A superconductive magnetic energy storage system has been designed to smooth the pulsating power requirement of the Fermilab accelerator. The system stores 1 MWh and operates at peak power level of 200 MW on a 10 sec cycle. The magnetic system employs cryogenically stable superconductors and a flux-forcing normal secondary. The power system uses phase controlled thyristor rectifier-inverters similar to those employed in the main accelerator power supply.