Composite preparation from various biomasses and biochar blended natural rubber (NR) as a binder was produced for proposing an alternative fuel energy rod. Rice straw (RS), sugarcane bagasse (SC), and corncob (CC) were combined with different NR ratios. Properties of the composites, in terms of tensile, impact, and compressive strengths, together with flammability, thermal stability, and heat-releasing analyses from Higher Heating Value (HHV) and Ultimate Analysis (CHN-S), were interpreted. It was found that the increase of NR constituent improves the mechanical properties and HHV. The minimization of NR needs to be designed for the release of carbon monoxide. During the mixing operation with an internal mixer and a two-roll mill, no differences were observed in composites with RS, SC, and CC, and the optimal biomass is 80 phr. After transferring to biochar, the produced composite clarifies the usability of the energy rod using pure NR as the natural binder.