Question

A SMES (superconducting magnetic energy storage) coil is made from a toroidal ring coil (torus). The
coil’s cross-sectional radius is d = 1 m and radius of the torus is r = 1 km. The torus is wound with N =
150,000 turns and is able to carry a current I = 100,000 A. a) Calculate the magnetic flux density in the
torus. b) What is the amount of energy stored in the torus? c) If a city requires 100 MW of power how
long can this storage ring of this type power the city in case of a blackout in power generation? Assume
there are no losses in the conversion of energy from stored dc to ac energy required by standard grids.

Answer 1