## 4 Summary and Conclusions  
In this study, development of biomass gasification technology with fluidized-bed reactors were conducted to examine the syngas composition under various operating conditions and different structural configuration. Gasification experiments of biomass were performed to investigate the potential means for the enhancement of hydrogen generation. Figure 16: Distribution ratio of bed sand in combustor under different operating conditions (the values of \(u_{\rm v}/u_{\rm mf}\) are shown as legend in the plots). Conventionally, air is supplied to the reactor as gasification medium. Alternatively, steam or oxygen-rich gas can be utilized to improve the syngas characteristics. Baseline experiments with various operating parameters, including air equivalence ratio (ER) and temperature, were firstly performed in the 30 kWth bubbling fluidized-bed (BFB) gasifier commissioned at INER. Then, trial tests were conducted with the aforementioned operational factors. The test data to address the influence of steam showed that hydrogen generation was enhanced with an additional steam injection to the reactor. It was seen that the existence of steam promoted the water-gas shift (WGS) reaction to generate a higher hydrogen content in the syngas composition. Furthermore, oxygen-rich gas improved the gasification process towards more fractions of both H2 and CO in the syngas. Two types of reactor configuration based on \"indirect gasification technology\", namely dual fluidized beds (DFB) and interconnected fluidized beds (IFB), were surveyed in the present work. To start with, the cold-flow models were generally utilized to visualize and comprehensively study the hydrodynamic characteristics, which can facilitate subsequent investigation into thermo-chemical processes for testing in the hot models. A series of efforts on DFB were undertaken at INER, where both the cold model and hot model were commissioned. The pilot test facilities of the latter were just established with verified functional tests for unit operation, while follow-up experiments with in situ operating conditions will be pursued in the near future. For the former, dimensionless analysis and comprehensive hydrodynamic testing were carried out systematically. It was confirmed that the circulation mass of the bed material driven by the flow rate of the operating air exceeded the design value, which gave a comfortable safety factor of the engineering design. In addition, the average pressure distribution measured by the system-wide cyclic operation was similar to that of the published literature. In summary, the outcome demonstrated the applicability of this cold model. The experimental results from the cold model of DFB can provide the guidance for testing the subsequent DFB hot model. Further efforts will be pursued to establish databases for gasification reaction performance and optimal operating parameters. The outcome would be beneficial to extensive research on clean energy and carbon abatement technologies. Conceptualization, Y.-P.C. and K.-T.W. ; methodology, D.-M.C. and Y.-P.C. ; software, D.-M.C. and R.-Y.C. ; validation, P.-C.C. ; formal analysis, H.-Y.C. ; investigation, D.-M.C., P.-C., H.-Y.C., and R.-Y.C. ; resources, Y.-P.C. ; data curation, Y.-P.C. ; writing, original draft preparation, D.-M.C. and P.-C.; writing, review and editing, Y.-P.C. and K.-T.W. ; visualization, K.-T.W. ; supervision, Y.-P.C. and K.-T.W. ; project administration, Y.-P.C. ; funding acquisition, Y.-P.C. All authors have read and agreed to the published version of the manuscript. This research was supported by the governmental R&D funding allocated to the Institute of Nuclear Energy Research (INER), Atomic Energy Council, and Ministry of Science and Technology with the grant numbers: MOST 108-3111-Y-042A-122 and MOST 108-3116-F-008-004 -CC1.