Energy and exergy analyses are conducted at the Dieng Geothermal Power Plant to determine the energy loss of components by calculating the efficiency, rate of change in energy flow, and exergy loss of each component. The data were collected on each component, including production wells, turbines, the main condenser, inter-condensers, and cooling towers, with the data collection occurring from April 2017 to March 2018. Energy and exergy analyses begin by calculating the enthalpy and entropy of both input and output from the compiled temperature data, with the help of a steam table. The study results show that the lowest efficiency was 67% in the turbine, and the highest energy change rate seen was 5.8×10 4 kW, in the inter-condenser. In addition, the greatest exergy loss was 50 Mw, which occurred in the turbine, indicating it was the component most in need of repair. In summary, the study results clarified that the component that needed to be treated and repaired at the Dieng Geothermal Power Plant was the turbine.