The Johns Hopkins University Applied Physics Laboratory is engaged in the development of energy resources, energy utilization concepts, and energy storage methods. This Quarterly Report, summarizing work completed on the various tasks as of 31 March 1978, contains comments on limited tasks, short descriptions of meetings, trips, presentations, and other limited tasks of note performed in connection with major program tasks and articles that describe these program tasks briefly, summarize the progress made to date, and indicate future efforts to be made. The major tasks fall into the following categories: Geothermal Energy Development Planning, which concentrates on the survey of potential geothermal resources and the development of scenarios for possible exploitation and utilization in DOE/DGE Region 5, which includes all the United States east of the Rocky Mountains, excluding Texas and Louisiana; Applications Study of DOE/DGE Region 5, which concerns a study of geothermal energy applications in DOE-selected areas of the Atlantic Coastal Plain; the Low-Head Hydroelectric Program; the Community Annual Storage Energy System (CASES) and the status of a development and demonstration plan for a low-cost flywheel; and multiple-objective modeling of power plant locations.