Battery-electric "Infinity Train" will charge itself using gravity | Hacker News Reader

Battery-electric "Infinity Train" will charge itself using gravity

newatlas.com

52 pointscroes59 comments

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)

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.

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.

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.

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?

The bigger issue is size. A train can brake at each car, not just the locamotive. So that means hundreds of regenerating electric motors spread across the train. Dump that all to a collective "third rail" and all manner of electrical havoc will begin as out-of-phaze motors start driving each other to do the wrong thing.

I don't see how that makes sense.

Instead of a freight train lets consider the slightly aged (god I'm old) electric train I would once have caught when I worked in London. As you say, each set of wheels can be braked independently and they're all using regenerative electric motors, so that's maybe 40 wheel sets on the train I'm thinking of. But, traction current is supplied at only a maximum of four points on that train, I'd guess only one is actually ever in use for simplicity.

So instead of "electrical havoc" it's a pretty simple local problem for the engineers designing the train.

For freight trains the power is applied at the locomotive only. However for passenger trains it is very common for each car to have drive wheels. This allows for more acceleration and thus more traction. There is no technical reason you can't do this for a freight train, but it is some engineering work that isn't normally done. It is a little tricky for this application because typically ore is loaded through the top of the car and unloaded underneath which makes finding a place to get the power to the motors tricky, and dust from loading/unloading can wreck things - these are solvable problems but still problems.

Conventional freight wagons are unpowered yes, but I don't see how that's relevant to this claim that somehow if you have multiple electric motors you can't dump power into the traction feed when decelerating. British passenger trains do this today, it's not even a quirk, it's the default. The local train operator boasts that they dump 78,700,000 kWh per year from deceleration back into the traction feed. [No I don't know why they picked those units]

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.

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), …

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.

My thoughts exactly, it sounds like marketing bullshit but no, it could actually work well if they get out as much inefficiency as possible

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).

https://electrek.co/2024/02/05/hitachi-abb-complete-fully-el...

Possibly. I feel like I saw something much longer ago. Might have been this one: https://www.popularmechanics.com/technology/infrastructure/a...

I was able to find that they were probably Hitachi trucks, but could not find the source we are likely thinking of.

Fortescue has been testing a mine truck capable of that for a year or two (it was built with liebherr).

They use to do this with mining carts. "One" goes down the hill full while pulling the empty "one" back up.

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.

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?

https://www.youtube.com/watch?v=VVaWmEI9O1w

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.)

Well inner mine transport can be net positive as well with electrical mining trucks. Then you need the energy for explosives and stone cutting, which needs further investigation, whether this can be offset by the energy gained of the stones travelling downhill. Water should be better used for hydroelectrical production.

> Water should be better used for hydroelectrical production.

Well, putting water on a downhill train _is_ hydroelectrical production. Just a very cumbersome way.

The stone could be called lithoelectrical production.

There are a couple of good undergraduate physics final problems buried in here.

There's that one train line carrying ore from Northern Sweden down to the Norwegian coast that is net-positive in energy-generation.

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.

https://youtu.be/cIQ0yIZgQeE?feature=shared

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.

The things people will do to avoid putting up catenaries truly are wild.

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)

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!

143 km is very short for an Australian rail line. If you said it would cross all of Australia, then I'd believe you :)

How come Soviets electrified all rail? It wasn't because they're swimming in money...

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.

Electrified rail is not magic, you still need an engine on at least 1 car. You still need some way of converting electrical current to a force to push you down the tracks.

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.

No, but they were swimming in cheap labour.

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.

The economic liberalisation was a response to the decline. They didn't stray away from more 'proper' communism because everything was hunky dory, you know.

Statistics about the Soviet economy are notoriously hard to make sense of. First, they ran a rather weird economic system (compared to the west), and second, you can't necessarily trust the statistics, there weren't really any independent organisations at all like we have in democracies. No independent media to check, no independent statistical institutes etc.

Even in the west environmentalism was only just getting en vogue in the second half of the 20th century. But the Soviet Union takes the cake in terms of how much environmental damage they were willing to take for a bit of extra economic output.

Also, if your mine is done, you can load up your trains and bring them to the next up to the mountain mine! Lifetime of the catenaries might be a lot longer than the mine.

Comparing modern day Russia to the Soviet Union is not realistic.

Well, they did not. Only major lines are electrified

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.

Is the track already there - you can't build tracks for that price.

Naturally. Building an electrified track from scratch is much more expensive.

For very good reasons.

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

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.

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.

What if the train need to go uphill loaded and downhill empty?

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.

Or you keep a diesel generator on the locomotive itself, making it a sort of hybrid.

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.

Diesel-electric drivetrains are not "hybrids" in the sense that they have an energy storage device. The same type of drivetrain was used in submarines and tanks during WWII, no one calls those a hybrid.

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.

As a strict matter, this is non-renewable energy.

An elevator with more steps. Still cool.

This is old news in Scandinavia.

svk.se (Swedish grid operator) is listing current statistics for energy production and has the category 'Not Specified':

> Unspecified production includes, for example, gas power, wave power and braking power. Production from plants with more than one production type and where these can not be separated is also included in this category.

Braking power refers to regenerative braking, energy that's put back on the grid from the electric trains. Presumably from the iron ore trains from up north.

Unfortunately it does not list exactly how much of the 'Not Specified' is from braking power alone. Generation in this category as we speak is 589 MW.

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