Combining experimental and analytical methods to evaluate coal co-firing with sorghum waste

Coal is the primary fuel for most Indonesian power plants, causing high CO2 emissions. Since the Paris Agreement prioritizes efforts to reduce CO2 emissions, power generation companies have put great efforts into demonstrating co-firing of coal with biomass. This research is the first study to examine the synergistic effect of combining coal and sorghum during co-firing. To complete this investigation, an experimental setup was carried out utilizing a drop tube furnace equipment that creates ash deposits, followed by X-ray diffraction (XRD) analysis to acquire the crystallinity parameters and characterization. Based on the parameters of derivative thermogravimetry, Rmax, sample residue, root mean square of synergistic occurrence, ash deposit, insufficient crystallinity, amorphous content, and crystal structure, namely C5, C10, C15, C20, and C25 (representing the sorghum ratios of 5 10, 15, 20, and 25%, respectively), the grey relational grade analysis provides recommendations for the implementation of a mixture of coal and sorghum co-firing. The thermogravimetric analysis revealed that 10% of sorghum in the fuel mixture (namely C10) was the best recommendation for mixing with coal in terms of the activation energy (111 kJ mol−1) with an error deviation close to zero. Overall results from thermogravimetric to XRD analyses indicate recommendations for co-firing coal and sorghum in the sequence of C10, C15, C5, C25, and C20.