Abstract: A device for the accumulation of elastic energy and converting it into electrical energy, which provides the highest possible efficiency of energy storage and conversion. The device uses a high load capacity and efficiency of the roller screw mechanism and the ability of disc springs to store and release energy with the greatest possible specific elastic deformation. The device is equipped with a brake, which makes it possible to maintain the accumulation of elastic energy for a long time. In the state of energy storage, the motor-generator works as a motor, and to convert the stored elastic energy into electrical energy, it works as a generator.