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Comment by LikeBeans | Hacker News Reader

I just watched a YouTube video of a battery powered train in the UK [1]. If longevity and number of cycles is much higher than lithium ion coupled with a safer profile then I think this would be an ideal application for sodium ion. Really cool.

Edit: I'm talking about for both onboard batteries (for the safety profile) and the BESS container mentioned in the video. Not to mention trains wouldn't have to compete with the lithium ion battery supply that is taken over by EV cars and trucks.

[1] https://youtu.be/sARTvQj5jIg

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Aren’t trains the perfect use case for a direct connection to the electric grid?

I'm very much rooting for this. A lot of train tracks are not electrified simply because it is not economical to do so. I know that most of Denmark(outside of greater Copenhagen, and Aarhus) is still operating Diesel trains. Such battery backed "electric" trains may be just the thing to turn those Diesel trains into cleaner ones without needing a huge capital investment of electrifying vast track networks that are not used justifiably as much.

New battery powered trains unfortunately are even more expensive of a capital investment. Especially when it comes to maintenance over classic electric trains.

What I always found weird is that a power rail system isn't used. One could do it even without a third rail...

How can it be done without a 3rd rail?

I can imagine running electric wires along tha tracks is a big challenge. However I think using the container BESS mentioned in the video above receiving trickle charge from the grid would leave opportunities for local solar generation to augment the grid too. Think of it like a decentralized solution. Scales much more and provides resilience against outages.

Wiring up the tracks shouldn't be expensive. See there's two metal tracks, just use one for the positive line and one for the negative line. ;)

Well, the tracks are normally gapped, they still need to be adapted to be high current continuous.

It significantly increases the cost of track per mile. The (then) Soviets started electrifying their railways in 1930, and didn't finish until 2002.

(strictly technically speaking not direct to grid but yes)

The problem is gaps in electrification. So you might have electrified two parts, but with a big gap without wires

This lets the train cross those (and mind you this would have to be something a larger gap, if it's a smaller gap without stops, let's say 1km, then the train just doesn't care)

Normal electric trains already carry batteries for this reason, and to be able to manuever off the track in case of a power outage. Much like trams.

There's a big difference however between a train with a short term battery backup and one that rides on pure battery power for an extended range.

Deutsche Bahn has been running battery-powered trains on some rural German lines that have yet to be electrified for a while now.

I rode in this as a railfanning child while on a day trip somewhere in the Siegerland. Looong ago. 1978/79 maybe? So exiting, because having never seen them before :)

https://de.wikipedia.org/wiki/DB-Baureihe_ETA_176

Much, much later somewhere in the 'Ruhrpott', around 199x, feeling rather surreal because of switching back and forth slowly through the apocalyptic yards of abandoned industrial ruins, with brand new Nokia regional HQ in the midst. Shiny new glass buildings with multiple large satellite dishes on the roof. And a soon to be opened S-Bahn track to there.

https://de.wikipedia.org/wiki/DB-Baureihe_ETA_150

Oh, imagine frieght trains that carry a few battery coaches, and periodically stop at charging stations in the middle of nowhere and then continue on their journey without polluting and being a menace to the urban grids.. Now, if only such battery systems could come down in cost so much that it becomes a no-brainer.

> urban grids..

There are regions where the grid and the plants powering that are separate from the maingrid. (West-)Germany was like that, still is. For historical reasons, like different frequency of 16 2/3Hz. It's called 'Bahnstrom'.

https://de.wikipedia.org/wiki/Bahnstrom

Same applies to Austria and the Swiss. (D-A-CH)

https://de.wikipedia.org/wiki/Liste_von_Bahnstromanlagen_in_...

The former (East-)Germany did it different, while needing the same frequency.

They used something like this, decentrally https://de.wikipedia.org/wiki/Bahnstrom#/media/Datei:DR_Umfo... to convert from the 50Hz maingrid to 16 2/3Hz, where they had no coverage from the 'Bahnstrom-'grid.

If your'e wondering wtf!? 16 2/3Hz at all, that was because at the time of early electrification with AC (less transmission loss over longer distances), that frequency produced less sparks/arcing with the then available electro-motors for that single phase of AC, RPM, lack of advanced (mobile(power))electronics, and so on. Legacy...

DC had different trade-offs.

Since you wrote freight-trains, which isn't light-rail, which also had its own power-plants and grids, and mostly still has?

There is also class 777 electric-battery hybrid.

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