Could flywheels be the future of energy storage?

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.

How much energy does a flywheel store?

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, σmax /ρ is around 600 kNm/kg for CFC, whereas for wrought flywheel steels, it is around 75 kNm/kg.

What is the core element of a flywheel?

The core element of a flywheel consists of a rotating mass, typically axisymmetric, which stores rotary kinetic energy E according to (Equation 1) E = 1 2 I ω 2 [J], where E is the stored kinetic energy, I is the flywheel moment of inertia [kgm2], and ω is the angular speed [rad/s].

How do electrical flywheels work?

Electrical flywheels are kept spinning at a desired state of charge, and a more useful measure of performance is standby power loss, as opposed to rundown time. Standby power loss can be minimized by means of a good bearing system, a low electromagnetic drag MG, and internal vacuum for low aerodynamic drag.

Are lithium-ion batteries a good choice for a flywheel?

The robust characteristics of flywheels deem them highly suitable for applications requiring fast response and high daily cycles, a need that is growing as grid inertia reduces. Lithium-ion batteries are currently the technology of choice for a fast response but suffer from limited cycle and calendar life.

Are flywheel standby losses a problem?

The issue of flywheel standby losses is often cited as a problem, but in a well-designed flywheel, for a given power, this may be no higher than the ancillary power needed for thermal management of Li-ion to maximize life.