[Don Plumley]

Flywheel Energy Storage - idea that you power a large flywheel with grid (solar/wind) power during the day, then during sags, at night, etc., the flywheel delivers power to the grid by running the motor in reverse (that's a generator). The flywheel spins really, really fast - like 20K RPM. I'm familiar with a project that uses superconducting magnetic bearings to reduce rotational losses in the storage system and enable rpm's not really feasible with mechanical bearings.