Abstract: A modular superconducting energy storage device includes a plurality of superconducting magnet modules joined in series in axial alignment. Each module comprises a core member having a superconducting coil member wound around it and a tensioning member that retains tension in the superconductor. The ends of the superconducting magnet are adapted for connection to a current source or to the free ends of the superconducting cable of an adjacent module as required. Each module is adapted for attachment to an adjacent module for retension in axial alignment. The attachment of additional modules increases energy storage capacity accordingly.