Comments on: Vycon Plans to Tap Speeding Subway Trains for Immense Amounts of Kinetic Energy

By: _sam_

_sam_ — Mon, 05 Sep 2011 13:24:17 +0000

@RichardNeill
Re gravity braking – this is true (though I’m not sure it’s implemented on all lines) and I have a feeling they also have that on the Paris Metro and other systems.

But in addition, according to a quick Google, it appears that tube trains manufactured since 1992 do also in fact have regenerative braking.

I’m sure this is true for most other systems using rolling stock less than 20 years old, so it kind of seems like this is a non-product (‘Our incredible new product allows you to do something you’ve been doing for the past 20 years!’), unless there is some genuine benefit over current regenerative braking systems.

(And btw – not an expert on the details but yes I think they do put the power back directly on the third rail where another train can use it, rather than needing to use batteries. So it should be pretty efficient.)

By: Quinny

Quinny — Mon, 05 Sep 2011 12:15:22 +0000

Why not just give the trains regenerative braking and a small battery to put this power into? (or even have them put it back into the grid via the 3rd rail, but this could be more complex…)

You’d need to put power back in to the train again when it is going to accelerate anyway, why not store the power on board?

By: RichardNeill

RichardNeill — Sun, 04 Sep 2011 23:21:40 +0000

The London Underground has had a “regenerative braking” system ever since it was built by the Victorians 100+ years ago. Rather than use electrical storage, it uses gravity: the tracks slope downwards away from stations, and then upwards as the train decelerates into the station!

By: msyin

msyin — Sat, 03 Sep 2011 20:35:59 +0000

The best thing would be to try it out on a shuttle train in NYC and do some real world research after they work out the technical details as to how to install the system and send the energy back into the third rail. This sites shows that there is more than just one way to create, use and store energy so I would love to see the very busy mega cities like NYC try something that would help their systems.

By: alexgh

alexgh — Sat, 03 Sep 2011 04:41:16 +0000

@Ennet the flywheel isn’t located on the train itself. It’s meant to store the energy when the train decelerates and the flywheel then outputs the stored energy when the train leaves.

By: Ennet

Ennet — Fri, 02 Sep 2011 15:14:42 +0000

I’ve just read two articles on “tapping power” from highways or trains as if that could magically be used to power something else (like a city). During acceleration and cruise the train (or car) will use power and there is no way you can extract any amount of power without having to input even more power (since nothing is 100% efficient).

Regenerative systems can only be used when the train (or car) is braking; instead of turing kinetic energy into heat (through mechanical brakes) you can use it to spin up a fly wheel or generate electric power. That will reduce the total energy consumption but in the end the train (or car) will always _consume_ energy.

A flywheel may be useful in a car where it is difficult to handle the massive amounts of energy that is generated when braking. However, for trains, it doesn’t make sense; it’s much simpler to use the electric motors as generators when breaking and simply feed the power back into the power grid. This is already quite common, at least in European trains and subways.

By: charli

charli — Fri, 02 Sep 2011 03:52:35 +0000

This is a great idea, I don’t know why they haven’t done this sooner. That said, 90% efficiency seems a bit optimistic for a system like this. Also, the trains use a lot more energy thAn a prius. This site’s journalism seems to be degenerating quickly. First the vacant greenwashing, then bias moved in, and now grammatical errors are rearing their ugly heads…