The urgent imperative to curtail carbon emissions necessitates the extensive implementation of renewable technologies. However, the intermittent nature of renewables poses challenges to sustainable and efficient energy storage. This project focuses on exploring long-term energy storage systems, evaluating both their cost-effectiveness and efficiency. Utilizing the well-established concept of Power to X to Power, the project employs modeling techniques to analyze various technologies, enabling a comprehensive comparison of long-term energy storage systems based on efficiency and cost. The first candidate for energy storage is Power to Heat to Power, involving a model that calculates the cost and efficiency of a heat storage device. This model incorporates components such as a heat pump cycle and a thermal engine cycle, assessing different temperatures and technical properties. A second candidate involves storing excess electricity as hydrogen. The second model, Power to Hydrogen Tank to Power, focuses on the storage of excess electricity in the form of hydrogen. It examines the use of Solid Oxide Electrolyzer Cells (SOEC) and Solid Oxide Fuel Cells (SOFC) in both liquid and gaseous hydrogen storage systems, assessing their potential as effective energy storage technologies. The ultimate objective is to facilitate a comparative analysis of different Power to X to Power technologies in terms of efficiency and investment cost. This research contributes to understanding viable long-term energy storage solutions, informing strategic decisions for a sustainable and low-carbon future.