This study reports on the feasibility of applying polymer electrolyte membrane fuel cells (PEMFCs) system to an energy storage system (ESS). We modeled each constituting system to compute the overall efficiency of the ESS. As a result, it was verified that the power plants’ electric powering capability can be curtailed. The amount of reduction is equal to that of 2nd Gori Nuclear Power Plant currently under construction. We calculated that approximately 320.85 L/day · MW of hydrogen is produced on a national scale. Also, Seoul’s demand output power of PEMFC and the requisite area of sites to install the PEMFC system are approximately 236 MW and 59059 m² respectively. This study can contribute to preventing the upsurge of the entire electric powering installed capability. Based on the present technology level, this study diagnoses the use of hydrogen-based ESS which will be introduced in the upcoming hydrogen economy period. Considering the water electrolysis by polymer electrolyte membrane water electrolyzers are currently at the beginning of commercialization and the energy density per mass of hydrogen is exceedingly high, we anticipate that the future of hydrogen base ESS’ effectiveness will reach greater levels than the analysis of this study.

The Flywheel Energy Storage System (FESS) stores the electric energy into the rotational kinetic energy of the rotor. The FESS uses housing components so that the rotor spins inside the housing where the vacuum is maintained. Thus, the housing component is exposed to the load due to this pressure difference, and designing the housing that can efficiently support this load is crucial. Meanwhile, in the situation wherein the rotor lifting force is blocked, the rotor drops and damages the system. Thus, it is necessary to equip a structure capable of supporting the corresponding impact of the rotor drop. In this study, the design of the housing components is described by considering the structural robustness of the housing components, under the atmospheric pressure and impact of the rotor drop. For the pressure load, structural analysis was conducted following the different housing lid shapes: concave, convex, and flat. For the impact of the rotor drop, the structural analysis was conducted following the different terminal velocities of the rotating rotor. As a result, the designed housing components comprise a concave housing lid and the safety suspension 1 mm beneath the rotor. Considering the results, it operates stably under the conditions stated above.

The importance of environmentally-friendly energy production has been growing globally, and studies on energy storage technologies are underway, to supply produced energy to consumers. Flywheel Energy Storage System (FESS) is physical energy storage technology, that stores generated electric energy into kinetic energy in the rotor. To design the FESS with a high-strength steel rotor, that is inexpensive, recyclable and easy to manufacture, mechanical and electrical components such as a rotor, bearings, etc. are required. Among these, safety of rotor and bearings is critical, because the rotor with high rotating speed may cause axis failure or fracture of the rotating body. Proper size of a rotor for required energy storage and radial, axial forces generated by the spinning rotor was calculated, considering gyroscopic forces acting on the rotating body. Based on the calculation, adequately sustainable angular ball bearings were selected. As a result, by conducting structural, modal and critical speed analysis, safety verification is presented pursuant to the American Petroleum Institute (API) publication 684.