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, R_max, 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. Graphical abstract: [Figure not available: see fulltext.]