This article reports the secondary energy effects (wear/erosion/abrasion, slagging, and fouling) of ash in coal on the energy performance of coal fired thermal power plants of capacity range 30-500 MW. It also gives the extent of capacity reduction in equipment due to firing of coals with higher ash contents. At an ash content of 75% in coal, the effects on the system (without fuel oil support) follow: (a) decrease in Hardgrove index from 80 to 44; (b) 20% of the specific energy consumption (SEC) of induced draft (ID) fans, 10%-12% of that of forced draft (FD) and primary air (PA) fans, 17% of that of drum mills, and 12%-13% of that of ball-race mills and bowl mills, are accounted for by wear/erosion/abrasion effects; (c) decrease of fan efficiencies by 5%-6% points due to wear/erosion/abrasion effects; (d) capacity loss originating from wear/erosion/abrasion effects alone is 8% due to ID fans, 1% due to PA fans, and 6% due to mills; (e) fouling effects are high fouling factor, decrease in boiler efficiency by 3%, and capacity reduction of 2%; and (f) CFs based on overall unit performance are 31% for units below 210 MW, 26% for 210 MW units, and 40% for 500 MW. Considering the capacity restrictions due to individual equipment, CF at an ash content of 57% is 85% due to the boiler fans, 84% due to Raymond bowl mills and drum type ball mills, 71% due to slow speed large ball and race mills, and 88% due to ash slurry pumps. When the coal exceeds 70% and tends toward 76%, the heating value of coal tends toward zero. The effects of slagging (independent of ash content in coal) area 20% decrease in boiler water wall loading, a 3.5% points decrease in boiler efficiency, and capacity reduction of 14%.