Optimization of Flywheel Energy Density Utilizing a Composite Hub

The proposal objective is to develop a flywheel energy storage system capable of achieving its maximum theoretical specific energy density, while being capable of repeated high peak-power demands. The key to achieving this objective is the development of a composite hub capable of supporting an optimized high-speed composite rim. A flywheel offers significant advantages for short duration peak loads, multiple cycles, deep discharges and rapid recharges. Under these conditions, the batteries energy/weight ratio will be significantly less, possibly less than half of the 130 watt-hr/kg, where as the flywheel's energy to weight capacity would remain constant under these same conditions. Initial calculations indicate the maximum theoretical specific energy density that the proposed flywheel could obtain is approximately 110 watt-h/kg using a high modulus carbon fiber for the composite rim in conjunction with a composite hub instead of our standard commercial grade carbon fiber rim and metallic hub currently design, which is purely cost driven.