Bioenergy potential of Kauayan tinik (Bambusa spinosa Roxb.) and Kauayan kiling (Bambusa vulgaris Schrad. ex J.C.Wendl): Culm height section analysis

This study evaluated the energy potential of two Philippine bamboo species, Bambusa spinosa (known locally as Kauayan tinik) and Bambusa vulgaris (known as Kauayan kiling), by analyzing moisture content, relative density, proximate composition, ash basic oxide composition, gross calorific value and energy density across different culm height sections (bottom, middle and top). Moisture content significantly decreased from bottom to top, while relative density showed the opposite trend, with a strong negative correlation observed, particularly in B. spinosa . Proximate analysis revealed that the bottom and middle sections of both bamboo species had higher volatile matter and fixed carbon, along with lower ash content. In both bamboo species, the ash contained more CaO than MnO and Fe2O3, while the top section of the culm had the lowest levels of all identified basic oxide components. This top section also exhibited the highest energy density, suggesting greater potential suitability for biomass energy generation. • Moisture content significantly decreased from bottom to top, while relative density showed the opposite trend, with a strong negative correlation observed, particularly in the botto section of B. spinosa (R² = 0.99). • Proximate analysis revealed that the bottom and middle sections of both bamboo species had higher volatile matter and fixed carbon, along with lower ash content. • The ash composition of both bamboo species showed higher CaO content compared to MnO and Fe2O3, while the concentrations of all identified basic oxide components were lowest in the top section of the culm. • Despite lower gross calorific values, the top sections of both species had the highest energy density due to higher relative density. • The correlations between energy density and proximate analysis components showed stronger correlations in B. spinosa , particularly in the middle sections (volatile matter and ash) and between energy density and fixed carbon content in the top section.