Flywheels have been a method of power storage for thousands of years; the idea of using a spinning object to store and provide power is nothing new. However, during the twentieth century, the flywheel fell out of use with the improvement of batteries. The physics that made it work initially also made it appear less convenient.
Those physics are complex, but some simple concepts can be used to explain them. Perhaps the best-known flywheel is the simple children’s spinning top. These hold power from the first spin, then that power maintains the spin until, eventually, it is used up by friction from the surface it is spinning on and resistance from the air.
However, changes in design can make a great difference. A more powerful initial spin, for example, will keep the top spinning longer. Using a different top that is heavier or bigger will also produce a longer spin. And spinning on a smooth, hard surface is much more effective than using an uneven floor. The same principles are being applied to transform flywheels into viable and competitive energy storage systems.
When used as long-duration kinetic energy storage, the objective is to maximize the power the flywheel holds, the length over which it can discharge, and efficiency. Flywheels can operate at speeds of more than 9,000 rpm. The flywheels will be housed in vacuum containment to minimize air resistance and are supported by magnetic bearings to further minimize friction. The result is a product that can charge quickly, typically reaching full speed in minutes, quicker than other energy storage options.
Amber Kinetics is the pioneer and industry leader of long-duration kinetic energy storage and has installed flywheels across the globe. The company’s flagship product, the M32, offers an insight into how flywheels look and work in operation. Each unit houses a flywheel which is installed below ground level. A single unit has a power capacity of 8kW with a discharge duration of four hours.
The result is a scalable system that is highly responsive to energy demands. Amber Kinetics has successfully deployed and installed units in Australia, China, Japan, Philippines, and the US. However, the benefits of their flywheels for energy storage systems are not just about the power stored and discharged. The flywheels are designed and manufactured to provide a cleaner energy storage solution than others in the market. With its recyclable steel design, the process for producing flywheels does not require mining for its materials nor any hazardous or chemical materials.
Renewable energy is an essential part of the fight against climate change. While batteries helped pave the way for the integration of renewables, there is an emerging need for technologies which will enable a truly clean energy future. With advancements in flywheel technology, there is a newfound opportunity for us to harness that future.