Abstract - This study gives a critical review of flywheel energy storage systems and their feasibility in various applications. Due to the highly interdisciplinary nature of FESSs, we survey different design. . Flywheel energy storage projects are gaining momentum as a sustainable solution for industries needing rapid energy response and high-cycle efficiency. What is L/kW in a. . From data centers needing split-second power backups to subway systems recapturing braking energy, flywheel installation is becoming the rockstar of short-term energy storage solutions. The global market is spinning up fast, projected to reach $1. 2 billion by 2028 according to recent industry. .