# Biomass-Based Chemical Looping Gasification: Overview and Recent Developments
## 6 Conclusions and Future Prospects  
Biomass has been considered as a potential renewable source to replace fossil fuels for energy generation and chemical production. Due to the carbon cycle of biomass, the use of biomass as a feedstock can achieve significant environmental benefits of mitigation of net greenhouse gas emissions. However, biomass is currently less attractive in conventional thermochemical processes since it owns low energy density, high moisture content, complex ash composition, and highly distributed resource. The comprehensive summary of biomass chemical looping gasification basis and its developments through recent studies will be of great benefit for the readers. This study is structured to investigate key components in a BCLG process. Therefore, through the existing knowledge and recent research, the potentials and challenges of BCLG are summarized in this study, as follows:  
* Description of principles and developments of biomass-based chemical looping gasification technology. * Recent research strategies and achievements in biomass-based chemical looping gasification. * Prospects and challenges of biomass-based chemical looping gasification towards commercialization. As discussed in the study, chemical looping technology can produce high-quality syngas using for energy generation or chemical production. Thus, using biomass as a feedstock for chemical looping gasification has many potential advantages over the conventional methods in biomass conversion and coal-fueled chemical looping processes. However, the chemical looping technologies are mostly in the R&D phase since they remain several challenges. Oxygen carrier is a key factor in the chemical looping concept, the selection of suitable oxygen carrier materials is one of the most important issues in terms of redox behavior, stability, availability, process performance, costs, environmental, and safety aspects. Additionally, tar formation from biomass chemical looping gasification has been considered increasingly. Tars formed during the process cause serious problems for the BCLG system, resulting in a decrease in the process efficiency. However, research on tar formation and elimination in BCLG is still limited. A better understanding of tars and finding efficient approaches to minimize their effects on the system are necessary for the commercialization of BCLG. Numerous studies on the chemical looping process of biomass have been carried out over the years, and many various carriers were investigated in a pilot-scale system of chemical looping gasification plants for their feasibility. The recent developments of biomass CLG have been carried out on a pilot-scale system ranging from a few kW to MW. This is the basis for the massive scale-up of the process that is necessary for commercial power plant and syngas production along with CO\({}_{2}\) capture. Furthermore, syngas cleanup technologies have been improving to mitigate problems regarding failure and blockage, as well as the loss of efficiency. Additionally, economic evaluation for each specific biomass feedstock, operational flexibility in the variation of feedstock composition is to respond to the changes in supply and demand of the feedstock market [9]. Those challenges should be solved to meet the coming future regarding the commercialization of this technology. Hence, chemical looping gasification using biomass as feedstock shows promising applications in the future in the continued fight against climate change [2]. [PERSON] is responsible for administration, conceptualization, the original draft, and the applied methodology. [PERSON] supported the writing process with his review and edits. [PERSON] supported the writing process with his review and edits. [PERSON] supervised the research progress the presented work. All authors have read and agreed to the published version of the manuscript. **Funding:** This work received no external funding. The corresponding author would like to thank the Technical University of Darmstadt, enabling the open-access publication of this paper.