What is superconducting magnetic energy storage (SMES)?

Superconducting magnetic energy storage (SMES) systems store energy in the magnetic field created by the flow of direct current in a superconducting coil that has been cryogenically cooled to a temperature below its superconducting critical temperature. This use of superconducting coils to store magnetic energy was invented by M. Ferrier in 1970.

Why is superconductor material a key issue for SMEs?

The superconductor material is a key issue for SMES. Superconductor development efforts focus on increasing Jc and strain range and on reducing the wire manufacturing cost. The energy density, efficiency and the high discharge rate make SMES useful systems to incorporate into modern energy grids and green energy initiatives.

Does a superconducting coil have a maximum charging rate?

This means that there exists a maximum charging rate for the superconducting material, given that the magnitude of the magnetic field determines the flux captured by the superconducting coil. In general power systems look to maximize the current they are able to handle.

How to increase energy stored in SMEs?

Methods to increase the energy stored in SMES often resort to large-scale storage units. As with other superconducting applications, cryogenics are a necessity. A robust mechanical structure is usually required to contain the very large Lorentz forces generated by and on the magnet coils.

How does a superconductor work?

Here the energy is stored by disconnecting the coil from the larger system and then using electromagnetic induction from the magnet to induce a current in the superconducting coil. This coil then preserves the current until the coil is reconnected to the larger system, after which the coil partly or fully discharges.

Is SMEs a viable energy storage method?

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.