FLYWHEEL, FLYWHEEL DESIGNING METHOD, AND FLYWHEEL POWER STORAGE SYSTEM

The present invention provides a flywheel having a high energy density, a designing method which facilitates the designing of the flywheel, and an energy storage system which can achieve both an increase in storage energy and a reduction in weight by adopting the flywheel. A flywheel A includes: a low-density disk having a low average density; and a high-density outer edge section which is provided on the outer circumference of the low-density disk , and has an average density higher than that of the low-density disk