Value stream mapping (VSM) is powerful and effective to map out processes and to eliminate critical issues. This paper describes the application of VSM to reduce energy loss in a power plant. In doing so, three stages of the proposed VSM were used, namely (1) mapping the big picture and the process flow, (2) identifying the potential energy loss, and (3) analyzing and determining the future state. At the first stage, using observations and interviews, the big picture and the process flow was mapped out to understand the main suppliers and customers, as well as the main process in the power plant. At the second stage, energy loss equations and heat energy rate analysis were used to identify and analyze the potential energy losses. At the final stage, the analysis identified the top three energy loss stages in the unloading process, the top two energy loss stages in the loading process, and the top five energy loss stages in the electricity generation process. The implication of this study is outlined in the conclusion to improve VSM in the future.