Operational planning is the process of planning and organizing the resources to achieve organization's strategic plan. Planning the supply chain, maintenance, marketing, and production operations are the main parts of operational planning. The operational planning for energy investments is crucial since these investments are costly and the efficiency of the investments necessitates an ample planning process. Also, the type of energy source changes the operational planning need. Understanding these needs and the research gaps can enhance the efficiency of the energy systems. The objective of this chapter is to reveal the primary needs and research focuses on operation planning in energy systems. A comprehensive literature review is conducted to identify the research focuses and the gaps in operational planning in energy systems.