- cross-posted to:
- news@beehaw.org
- cross-posted to:
- news@beehaw.org
You must log in or # to comment.
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?
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.
Regenerative braking on commuter trains is nothing new, it’s been around for decades.
Agreed, but here it is done highly effective. The 1.8 degree temperature difference is a huge plus too - they can now also save serious amounts of power on ventilation.
TfL, you listening?The heat on the underground is mad, makes it so hard to dress for the weather. Go out in a coat because it’s cold then get down on the central line and everyone is sweating hard
The warming is global, tubes included.
Agreed. I think TfL actually has begun looking into it but it’ll probably take years before the temperature is going to drop.
Victoria, Circle, District, Hammersmith and City, Metropolitan and the new Piccadilly Line trains (due soon) all have regenerative braking. The rest will follow as new trains are procured.
As anyone who travels on the Victoria line in the summer will tell you: it helps, but not much.
And even in some prototype bus, the Gyrobus, in the 50’s that used an electrically charged flywheel that was also (to some degree) regeneratively recharged when breaking:
Rather than carrying an internal combustion engine or batteries, or connecting to overhead powerlines, a gyrobus carries a large flywheel that is spun at up to 3,000 RPM by a “squirrel cage” motor.[1] Power for charging the flywheel was sourced by means of three booms mounted on the vehicle’s roof, which contacted charging points located as required or where appropriate (at passenger stops en route, or at terminals, for instance). To obtain tractive power, capacitors would excite the flywheel’s charging motor so that it became a generator, in this way transforming the energy stored in the flywheel back into electricity. Vehicle braking was electric, and some of the energy was recycled back into the flywheel, thereby extending its range.
Source: Wikipedia: Gyrobus
That’s incredible.
Nice, it’s probably the ancestor of the TOSA which is the same thing without the flywheel, and also from Switzerland.
It is, though, as the name of the community implies, “technology.”
Why can’t they use the excess energy to make the train go again?
They do… 1/3rd of it is used that way.
Leaving the train at 1/3rd the speed it decelerated from?
What’s really happening:
-
Barcelona want to use regen braking to reduce power usage of their metro - this is good.
-
Adding batteries to store all that energy for 30seconds at each stop is impractical in some way. It makes the train too heavy / They can’t charge quick enough / The charging loss is too high. So, they go for a smaller battery.
-
The electrical grid gets the rest of the energy dumped into it, only to supply it back to the train when it accelerates again. They use the grid like a battery.
-
Some public relations person heard this and issued a press release - “Barcelona using metro as power station”.
-
Every engineer working on the project simultaneously groans in despair. The resulting low frequency wave shakes the foundations of Sagrada Família, setting the construction back another generation.
The resulting low frequency wave shakes the foundations of Sagrada Família, setting the construction back another generation.
Ay, ¡qué lástima!
I’m still not paying a full ticket, I’ll wait until I can see a whole basilica.
Every engineer working on the project simultaneously groans in despair. The resulting low frequency wave shakes the foundations of Sagrada Família, setting the construction back another generation.
Are we sure the Sagrada Familia isn’t a source of perpetual energy?
If they ever finish SF it will kind of feel wrong.
But I guess there have been generation projects in the past. They Pyramids, etc.
We just finally get to see what one feels like.
-
