might be useful for those "flywheel" based energy storage devices. https://en.wikipedia.org/wiki/Flywheel_energy_storage https://en.wikipedia.org/wiki/Flywheel

might be useful for those "flywheel" based energy storage devices. https://en.wikipedia.org/wiki/Flywheel_energy_storage https://en.wikipedia.org/wiki/Flywheel_energy_storage (My favorite part of the article where it talks about trying to use in vehicles...)