34,000-Ton ‘Infinity Train’ Will Recharge Itself with Gravity

The secret to this train's seeming ability to violate the laws of thermodynamics is that it carries a really heavy load downhill, then goes back uphill empty to pick up a new heavy load.

Regenerative breaking on the downslope wouldn't be able to provide enough charge to get the full train back to the top, but it is plenty to get the empty train back to the top.

Really cool use of the technology, not a perpetual-motion machine (it will run out of charge after carrying the last load down the hill, since it will no longer have extra mass to harvest potential energy from).

Some time ago, Tom Scott did a video about an old quarry gondola system that accomplished this without batteries (where the heavy gondolas coming down provided the driving force for the system), and no power was required except briefly to start it up again after a stop.