Battery-electric "Infinity Train" will charge itself using gravity
65 comments
·June 22, 2025Cthulhu_
I started reading this with cynicism because lololol magic electricity from nothing, but no, if it goes down while full and up while empty it could work. And of course they can hook up a diesel engine if it doesn't properly work.
ryao
I had the same thought, only to read the detail about the train being empty on the return trip, which would make this feasible.
If they devise a grid tie system using a third rail to receive/transmit power, they could avoid placing a battery on the train and excess energy could be provided to the grid, which would be even more cost effective. Even if they opt out of connecting to the grid, the battery could be located at a stationary location rather than carried by the train, which should reduce the train’s permanent mass, lowering the size of the battery needed.
pjc50
High-power grid connections are surprisingly expensive. I would expect that it's been done this way because it's now the cheapest non-diesel option.
algo_trader
This isnt HVDC..
Industrial locomotives are ~10MW and 12kV or similar. So the entire ..err ..drive train is probably $10M? And the regen is free? But you have to step-up and -down to the battery?
Maybe a more informed reader can.. ahem... step in and inform us?
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shiandow
It's a system that's already been proven to work.
Though I'm not sure if any others used a battery. In a simple mechanical version you just connect two carts to each other so one is pulled up while the other goes down.
masklinn
Yes there are multiple systems in testing or production which do battery KERS e.g. Fortescue‘s roadrunner mine truck. There are also trains which do energy recovery but shove it onto the network e.g. Sweden’s Malmbanan.
As you note direct gravity devices are centuries old: water balances, gravity balances, paired boat lifts (like the Falkirk wheel), …
nullsmack
I've read about this same thing happening with electric dump trucks. There's articles from 2019 about one: https://www.greencarreports.com/news/1124478_world-s-largest...
There are more articles about it, but this is one that didn't need a login to read.
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voidUpdate
My thoughts exactly, it sounds like marketing bullshit but no, it could actually work well if they get out as much inefficiency as possible
anon12315
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goodcanadian
I am too lazy to find a source, but I saw a similar thing a few years ago with an electric mining truck (recover enough energy going downhill loaded to go back uphill unloaded).
wumms
goodcanadian
Possibly. I feel like I saw something much longer ago. Might have been this one: https://www.popularmechanics.com/technology/infrastructure/a...
6510
They use to do this with mining carts. "One" goes down the hill full while pulling the empty "one" back up.
AngryData
Norway I believe it was has also had energy positive mining trains for awhile as they mine up in the mountains, load it up, and bring it down to the coast using electric generators for brakes.
looofooo0
I wonder that in certain parts of the world, the train network could become net positive electrical contributor by mining stones in quarries up the mountain?
eru
Depends on what you measure, I guess? Ie I don't think you have enough excess energy to pay for the actual quarrying itself. (Though you might be able to become energy positive if you take water as a ballast, not stone. Water is easier to pump into some tanks.)
drob518
There are a couple of good undergraduate physics final problems buried in here.
ginko
There's that one train line carrying ore from Northern Sweden down to the Norwegian coast that is net-positive in energy-generation.
sandworm101
Fyi, virtually all diesel locamotives already employ regenerative braking. They just send the electricity to resistors, turning it into heat. The amount of energy is simply staggering. No battery tech can absorb the power fast enough. Its funny that this train is in australia. Only on a very flat run will braking be so slow that power can be stored efficiently.
sidewndr46
If it's just being dumped into a resistor bank that isn't really regenerative. I guess if you used it for cabin heat or something that'd be useful however.
occz
The things people will do to avoid putting up catenaries truly are wild.
lukan
Because it is a huge investment, that also has maintainance costs.
This train on the other hand seems superior in every way for this specific use case (getting ore from high altitude to low altidude and empty trains back up)
unwind
It's Australia, the rail line is 143 km (89 miles). Putting up poles and hanging catenaries over that kind of distance is probably not cheap?
Either way it sounds brilliant, both simpler and better than catenaries, I like it!
kzrdude
143 km is very short for an Australian rail line. If you said it would cross all of Australia, then I'd believe you :)
brnt
How come Soviets electrified all rail? It wasn't because they're swimming in money...
toast0
They probably weren't sending loaded trains only downhill and only sending unloaded trains uphill.
They also didn't have the same kind of battery capacity as we have today.
Electrified rail avoids shipping the engine and the fuel with the load, which ia often a big win in efficiency.
vkou
Because prior to them, Russia was a backwater with anemic infrastructure, and they started massive greenfield infrastructure projects at a time that the technology was mature.
lukan
No, but they were swimming in cheap labour.
Cthulhu_
A quick google says they hauled about 60% of their cargo with electric locomotives, 70% of passenger traffic. Currently about 51.5% of modern-day Russia's 105.000 km rail network is electrified. Compare with others on this chart (which seems to omit Russia for some reason): https://www.itf-oecd.org/transport-connectivity-trends-compa.... TL;DR, they did not, in fact, electrify all rail.
As for your swimming in money comment, I'm not sure what you mean; the Soviet Union was an industrial powerhouse and the second largest economy in the world between WW2 and the mid-80's, its economic decline only started after that with economic liberalisation under Gorbachev, followed by both oil price collapse and the costliest disaster in human history (until then), the Chernobyl incident, both in '86. Japan overtook it as the 2nd largest economy only by 1990.
omgtehlion
Well, they did not. Only major lines are electrified
Tade0
The project's cost is estimated to be $50mln, with the battery itself most likely being at most $10mln from that.
That $50mln would maybe be enough to electrify a single, 40km track.
goodpoint
For very good reasons.
wumms
Article is the announcement from 2022, now they unveiled the prototype: https://electrek.co/2025/06/21/fortescue-infinity-train-elec...
Posted 3 days ago (12 points, 1 comment): https://news.ycombinator.com/item?id=44339903
twobitshifter
Usually mines end up deep underground and require a lot of energy to get the materials to the surface and loaded on to the train. However once you’ve achieved that it is possible to just let gravity carry you back to sea level.
bluGill
Partially true. Mines tend to be underground, but often they are in mountains or other high ground and so the ore overall is moving downhill.
samrus
What if the train need to go uphill loaded and downhill empty?
pjc50
I suspect there's a maintenance depot somewhere near the bottom station, which is likely to have a charger. It's just that's not the routine use case.
drob518
Or you keep a diesel generator on the locomotive itself, making it a sort of hybrid.
atomic_cowprod
Diesel locomotives are already hybrids (pretty much all diesels built since the mid-20th century are diesel-electric). I imagine that a generator large enough to charge up a locomotive would add too much extra weight to the design, however I could see a modified diesel locomotive being utilized to both push a dead electric train and to at least partially recharge that train's batteries during the journey.
pmontra
You keep a diesel locomotive at hand. They probably need one to move along the track to do repairs. Not sure if it's got enough HPs to move ore back, but anyway, why should they want to put ore back into the mine? Sending equipment yes, but it's probably light enough to travel on the return train.
rich_sasha
As a strict matter, this is non-renewable energy.
A clearer title for this would be:
Battery-electric "Infinity Train" will charge itself using potential energy.
(Potential energy being stored in the position of the mined ore)