# Biomass-Based Chemical Looping Gasification: Overview and Recent Developments
## 5 Progress in Biomass Chemical Looping Gasification
### Thermodynamic Analysis and Kinetic Studies  
Thermodynamic and kinetic studies are to evaluate the energy efficiency of the system and the effects of operation parameters on process performance and the interaction between solid fuel and oxygen carriers, as well as the feasibility of oxygen carrier for chemical looping gasification of biomass. The results obtained will be analyzed to develop pilot-scale and then industrial processes by mostly using thermogravimetric analysis equipment (TGA). Various types of oxygen carriers and their compounds have been investigated to assess their feasibility for the chemical looping gasification process. Many studies have been carried out to analyze the reactivity of an oxygen carrier in various atmospheres and to propose kinetic models to describe the kinetics of the oxygen carrier with different types of fuels [94; 96; 122; 123; 124; 125; 126; 127]. During biomass chemical looping gasification, many gas-solid reactions take place simultaneously in the reactor. Therefore, the knowledge of redox reaction kinetics and their mechanism is necessary for the design of the system [124; 125; 128]. [PERSON] et al. [122] analyzed system performances of biomass-coal co-gasification with steam. In the study, a coal and biomass-based chemical looping power generation system was developed. Wheat straw and coal were introduced into the reactor to gasify with steam, then the generated syngas would reduce Fe\({}_{2}\)O\({}_{3}\) in the reducer. FeO generated from the reducer was oxidized by steam to produce hydrogen, and Fe\({}_{3}\)O\({}_{4}\) generated in the oxidizer would be regenerated to form Fe\({}_{2}\)O\({}_{3}\) before the next cycle. Hydrogen obtained in the oxidizer then was used as feedstock to generate electric power through the SOFC system. The result of the study was used to analyze the efficiency of energy and exergy of the system, the effect of operation parameters on system performance, and economic feasibility for the removal of NO\({}_{\omega}\), SO\({}_{\omega}\), and CO\({}_{2}\). [PERSON] et al. [125] discussed the mechanism of reactions between corn cob and Mn\({}_{2}\)O\({}_{3}\) during the chemical looping gasification. Furthermore, the method of Gibbs free energy minimization was used to analyze the thermodynamics of syngas generation from the process. They proposed the optimal ratio of Mn\({}_{2}\)O\({}_{3}\)/corn cob is 0.18 to obtain the maximum yields of H\({}_{2}\) and CO, and the total dry concentration of CO and H\({}_{2}\) could gain 98.8% at 1000 \({}^{\circ}\)C and atmospheric pressure. Additionally, the carbon conversion also increases in the presence of steam used as a gasifying agent. Non-isothermal experiments were carried out by [PERSON] et al. [128] to develop the kinetic analysis of oxygen carrier reduction by char. A mixture of biomass char and NiFe\({}_{2}\)O\({}_{4}\) as oxygen carrier was introduced into the TG-MS system and then heated to 1250 \({}^{\circ}\)C with different heating rates under the inert environment. The study investigated that the increase of activation energy of redox reaction corresponds to conversion ratio, and the random nucleation and subsequent growth model can be used to describe the kinetic mechanism. A new concept for syngas production was proposed to use a liquid metal oxide as an oxygen carrier for chemical looping gasification. The proposed configuration comprises two interconnected bubble reactors as the fuel and air reactors, and a liquid form of oxygen carrier is circulated between two reactors to provide the required heat and oxygen for the gasification reaction. The proposed concept could prevent the challenges from the solid oxygen carrier system such as agglomeration and sintering. [PERSON] et al. [94] carried out a thermodynamic analysis to investigate the performance of four bimetallic oxygen carriers (BaFe\({}_{2}\)O\({}_{4}\), BaMn\({}_{2}\)O\({}_{4}\), CaFe\({}_{2}\)O\({}_{4}\), CaFe\({}_{2}\)O\({}_{4}\)) for CLG of biomass-based lignin.