I mean it is clickbait but it is also a thing that can easily work and there are already mining trucks that do this.

They work because they transport matter from a higher place to a lower place and therefore are much heavier downhill then uphill.

Electric trains and trams in Europe already have regen braking. And no need for batteries!

Yeah, but that does require a fair bit of additional infrastructure, running overhead wires and having it connected to the power grid. Makes sense in populated areas, but for mining trains in Australia, potentially 1000s of kms from the nearest city? This seems like a reasonable alternative

How does that work without batteries? Where does the energy go?

Back into the power grid.

Quote: When regenerative braking is employed, the current in the electric motors is reversed, slowing down the train. At the same time, the electro motors generate electricity to be returned to the power distribution system

https://www.ctc-n.org/technologies/regenerative-braking-trai...

I assume it goes into the grid. Possibly to other trains that need the power right then.

The light rail MAX trains in Portland use regen braking without batteries, as one train is slowing it's generating power for other trains that are in motion[1].

1: https://www.wired.com/2013/06/portland-light-rail/

This could be such a cool detail for post-apocalyptic SF story where someone drives old electric mining truck up the mountain to load up useless rocks to charge the truck on the way down and provide a little bit of electricity for their little community of survivalists.

You should write it! :)

It’s not perpetual motion, it’s just moving things downhill with extra steps.

The extra steps are useful for sure. Storing the generated energy in batteries works on a route where the net cargo movement is downhill even if there are some uphill sections along the way.

They're gaining energy by taking bits of the hill down the hill.

Of course it's not really a perpetual machine. It only works as long as there is enough material to transport downhill.

That's not what is happening here. It uses gravity to generate energy as the mass going downhill is significantly greater than the mass going back up. The mass of the load is used for "powering" the regenerative braking system (resistance is converted to electricity, stored in the batteries) when going downhill. The batteries are now charged when at the bottom. The heavy load is removed from the train. The generated power is used to take the train with significantly less mass back up to be refilled. There is no "perpetual" energy here. Basically the fuel is the load. It still takes energy to load and unload the payload. No magic here. It's just a function of how much mass can the train take downhill, how much regeneration occurs during that operation, and how much energy it takes to take the empty train back up to the top.

Just as you can take a tiny regenerative toy car, give it a few little revving pushes on the floor (let's say 4 feet of regeneration), you can let it go and have it go 100 feet, as all that mass you used from your arm to charge the battery was transferred (obviously not 100%) to the battery. It's not perpetual motion. It's just converting mass into energy. Pure physics here.

This is the same concept when using water, rocks, sand etc. and gravity for batteries. It's just a simple transfer of potential energy.

Understand, I was thinking it will only work in narrow applications like removing mountain of rocks. Plus saying infinity implies some sort of unity

A normal truck uses it's brakes constantly when going down hill, turning all that potential energy of the cargo into heat. This truck charges batteries to slow itself down via a generator. At the bottom, it weighs much less, thus even accounting for loses, there's enough energy to get the "lightweight" truck back to the top.