Well, this certainly feels like a better idea than a hydrogen train, for keeping service electrified when there's no power lines installed in a certain part of a route...

greencarcongress.com/2018/09/2

@bhtooefr

viewliner II, but better trucks and it's just packed full of batteires and there's a cable fed into a special port on the back of an ACS64.

Mostly /s.

@bhtooefr

Hey I figured out a worse idea:

A-B-A and A-B-B formations of battery-electric hybrid locomotives meant for medium-long distance passenger service, where some number of small diesels can turn on and off for generating electricity.

Perhaps based on the Charger or F125 body/control etc but with batteries and a smaller diesel.

@bhtooefr

new, even worse idea:

viewliner II body with lowered internal roofline so you can put small diesels on top and just lift/slide them out and replace them quickly and maintain them outside of the locomotive. (also: get the locomotive back on the road quicker.)

@coryw @bhtooefr yeah, three locomotives on a passenger train is an idea that is really hard to beat with something worse

(horrible ratio between powered-unpowered axles, say goodbye to all possible gains from recuperation, to begin with)

@pony @coryw I can do worse than that...

Rack railway with an overrun clutch.

No regeneration possible.

@pony @bhtooefr

three units isn't completely unheard of here, although I don't think it's *very* common, just because in the US at least with what we have now, two units (one of which is diverting much of its electricity generation to HEP) is "Good Enough"

Unless you mean that locomotive-hauled trains are less good, which I can't specifically speak to.

@coryw @bhtooefr for a battery powered train, they would certainly be a horrible choice with all that dead weight and everything.

@pony @bhtooefr

Aha, yeah I don't know. I presume a diesel-battery locomotive would downsize the diesel part a lot and mostly be a giant battery pack, but I don't know if that would really "work" especially for an actual train.

Norfolk Southern in the US has a handful of battery electric shunting locomotives.

Here, the thing that gets used to bridge gaps in electric service is the Bombardier ALP45DP, which is a full diesel/electric dual mode. (or GE P32AC-DM in some locations)

@coryw @bhtooefr I guess a big deal would be to get enough out of that batteries at once to get some acceleration

@coryw @pony I was under the impression that the GE ES44AC Hybrid prototype was basically intended for the same workloads as a normal ES44AC, it would just store dynamic braking energy in the battery instead of dumping it into resistors when possible, and then use that energy to reduce engine power demand for a given notch (so if there was something in the battery, notch 8 might run the engine as if it was in notch 7 or so)?

@bhtooefr @pony

I appear to have seen this before, and then forgot. I wonder where it went, they appear to have decided not to bother actually doing it.

@coryw @pony AFAICT they basically decided that it would cost too much for the fuel economy benefit.

(Freight locos aren't doing a stop-and-go cycle anyway, and diesels are already thermally efficient over a wide range of power settings, so the hybrid benefits are minimized.)

@bhtooefr @pony

railwaygazette.com/news/single

claims up to around 10% (probably "in specific situations) but there's also the fact that the E*T*44{AC|C4} might be that much more efficient on its own.

@coryw @pony Oh, additional 2000 hp. So they did it the other way - added the power on top, rather than reducing engine power when the battery was supplying power.

They were probably experimenting with how to map the power delivery, too, then, especially to make power more consistent when in a multiple locomotive consist. May have even been manual hybrid deployment, for that matter.

@bhtooefr @pony

I would think the primary application might have been "getting the train started".

@coryw @pony Yeah, although a skilled engineer may want to save some power for climbing a hill. (Conversely, you may want to throttle back on the engine and throttle up on the battery to drain the battery before a stop or a descent.)

@bhtooefr @coryw then i guess it'd be pretty interesting to learn about these batteries, because i doubt they are much like any other solution

@pony @coryw AFAIK they were using molten sodium batteries, which were a buzzword ~10 years ago - pretty high energy density for reasonable cost, but with a requirement to keep things quite hot (making them not great for most vehicle applications due to the energy requirements there, but locomotives get worked hard, so it was fine for them).

Nowadays, though, Li-ion makes more sense, due to the economies of scale involved.

@bhtooefr @coryw but can Li-ion cope with the required output/input? Light multiple unit or a shunter (or a bus?) doesn't need much, but a big mainline loco?

@pony @coryw In a hybrid application, you don't have to handle the whole power input or output.

When power is needed, the engine and the battery are two power sources that are blended together and sent to the traction motors.

During braking, the battery and the dynamic braking resistor grid become two power sinks - hit the battery with what it can take, and send the rest elsewhere.

@pony @coryw Obviously if you downsize the engine you're demanding more from the battery to get the same power, but AFAIK, the ES44AC explicitly ran a full-size, full-power engine.

So, if they did it the way I expect they did it, "notch 8" no longer means "give me everything the engine can" (which is 3280 kW), it means "give me 3280 kW, starting with the battery, and use the engine for whatever the battery can't give".

@bhtooefr @coryw 3280 kW is honestly pretty weak for a 6-axle machine :) (ok, well, i'm biased living in the world of electricity)
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