Barcelona is turning subway trains into power stations

jeffw@lemmy.world to Technology@lemmy.world – 160 points –
Barcelona is turning subway trains into power stations
grist.org
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Are they generating more power than they are spending by making the train go? Has Barcelona mastered perpetual motion??

It's good thing, sure, but it's no savior. The blurb makes it sound like it's a net gain of energy, and that's impossible. It's not free energy. It's just upcycled waste.

I don't read it as magical energy created out of nothing, but I do read it as "free" energy that would exist whether this regeneration system is used or not, that would otherwise be lost as heat.

With or without regenerative braking, the train system is still going to accelerate stopped trains up to operational speed, then slow them down to a stop, at regular intervals throughout the whole train system. Tapping into that existing energy is basically free energy at that point.

Only because of the speed of the train. Fuel spent accelerating to later brake is wasted fuel. More efficient would be spending only enough fuel to come to a full stop without braking.

So you want the trains to coast from station to station? Do you really believe that or is it very important for you to be right?

Efficient from an electrical standpoint, but not a transportation one. You can't "improve" it so much that it no longer does the thing it's supposed to do.

It reduces waste, yes.

Sure, and that's not a bad thing. But what is revolutionary and newsworthy about what Barcelona is doing?

Did you click on the article? It’s made very clear very early in the article that they have added regenerative braking systems to the trains. This is well established technology. It’s in every Prius since 1997 so I would think you wouldn’t be confused about whether this is perpetual motion or if they are making grand claims of net energy surplus. It doesn’t say any of that. It’s cool that they are applying the technology in this way. Why does this seem confusing to you?

Because it sounds like somebody just found out about the technology and decided to make an article about it like it's some sort of new and novel thing, when it's really not.

I think you’re projecting those expectations onto it. I’m totally fine to hear that a notable city has successfully implemented a cool technology even if it’s not some world first for science, and I don’t think the headline overhypes this for what it is.

The revolution is that they are doing something that has existed since the early 1900s... But it's in Barcelona so it's chic.

It's cool and all that, and likely just a side effects of the new trains having that.

It's also the default for commuter trains, they pretty much all do it.