Superconducting Magnetic Energy Storage

Superconducting Magnetic Energy storage (SMES)

Superconducting magnetic energy storage (SMES) systems store energy in a magnetic field.
This magnetic field is generated by a DC current traveling through a superconducting coil. In a normal wire, as electric current passes through the wire, some energy is lost as heat due to electric resistance.
However, in a SMES system, the wire is made from a superconducting material that has been cryogenically cooled below its critical temperature.
As a result, electric current can pass through the wire with almost no resistance, allowing energy to be stored in a SMES system for a longer period of time. Common superconducting materials include mercury, vanadium, and niobium-titanium.
The energy stored in an SMES system is discharged by connecting an AC power convertor to the conductive coil
SMES systems are an extremely efficient storage technology, but they have very low energy densities and are still far from being economically viable.

Advantages over other energy storage methods

There are several reasons for using superconducting magnetic energy storage instead of other energy storage methods.
The most important advantage of SMES is that the time delay during charge and discharge is quite short.
Power is available almost instantaneously and very high power output can be provided for a brief period of time.
Other energy storage methods, such as pumped hydro or compressed air, have a substantial time delay associated with the energy conversion of stored mechanical energy back into electricity.
Thus if demand is immediate, SMES is a viable option. Another advantage is that the loss of power is less than other storage methods because electric currents encounter almost no resistance.
Additionally the main parts in a SMES are motionless, which results in high reliability.