Rice husk ash is a waste from biomass power plants. Thus, the characterization and utilization of rice husk ash for silicon source was studied showed in this research. X-ray Diffractometer (XRD), X-ray Fluorescence Spectrometer (XRF), and Scanning Electron Microscope (SEM) techniques were used to examine the components of rice husk ash before and after extraction. Initially, components from rice husk ash were investigated using the XRF technique, which revealed a silicon (Si) value of 89.22%. Furthermore, trace metals detected in rice husk ash include K (7.27%), Ca (1.68%), Mn (0.33%), and Fe (0.25%). Geographical conditions and the year of rice harvest contributed to differences in composition. Hydrothermal and silica precipitation techniques were used to extract silicon from rice husk ash. Finally, XRD, XRF, and SEM techniques were used to examine silica/silicon dioxide (SiO2). The component of silicon dioxide (SiO2) recovered from rice husk ash extraction in NaOH 3M and HCl 2M conditions was 80.2%. The amorphous form of silicon dioxide (SiO2) generated from rice husk ash is used in a range of industries, including petroleum, rubber, catalyst compounds, construction materials, desiccant, and food. As a result of this research, a waste utilization concept and increased value from rice husk ash was developed, resulting in a circular economy in biomass power plants as well as good health and well-being (Sustainable Development Goal: SDG3) for the community.