An Advanced High Efficiency Modular, Flywheel Energy Storage System

Heshmat, H. and Walton, J.F., “An Advanced High Efficiency Modular, Flywheel Energy Storage System,” Presented at The IAPG Mechanical & Electrical Systems Working Groups Meeting, Golden CO May 3-5, 2010

In the paper the author will present the design and operating test results for a novel energy storage flywheel system. Proof of concept testing of a small flywheel with motor/generator using compliant foil gas bearings to support both generator and flywheel was conducted.  Tests were completed from ambient pressures down to about 1 psia to show that flywheel energy storage systems using foil bearings are competitive with magnetic bearing based systems.   Due to the shock tolerance inherent in foil bearings the total system size and weight is less than magnetic bearing based systems which require auxiliary/catcher bearings.  Comparison of measured and predicted windage loss show that total windage losses for the foil bearing based system are less than that needed to power the magnetic bearings.  Tradeoff studies showing that power densities of 2000 W/L and Energy Densities of greater than 150 W-Hr/L are possible with the foil bearing system and high strength composite materials at practical/achievable stress levels.  The power and energy densities are not just for the flywheel but for the flywheel, generator, bearings and housing.

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