@Diogenese_Shiplap You reminded me of a fascinating flywheel powered trolley I saw in a museum somewhere: It was electrically powered, but had no batteries even though it traveled away from power lines. The trolley had a giant flywheel that the motor would spin whenever it was connect to power at stops and the trolley would then tap the flywheel to propel itself.

Looking for it on Google shows that a few other vehicles also use this idea of mechanical energy storage.

@RegalBeagle The gyroscopic spinning flywheel is/was a great idea. Early attempts showed it could work, but I think there were inertia difficulties and the idea of a heavy spinning wheel below your feet seemed cost-averse. Also there wasn't the type of low-friction bearings needed to have it all work. Then the idea got shunted aside. I still think flywheel assisted vehicles hold a lot of potential, if for nothing else just to assist two tons of metal getting from zero to 5mph. That would save a LOT in fuel costs.

@Diogenese_Shiplap Flywheel 'batteries' are still used in specific black start applications when reconnecting power plants to the grid. A flywheel can dump all of its energy in a very short time allowing them to act as giant capacitors handling the massive current spikes that come from a power plant having to suddenly start every motor currently connected to the downed grid.

Bearing technology has come a long way. Maybe it's due for a resurgence?