In the age when energy storage technology is under constant innovation, the flywheel energy storage gradually enters people's line of sight as a highly promising new form of energy storage method, which fascinates its unique charm and broad application prospect. In such an ingenious design, electrical energy converted to kinetic energy is further converted back into electrical energy when needed and used directly or after conversion as an innovative solution for energy storage and utilization problems.

 

The principle of flywheel energy storage is seemingly simple but embodies profound scientific wisdom. Speaking simply, a wheel rotates at a high velocity, storing the electricity, then releasing it as needed. In fact, that is a course of mutual transformation between kinetic energy and electrical energy. It generates mechanical energy by silently converting electrical energy and stores it, while the electric motor drives the flywheel to rotate at high speed during the charging phase. The process is exactly reversed in the case of discharging. Now, the high-speed rotating flywheel acts like a "power source" and drives the generator to generate electricity, re-converting the stored mechanical energy into electrical energy for release. Otherwise put, when we have excess energy, we keep the wheel at a very fast rotation, and where we will require energy, we stop the power feeding; through inertia, it keeps on moving, to carry along at a very fast rotation the attached generator, which will provide us with our required electricity. Unlike traditional battery energy storage, the flywheel energy storage does not directly store electricity inside the wheel; instead, it ingeniously converts it into kinetic energy.

 

Although this method has some limitations in the aspect of energy storage capacity, its unique "secret weapon" is the extremely high instantaneous power, which has made it extremely effective in large power consumption cases that need to be achieved within a short period of time. To reduce the energy loss in the process of storage, some advanced technical measures are adopted in series in modern flywheel energy storage systems. The huge rotating flywheel fixed on the stator with magnetic levitation high-speed bearings could rotate at high speed in an almost frictionless environment. Some even work in a vacuum environment to further reduce frictional resistance and keep efficiency high. With this, for higher energy storage, the flywheel needs to rotate at an even higher speed. But with increased rotation speed, new problems arise: the flywheel must support much bigger centrifugal forces. The requirement of the performance of the flywheel material will be very high. Low-speed flywheels are normally made of steel, and high-speed ones are made from carbon fiber composite material, with high tensile strength hence storing more energy at high rotational speed. As compared to battery storage, a form of chemical storage, there is a number of important advantages offered by flywheel energy storage: High energy density-in the same volume or weight, a flywheel will be able to store more energy.

 

In the same way, flywheel energy storage boasts long service life and low cost, allowing it to operate through many charge-discharge cycles with no significant deterioration in performance. Besides, it can provide instantaneous high-power discharging in a few seconds or even less, which is a characteristic particularly important in many applications with extremely high power requirements. The FES system uses fully suspended rotation by maintenance-free magnetic bearings to greatly reduce mechanical components in wear and almost free from the maintenance and upkeep of mechanical bearings. It could lower the usage cost and reduce the difficulty of maintenance. The advantages in these aspects make flywheel energy storage widely used in many areas. In electromagnetic catapult technology for aircraft carriers, FES would, hence, be indispensable. Launching the aircraft at very high speeds requires huge currents to be released in electromagnetic catapults instantaneously and, in turn, very high instantaneous energy output capability.

 

The flywheel energy storage system can provide huge amounts of energy in a short period of time, meeting the needs of electromagnetic catapults and providing a strong guarantee for the combat capabilities of aircraft carriers.

 

In the field of racing cars, the application of flywheel systems has also brought more powerful performance to racing cars. In a nutshell, it is at the moment when these cars need to accelerate that the flywheel systems, fitted onto the racing cars, will enable huge currents; thus, faster acceleration and improving the performance as well as making the cars competitive. Moreover, applying flywheel energy storage in power has great value. It is applied for the purpose of supplying power in emergency situations. At moments of various faults or emergencies within the electrical network, it provides stability and timely feeding for the flawless and safe operation of the entire electrical grid. Because of their specific advantages, flywheel energy storage is used widely in the aerospace and laser industries. In space operation, it is highly demanded to have super reliable energy storage and supply equipment on the spaceship.

 

High energy density and long life determine that the flywheel energy storage would be a perfect fit. In the laser field, some high-power laser devices require support in terms of instantaneous high-power energy, which could be provided by the flywheel energy storage, and provide powerful support for laser technology development. It is sure that in the near future, when the technology advances, more fields would be applying and promoting the technology of flywheel energy storage. It will bring great changes to energy storage and utilization and therefore be able to make an important contribution to solving the energy crisis and the realization of sustainable development. We have every reason to believe that, on the future energy stage, flywheel energy storage will be of utmost importance and become one of the key forces driving energy technology progress.

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• Flywheel Energy Storage