this post was submitted on 17 Sep 2023
475 points (95.2% liked)
Technology
68599 readers
3975 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related news or articles.
- Be excellent to each other!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, this includes using AI responses and summaries. To ask if your bot can be added please contact a mod.
- Check for duplicates before posting, duplicates may be removed
- Accounts 7 days and younger will have their posts automatically removed.
Approved Bots
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Guessing that replacing that with a large battery that charges at night is unreasonable due to the torque needed? You'd probably need a battery larger than a train engine to be able to even do a few stops and starts. Which is why electric trains are wired all the time.
If someone knows for sure I'm super curious!
11-minute version
3-hour version
This is exactly what I was looking for, thank you!
Is this whole thread a joke or have you people not heard of electrified rail
I mentioned it in my comment that you're replying to. "wired" could easily refer to above or below, just continuous current is what matters for this discussion. Why do ask?
Edit: Wait did you think we can electrify all rails? Outside of major cities it's a maintenance and safety nightmare, and a LOT of our freight moves via rail.
Global warming is a major maintenance and safety nightmare outside and inside major cities.
There are trains available that will run on overhead lines where available, and diesel when they're not. There's also passenger trains that have batteries as well.
It's doable, especially considering how efficient trains are.
It's kinda the default actually. Locomotives might lack pantographs if they never see electrified track but diesel locomotives aren't direct drive but diesel-electric. I'm not that deep into the topic but from what I've heard a mechanical transmission would be a nightmare.
Modern trains are almost exclusively electric final drive, off the top of my head I can't think of any exceptions. There are so many different voltages of overhead pantographs and drive motors though, there is almost always some type of converter needed to provide the right voltage to the drive motors.
Overhead wires aren't 3-phase, so convertor is required anyway.
A lot of locomotion uses DC motors, so they can run line voltage directly.
And what operational voltage of such motor?
1.5KV DC is reasonably common for commuter rail.
1.5KV doesn't sound like operating voltage of DC motor. Maybe you wanted to say BLDC instead?
You can electrify your rail because that's what we did.
No. Also outside of city cost of electrification is much cheaper.
Same for me
Not sure where you're from but if you pretend it's Switzerland then this comment is for you https://reddit.com/r/trains/s/UE3DSOPUdf
Not Switzerland, Russia
Trains are already pulling what 100 cars. It's easy enough to have a car that's a battery. But I think overhead lines are the way to go on the vast majority of lines.
The problem with battery trains is that locomotives hardly sit around long enough to charge unless it's some sort of switcher or in for maintenance. Really the only use case for battery locomotives outside of switchers is passenger service where it's fairly common for a train to sit for eight plus hours. Amtrak and Siemens are actually doing this with 15 of the new airo trainsets which will run on the empire line. The trainsets will specifically run on battery while within the new York city tunnels where diesel locomotives are only allowed to operate under emergency.
There is probably a use for train with battery on partially electrified lines.
The train charge on the electrified part and use batteries on the rest.
https://www.mobility.siemens.com/global/en/portfolio/rail/rolling-stock/commuter-and-regional-trains/alternative-drives.html
It's definitely a thing already.
For transport of people, it seems germany has some train with battery. They replace their hydrogen trains.
Supercapacitors.
If I ran the local power grid I'm not sure I'd want cargo trains using line power for traction, unless there was some mandated weight or length limit 🤔
Without some cargo limit I think sections of the line's voltage will just collapse under the current being drawn, whenever the cargo train moves off from a complete stop - especially if it's a multi mile long cargo train that seems common in the US
The Kiruna - Narvik electrified line is operating just fine with LKAB running the heaviest trains in Europe with a mass of 8600 tonnes.
90% off the cargo trains are powered with electricity in France and can reach up to 750m.
I agree It's not multi mile long but it's totally possible to have electric cargo trains.
There's little chance of that happening, but even if there was, they'd just use batteries for the acceleration phase. That's what hydrogen fuel cell trains do anyway, because the fuel cell can't produce enough power on it's own to accelerate the train from a stop, so they're used to charge batteries that allow it to do so.
The reason why there's little chance of that happening is there are already very many cargo trains powered by overhead lines. We've been doing it for 150 years and in continental Europe there are many sections of track that are entirely electrified because it made more economic sense than running a wasteful (compared to a steam power plant) diesel generator to power the already electric engines of the trains.
I really can't see a train pulling so much that it crashes the entire system. *When you think about it it's one (moderate size) generators worth.
I think this guy never learned about resistance. Maybe he skipped physics classes, maybe he didn't even have them yet.
Would you ellaborate on what you mean, and the assumptions you drew from the quoted text?