Superconductive energy storage for diurnal use by electric utilities

A summary report of a five-year study of superconductive energy storage for electric utility systems is presented, Conceptual designs over that period have all been for one layer solenoids of aluminum-NbTi composite conductors cooled to 1.8 K in superfluid helium, The solenoids are mounted underground in bedrock in one or more tunnels. The two preferred designs in 1980 are: a 15 tunnel solenoid arranged in a circular pattern and a large radius single tunnel solenoid. The electrical energy storage efficiency in all cases is 95 to 96%.