Main disadvantages of flywheel energy storage technology

What are the advantages and disadvantages of flywheels?

They are also less potentially damaging to the environment, being largely made of inert or benign materials. Another advantage of flywheels is that by a simple measurement of the rotation speed it is possible to know the exact amount of energy stored.

Are flywheels a viable energy storage technology?

Flywheels have a relatively low energy density and are not feasible for longer term energy storage compared to other technologies. Additionally, they have a low current efficiency and high level of self-discharge due to air resistance and bearing losses (A.J. Ruddell, in Stand-Alone and Hybrid Wind Energy Systems, 2010).

What are the limitations of Flywheel design?

One of the primary limits to flywheel design is the tensile strength of the material used for the rotor. Generally speaking, the stronger the disc, the faster it may be spun, and the more energy the system can store.

Do flywheel energy storage systems need to be embedded in the ground?

Still, many customers of modern flywheel energy-storage systems prefer to have them embedded in the ground to halt any material that might escape the containment vessel. An additional limitation for some flywheel types is energy storage time. Flywheel energy storage systems using mechanical bearings can lose 20% to 50% of their energy in 2 hours.

What happens if a flywheel is over tensile strength?

When the tensile strength of a flywheel is exceeded the flywheel will shatter, releasing all of its stored energy at once; this is commonly referred to as "flywheel explosion" since wheel fragments can reach kinetic energy comparable to that of a bullet.

What are the advantages and disadvantages of flywheel accumulators?

Another advantage of flywheels is that by a simple measurement of the rotation speed it is possible to know the exact amount of energy stored. However, use of flywheel accumulators is currently hampered by the danger of explosive shattering of the massive wheel due to overload.