
Flywheel energy storage (FES) works by accelerating a rotor () to a very high speed and maintaining the energy in the system as . When energy is extracted from the system, the flywheel's rotational speed is reduced as a consequence of the principle of ; adding energy to the system correspondingly results in an increase in the speed of th. You can think of it as a kind of "mechanical battery," but it's storing energy in the form of movement (kinetic energy, in other words) rather than the energy stored in chemical form inside a traditional, electrical battery. [pdf]
Flywheels, one of the earliest forms of energy storage, could play a significant role in the transformation of the electrical power system into one that is fully sustainable yet low cost.
Flywheel energy storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy.
Thanks to the unique advantages such as long life cycles, high power density, minimal environmental impact, and high power quality such as fast response and voltage stability, the flywheel/kinetic energy storage system (FESS) is gaining attention recently.
Indeed, the development of high strength, low-density carbon fiber composites (CFCs) in the 1970s generated renewed interest in flywheel energy storage. Based on design strengths typically used in commercial flywheels, σ max /ρ is around 600 kNm/kg for CFC, whereas for wrought flywheel steels, it is around 75 kNm/kg.
However, the high cost of purchase and maintenance of solar batteries has been a major hindrance. Flywheel energy storage systems are suitable and economical when frequent charge and discharge cycles are required. Furthermore, flywheel batteries have high power density and a low environmental footprint.
In 2010, Beacon Power began testing of their Smart Energy 25 (Gen 4) flywheel energy storage system at a wind farm in Tehachapi, California. The system was part of a wind power/flywheel demonstration project being carried out for the California Energy Commission.

Flywheel energy storage (FES) works by accelerating a rotor () to a very high speed and maintaining the energy in the system as . When energy is extracted from the system, the flywheel's rotational speed is reduced as a consequence of the principle of ; adding energy to the system correspondingly results in an increase in the speed of th. In this paper, state-of-the-art and future opportunities for flywheel energy storage systems are reviewed. The FESS technology is an interdisciplinary, complex subject that involves electrical, mechanical, magnetic subsystems. The different choices of subsystems and their impacts on the system performance are discussed. [pdf]
Among the different mechanical energy storage systems, the flywheel energy storage system (FESS) is considered suitable for commercial applications. An FESS, shown in Figure 1, is a spinning mass, composite or steel, secured within a vessel with very low ambient pressure.
The flywheel energy storage system (FESS) is one such storage system that is gaining popularity. This is due to the increasing manufacturing capabilities and the growing variety of materials available for use in FESS construction. Better control systems are another important recent breakthrough in the development of FESS [32, 36, 37, 38].
Other opportunities are new applications in energy harvest, hybrid energy systems, and flywheel’s secondary functionality apart from energy storage. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
While many papers compare different ESS technologies, only a few research , studies design and control flywheel-based hybrid energy storage systems. Recently, Zhang et al. present a hybrid energy storage system based on compressed air energy storage and FESS.
Three common machines used in flywheel energy storage systems are the induction machine (IM), the variable reluctant machine (VRM), and the permanent magnet machine (PM). For high-power applications, an IM is utilised as it is very rugged, has high torque, and is not expensive.
Permanent-Magnet Motors for Flywheel Energy Storage Systems The permanent-magnet synchronous motor (PMSM) and the permanent-magnet brushless direct current (BLDC) motor are the two primary types of PM motors used in FESSs. PM motors boast advantages such as high efficiency, power density, compactness, and suitability for high-speed operations.

In the 1950s, flywheel-powered buses, known as , were used in () and () and there is ongoing research to make flywheel systems that are smaller, lighter, cheaper and have a greater capacity. It is hoped that flywheel systems can replace conventional chemical batteries for mobile applications, such as for electric vehicles. Proposed flywh. Automakers are beginning to install flywheel technology instead of batteries on new test electric cars. Formula 1 racing cars like Ferrari, Renault, BMW, and McLaren have completed thousands of laps using this technology. [pdf]
Electro-mechanical flywheel energy storage systems (FESS) can be used in hybrid vehicles as an alternative to chemical batteries or capacitors and have enormous development potential. In the first part of the book, the Supersystem Analysis, FESS is placed in a global context using a holistic approach.
In HEV and EV, the flywheel is used to store the energy, and used when harsh acceleration is required to climb steep uphill roads (Amiryar and Pullen, 2017; Mousavi et al., 2017). FESS rank better than batteries as they serve longer life cycles, high charge and discharge rate cycles, high power density, and higher efficiency.
Among the different mechanical energy storage systems, the flywheel energy storage system (FESS) is considered suitable for commercial applications. An FESS, shown in Figure 1, is a spinning mass, composite or steel, secured within a vessel with very low ambient pressure.
Flywheel energy storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy.
Three common machines used in flywheel energy storage systems are the induction machine (IM), the variable reluctant machine (VRM), and the permanent magnet machine (PM). For high-power applications, an IM is utilised as it is very rugged, has high torque, and is not expensive.
The flywheel energy storage system (FESS) is one such storage system that is gaining popularity. This is due to the increasing manufacturing capabilities and the growing variety of materials available for use in FESS construction. Better control systems are another important recent breakthrough in the development of FESS [32, 36, 37, 38].
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