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So basically the reason diesel locomotives have slower acceleration is some combination of increased weight and limited on-board power supply?
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(06-15-2017, 03:29 PM)tomh009 Wrote: Diesel engine might have something like 35% efficiency.

An electric motor could be up to 90%.  A top-notch fuel cell will be 70%.  Electrolysis might be up to 60%.  But apply all three and you end up with 38%, almost the same as diesel -- and half the efficiency of a battery-operated electric vehicle.  Really not fabulous.  My rough efficiency estimates:
35% diesel (ICE loss only)
40% fuel cell (electrolyte loss + fuel cell loss + electric motor loss)
70% battery electric (battery loss + electric motor loss)
90% OCS electric (electric motor loss only)

I'm finding this whole discussion really interesting. Are there reputable detailed studies comparing these? It seems really complex to actually figure out the relative efficiencies.
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(06-16-2017, 08:04 AM)jamincan Wrote: So basically the reason diesel locomotives have slower acceleration is some combination of increased weight and limited on-board power supply?

Exactly!
For daily ion construction updates, photos and general urban rail news, follow me on twitter! @Canardiain
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(06-16-2017, 08:01 AM)danbrotherston Wrote: A perusal of wikipedia would seem to suggest one of the benefits of the overhead catenary system is actually an increase in power over what is feasible with diesel.  Also, there is substantially less weight not having to haul around a diesel engine and a generator, but that's obviously lost on dual mode trains.

And not having to haul around a full tank of diesel fuel.
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(06-16-2017, 09:26 AM)tomh009 Wrote:
(06-16-2017, 08:01 AM)danbrotherston Wrote: A perusal of wikipedia would seem to suggest one of the benefits of the overhead catenary system is actually an increase in power over what is feasible with diesel.  Also, there is substantially less weight not having to haul around a diesel engine and a generator, but that's obviously lost on dual mode trains.

And not having to haul around a full tank of diesel fuel.

That probably helps too, but I imagine not as much as not having to haul around a diesel engine.  I believe this is one reason our previous high speed train attempts were powered by gas turbine engines.
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I wonder if the 1965 blackout played a part as well - fears of your high-speed train being stranded in the middle of nowhere when the power goes out.
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(06-15-2017, 10:36 PM)jamincan Wrote: Aren't diesel locomotives actually driven by electric motors too?

“just as completely electric as though their power came from a third rail or an overhead wire”

   


If that sounds like a bit of sophistry, well, at least they had actual running trains.
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And back then it probably wasn't impossible to find early pure diesel engines still in use in yards somewhere.
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(06-16-2017, 10:07 PM)DHLawrence Wrote: And back then it probably wasn't impossible to find early pure diesel engines still in use in yards somewhere.

I don't think it's impossible now.  I'm pretty sure the UPX trains are driven by a mechanical drivetrain instead of a diesel electric one.
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One of the main downsides to a Diesel-Electric Locomotive is the Diesel Prime Mover doesn't accelerate or rev up as quickly as it would in a car or a truck, and so the power output from the generator is not as nice while it revs up as it would be in a purely electric locomotive. 

Note: the 66 GO MPI MP40-3C locomotives have an EMD 710GB 16 cylinder diesel prime mover and a Caterpillar C-27 diesel engine for the Head-End Power generator. the 1(+16 on order) GO  MPI MP54AC have 2 16-cylinder Cummins QSK60 EPA Tier 4 engines as prime movers and HEP generators.
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