The overall performance of a hydrogen storage system can be affected by various parameters, such as operation and design parameters, but also by the state of the hydrogen contained inside the storage tanks. In this work, a methodology is developed to evaluate the state of the hydrogen during the filling process and its impact on the overall system performance under variable operation conditions and design parameters. To approach as close as possible hydrogen as real gas, the thermodynamic properties of it are obtained from experimental thermodynamic tables. Based on those thermodynamic tables, a discrete database for each thermodynamic property is constructed. To minimize the error and achieve acceptable execution time, a searching method based on curve fitting techniques is developed to derive the thermodynamic properties from the discretized data. The evaluation of the hydrogen state is done based on a developed method that derives the pressure and temperature based on calculated thermodynamic properties during the filling process. The interaction between the contained hydrogen and tank during the filling process is taken into account during the methodology development. Furthermore, energy requirements for the compression system of the hydrogen storage system, including the cooling demand, are also included in the methodology. Based on the developed methodology, a transient model that can evaluate the hydrogen state condition, storage tank wall temperature condition, and energy requirement of the storage system is developed. Validation against experimental and simulation results for an actual filling event of a hydrogen storage tank is done, showing good agreement in the results. The model was used to simulate the performance of a hydrogen storage system, inspired in terms of layout by a real-world HRS storage system. The results showed that the total amount of filled hydrogen and the filling duration of the charging process are greatly affected by the compression and heat transfer phenomena occurring inside the tank. The storage tanks with lower volumes and higher operation pressure tend to be more affected by compression and heat transfer phenomena. Operation parameters such as inlet mass flow and inlet temperature, can have an impact on the system, both in terms of energy consumption and filling performance. Furthermore, based on the investigation of compression stages, the results showed that the number of stages can affect the compression ratio of each stage, resulting in lower or higher efficiency, which directly affects the energy consumption of the compression system. A parametric investigation of the upper operation pressures of the hydrogen tanks showed that the total amount of stored hydrogen is affected when the respective upper pressures vary. Last, it was shown that there is an optimal upper pressure level for each bank that can result in lower specific compression energy, indicating that the model could be used for optimization purposes.

Wind resources are highly intermittent and fluctuant, making wind turbines less reliable and the unstable power output will affect grid stability and security. This paper presents an idea of integrating the solar PV plant and energy storage system into an existing wind project, project Rödene in Gothenburg. The hybrid renewable system, which consists of two or more renewable energy sources, is considered the renewable energy development trend. An economic analysis of a 1.2 MW PV plant, 5 MW lithium-ion battery storage system and 300 kg hydrogen fuel cell storge system are assessed in terms of LCOE and LCOS of plants. The revenue stream is discussed separately, consisting of electricity tariff, ancillary services and energy arbitrage. The results show that both PV plant and energy store systems are unprofitable. When the PV panel cost is reduced more than 30% and the annual production increases at least 30%, the LCOE of the PV plant arrives at the break-even point. Also result shows the hydrogen fuel cell energy storage system is too expensive of commercial use, and the battery energy storage system has a high potential of profitable if the ancillary service in Sweden is well organized in the future