The possibility of the efficient storage of large amounts of energy and its subsequent rapid conversion into useful electromagnetic energy has been studied. Efficient and economical storage of energy is possible in the form of kinetic energy of rotation. Conversion of energy stored in this manner into electromagnetic energy has been accomplished by using the rotating mass as the armature of a series wound homopolar generator. A successful prototype generator has been built and its performance compared with the theoretical operation of such a device. The prototype generator was capable of storing 29,000 joules when operating at 20,000 rpm. When it is operated under short circuit conditions, a current pulse of 56,000 amperes maximum is obtained in the single‐turn series field coil. Liquid mercury brushes were developed especially for this generator, since very low circuit resistance is required for self‐excited operation. The starting of the flow of mercury in the brush system serves to start the generator in operation. The possible further development and uses of this generator are discussed.