The increasing electricity demand, propelled by economic expansion and population growth, underscores the critical need for dependable power generation. Steam power plants (SPPs) remain a cornerstone of Indonesia’s electricity production, particularly those fuelled by coal. Energy conservation in SPPs is paramount, focusing on enhancing energy efficiency. However, the current performance assessment, solely based on energy efficiency, overlooks crucial aspects of energy utilization, necessitating a combined approach integrating exergy analysis. This study aims to identify the energy and exergy efficiencies in ultra-supercritical (USC) SPPs, providing management guidelines to prioritize improvement efforts for enhancing thermodynamic efficiency in the XYZ USC SPP system. Previous research has highlighted significant exergy destruction in boilers and turbines. Hence, this study aimed to evaluate the energy and exergy analyses at 100%, 75%, and 50% loads on the XYZ USC SPPs unit. The Engineering Equation Solver software was used for the analysis. The power plant efficiencies were 46.94%, 47.01%, and 47.03% at 50%, 75%, and 100% loads. The largest exergy destruction occurred in the boiler, with 1,918 MW at 50% load, 1,609 MW at 75% load, and 1,416 MW at 100% load. The smallest exergy destruction occurred in the condensate extraction pump, with 1.441 MW at 50% load, 1.457 MW at 75% load, and 1.544 MW at 100% load. These findings from the XYZ USC SPP demonstrate that, although the plant achieves competitive energy efficiency levels, substantial opportunities remain for thermodynamic enhancement. The exergy analysis identifies the boiler as the principal source of exergy loss, largely due to inefficiencies in combustion and heat transfer processes. In addition, turbines – particularly the low-pressure turbine – also contribute to significant exergy destruction, warranting targeted optimization efforts.