<![CDATA[The decarbonization of coal-fired power generation cannot always be achieved through the immediate retirement of existing assets. Transition strategies are therefore required to reduce fuel consumption, emissions, and ash-related problems without compromising reliability. This review synthesizes recent developments in combustion modifiers, biomass cofiring, oxygen-carrier materials, ash utilization, and waste-derived slurry fuels. The review corpus comprises 59 bibliographic records published between 2015 and 2026, of which 53 directly relevant studies were analyzed according to their mechanisms, experimental scales, energy and environmental indicators, and operational risks. Evidence indicates that compounds containing Fe, Cu, Mn, Ti, Ca, and Mg, along with aluminosilicates, bioliquids, solid biomass, and reactive ash, act through redox catalysis, enhanced oxygen transfer, modified devolatilization, sulfur capture, sodium control, and ash-mineral engineering. Their effects are strongly dependent on chemical speciation, dispersion, dosage, temperature, particle size, combustion atmosphere, and system configuration. Several interventions have lowered ignition temperatures, improved boiler efficiency, and reduced NOx, SO₂, particulate matter, or PAH emissions. However, these benefits may be accompanied by increased NOx emissions, HCl formation, agglomeration, corrosion, greater water demand, or metal-leaching risks. Coal–water slurries incorporating biomass and organic waste expand opportunities for waste valorization through microexplosions, secondary atomization, and reduced activation energy, whereas biomass cofiring provides a relatively practical retrofit pathway. This review proposes a staged selection framework based on fuel and ash characterization, thermokinetic testing, pilot-scale validation, energy-specific emissions monitoring, and multicriteria assessment. The findings indicate that technological success depends on matching materials to fuel characteristics and conducting phased, long-term validation under actual power-plant operating conditions. Priority research areas include multifunctional nanocomposite catalysts, locally sourced residue-based additives, predictive atomization–ash models, and multiobjective optimization integrating efficiency, emissions, corrosion, and material circularity.]]>
