroring the actual interconnected fluidized bed reactor (hot) system.A comprehensive thermal investigation of oxygen carriers for chemical looping combustion has been investigated.Some metal oxides and reduced metal oxide/metal systems based on Cu, Mn and Fe show excellent characteristics and can be used as oxygen carriers in chemical looping combustion.The Fe2O3 has the advantages as oxygen carrier of being cheap and easily available, disadvantages with the iron oxides, is their relatively low oxygen ratios.But, this negative can be neutralize with their affinity to syngas (CO, H2)for biomass as Fe2O3 is one of the higher oxidation with equilibrium CO and H2 concentrations after Cu-based oxygen carriers.The Fe2O3 has also good conversion rate of CH4 to CO2 even by increasing temperature of the range 900-1500 ℃In conclusion, In the present study, we have built a interconnected fluidized bed device for chemical looping gasification of biomass.The effect of the reactor temperature on the flue gas composition and gasification efficiency and carbon conversion rate were experimentally investigated and characterizations of the iron-based oxygen carrier as fresh and used were studied by SEM, XRD, and BET.Gasification efficiency exceeds 60％ in most conditions during the 60 continuous run.The CO and H2 concentrations are increased relative to with the increase of the temperature of the fuel reactor, and CO2 concentration decreases with the increase of the temperature of both the fuel and air reactor.Biomass gasification efficiency and carbon conversion increases accordingly with the increase of the temperature of the fuel reactor, at the 900 ℃ gasification efficiency of over 78％.The feeding rate of biomass in the fuel reactor should be matching the amount of oxygen carrier circulation.After 60h with the iron-based oxygen carrier no polymorph changes, increased surface area.There was no significant sintering and crushing phenomenon.There is no significant decline in the performance of the reduction reaction, indicating that it has good stability and resistance to sintering and, suitable as a chemical looping gasification of biomass with the iron-based oxygen carrier.