Rapid industrialization and the increased use of consumer electronic goods have increased the demand for energy. To meet the increasing energy demand, global nations are looking for energy from renewable sources rather than non-renewable sources, to adhere with the sustainability principle. As energy from renewable sources is still in the experimental stage, there is a need to use available energy sources optimally. Considering this, the present study aims to identify, evaluate, and reveal the interrelationship among critical challenge factors in improving the heat rate performance of coal-fired thermal power plants. The study identifies twenty critical challenges through a comprehensive literature review. Then, to evaluate the identified critical challenges, the grey-DEMATEL (Decision Making Trial and Evaluation Laboratory) technique is used. For evaluating the challenges, this study conducts an empirical analysis in a thermal power plant in India. The findings reveal that air preheater leakage, coal flow balancing, and air heater air outlet temperature are the top three critical challenges hampering the thermal power plant’s performance. Additionally, fourteen challenges come under the cause group, while eight challenges come under the effect group. The findings of the study can assist industrial managers in overcoming problems in their thermal power plants. The results can also guide the development of a robust and reliable framework for mitigating these challenges.