Flywheel energy storage systems: A critical review on technologies, applications, and future prospects

Energy storage systems (ESSs) are the technologies that have driven our society to an extent where the management of the electrical network is easily feasible. The balance in supply-demand, stability, voltage and frequency lag control, and improvement in power quality are the significant attributes that fascinate the world toward the ESS technology. However, being one of the oldest ESS, the flywheel ESS (FESS) has acquired the tendency to raise itself among others being eco-friendly and storing energy up to megajoule (MJ). Along with these, FESS also surpasses the quality of high power density, longer life cycle, higher rate of charge and discharge cycle, and greater efficiency. In this article, an overview of the FESS has been discussed concerning its background theory, structure with its associated components, characteristics, applications, cost model, control approach, stability enhancement, maintenance, and future trends. The FESS structure is described in detail, along with its major components and their different types. Further, its characteristics that help in improving the electrical network are explained. The applications of the FESS have also been illustrated through their economically available prototypes. The economics associated with FESS technology has been projected. A thorough survey of various control strategies of FESS highlighting the merits and demerits of each has been discussed in depth. The stability enhancement and maintenance of the FESS unit have also been enumerated. Further, the article also recommends numerous future work that plays a vital role in the hassle-free operation of FESS for the efficient functioning of the electrical power system.