# Biomass-Based Chemical Looping Gasification: Overview and Recent Developments
## 5 Progress in Biomass Chemical Looping Gasification
### Simulation/Modeling Studies
Computational methods (using ChemCAD software) based on mass and energy balances were used for in-depth techno-economic analysis. The influence of various technical and economic parameters on economics was considered through the sensitivity study. A 7-\(\text{MW}_{\text{th}}\) CLG system was simulated to compare with conventional gasification processes using ASPEN Plus [137]. The CLG consists of a bubbling fluidized-bed gasifier and a fast fluidized-bed oxidized. Along with the comparison in the process performance, the economic aspects were also evaluated in the study. The results showed that the CLG system had a higher total capital investment compared to that of the conventional gasification process with pure oxygen but the annual operating cost of the CLG is $0.58M less resulting in the CLG as a feasible solution for biomass gasification. [PERSON] et al. [138] developed a biomass direct chemical looping process (BDCL) for hydrogen and electricity co-production based on a multistage model using ASPEN Plus. The BDCL process configuration consists mainly of biomass preparation, the chemical looping system, heat recovery and steam generation (HRSG), gas cleanup units, and power generation systems. The BDCL process can produce hydrogen and/or electricity at any ratio, and it is 10-25% more efficient compared to conventional biomass combustion and gasification processes. The BDCL process also generated a high CO\({}_{2}\) concentration stream which could lead to a carbon-negative process from the life cycle standpoint. A system of biomass-based integrated gasification combined cycle coupling with CLG (CLG-BIGCC) for power generation was simulated by [PERSON] et al. [139]. The system, mainly consisting of BCLG, gas cleaning, heat recovery steam generator (HRSG), and gas/steam turbine cycles, was developed with ASPEN Plus software. The simulation results were compared with the experimental data from a 25 \(\text{kW}_{\text{th}}\) interconnected fluidized bed reactor under the same operating conditions. The power efficiency of the CLG-BIGCC system was 33.51%, the gas turbine efficiency obtained 33.24% and the efficiency of the steam turbine was 34.01%. Those efficiencies are higher than the existing BIGCC plants in China with a range of 30-32%. Moreover, a sensitivity analysis on the CLG-BIGCC was carried out to obtain the optimal gasification conditions, and five optimization schemes about CLG-BIGCC with nitrogen reinjection were proposed and investigated. [PERSON] et al. [140] developed a new system for the co-production of electricity and hydrogen with CO\({}_{2}\) capture using biomass as fuel. The model integrated a biomass steam gasification (BSG) with an iron-based chemical looping hydrogen production (CLHP) system and a combined heat and power (CHP) system. The fuel used in the study was raw wood (RW) and torrefied wood (TW). The results were used to evaluate the effects of operating conditions on the process performance and syngas derived from RW and TW. Using TW can improve the BSG-CLHP-CHP system's performance. Hydrogen thermal efficiency and hydrogen yield of TW-derived syngas increased by 8.3% and 22%, respectively. [PERSON] et al. [141] developed a numerical model to investigate biomass gasification with iron-based oxygen carrier in a bubbling bed reactor. The model integrated the Eulerian multi-fluid model and the chemical reaction models including the decomposition of biomass, gasification of char, water-gas-shift reaction and the heterogeneous reactions between gases and metal oxides. It is validated well by the experimental data from the literature. The results were used to analyze the impacts of the mixing and segregation behaviors between two solid phases on the gas composition distribution at various operating conditions. A one-dimensional transient model, including the hydrodynamics and chemical reactions, was developed for biomass gasification using chemical looping technology to investigate the outlet concentrations of gaseous species and efficiencies at various operating conditions [142].