Anonymous asked in Cars & TransportationRail · 1 decade ago

Why aren't locomotives used as a source of power for utility grids?

Watching the History Channel program on freight trains, I got to wondering why these trains could not also be supplying power to the grid?

I know from when I live in San Fransisco that you can supply power from overhead lines to electric trolleys and the like, but what about the reverse?

When a locomotive is going downhill, they use dynamic braking to control the speed resulting in using the brakes less. Dynamic braking is where the electric traction motors are switched from using power to producing power, thus creating drag. The power produced is transferred to coils on top of the locomotive and expelled as heat into the atmosphere.

Why not find a way to recover that power and put it into the power grid, rather than just dumping more heat into the atmosphere?

11 Answers

  • Anonymous
    1 decade ago
    Favorite Answer

    Excellent question and there is no acceptable reason for it not happening. There is nothign new in what you are suggesting, it can and has been done, the technology has been in place for almost a hundred years.

    In some limited areas it is still done but for the most part you are absolutely correct, the excess electricity generated by regenerative braking systems (dynamic braking) is completely wasted as heat dissipated through braking grids.

    The Milwaukee Road lines west had hundreds of miles of electrified lines in Montana, Idaho and Washington from the early 1900s through 1975.

    When a locomotive was placed in regeneration the braking effort generated electricity that was returned through the overhead lines, every 30 miles or so there was a substation to keep the power at the proper voltage.

    It was not returned to the power grid but used within the system so in effect a train going downhill would supply power for a train coming uphill.

    It was an outstanding system and nothing since has come even close to matching it for efficiency.

    Envinronmental concerns or laws did not play a part in it's origin or demise, it was all financial although as the world moves toward a more environmental awareness that is what will bring back such a system.

    edit for jc: I had heard about the environmental reason but I have never seen anything that backed this up, what I have seen is the Rockefellers and other huge busnissmen had money in Anaconda Copper company, and the Milwuakee, and in General Electric, so it was natural, they built a dam at Thompson Falls, Montana, sold themselves the copper, the electricity, the locomotives and made $$$ hand over fist, just on construction.

    If you think about it, there were parallel railroads that did not convert to electricity, it couldnt have been mandated or required, it was strictly business, very good business.

    Source(s): Milwaukee employee and engineer, Montana division, 1972 through 1980.
  • 1 decade ago

    Freight locomotives CAN drive the power grid. A standard EMD traction alternator is 10-pole, which means spinning the engine at 720RPM would give 60 Hz AC and that's well within the capacity of the engine (though not its full power.) It's also 3-phase, which is exactly what you want when making multi-megawatt connections to the power grid.

    Recovering dynamic braking. BART trains currently regenerate onto the third rail and the energy feeds other trains (if there are other trains to feed.) However BART substations are not currently equipped to take surplus energy and invert it back onto the power grid. That would involve converting DC to three-phase AC, which was impractical at the time BART was built, and still quite expensive when the Pittsburg and Dublin extensions were planned. You might see them retrofit it in the future, but it boils down to cost. Will the upgrade pay for itself in spinning the electric meter backward?

    Recovering to the power grid. The big big win is if you can get large freight railroads to regenerate, such as those that go over Donner Pass or the Cascades. Trick is how do you get the power from the locomotive to the power grid? The obvious way is by (re) electrifying the railroads. Have the locomotives regenerate onto the wire. Mainline electrification will be single-phase AC, while the grid is three-phase, so you'd have to convert.

    The heat lost into the atmosphere is not a significant factor in global warming. The problem is the CO2 from the burning of fuel, which is believed to cause the sun to put much, much more heat into the atmosphere.

  • 1 decade ago

    As a matter of fact, diesel-electric locomotives have been used as emergency sources of electrical power during the Ice Storm of 1998 in Canada:

    Of course it's probably more efficient to generate electrical power at an electrical station because they can do it in bulk.

    As far as recovering the dissipated energy from dynamic braking goes, GE is currently working on hybrid locomotives which can store the recovered energy in batteries. Rail Power Technologies already have done that on a smaller scale with their GG20 Green Goat switcher locomotives IIRC.

    Hope this helps!

  • 1 decade ago

    Many 100%-electric locomotives in the world return current into catenaries for other trains when braking, slowing or running downhill.

    During Montreal's ice storm about 10 years ago, a diesel locomotive was used as "portable power plant" to supply a school or community center used as an emergency shelter. They even drove the locomotive off-track on road pavement to bring it closer to the shelter!!!

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  • Andy
    Lv 6
    1 decade ago

    It just so happens that they are working on something to use that excess power. I recently had a unit called an Evolution Hybrid in my train.It was a G.E. Evolution series locomotive.Under the catwalks was a series of Sodium Chloride(salt) batteries that are re-charged when the locomotive is in dynamic then uses that energy to help power the traction motors under power.The unit was numbered the 2010 which is when they are supposed to go into service on mainline freight trains.A unit is already in use in yard service that uses similar technology here on the UP.The G.E. techs riding with me said it will save thousands of gallons of fuel a year.The thing i found interesting was the type of batteries being used.I asked the techs why they didn't use Lithium and he said they were too dangerous in the event of a short.The Sodium Chloride batteries if shorted basically turned into a block of salt! As a humorous note a few years back we had a couple of engines that went to Mexico and didn't come back.They went looking for them and found them being used to power a town in Mexico

    Source(s): UPRR engineer for 31 years
  • 1 decade ago

    good point.

    pure electric engines have done this before on the "Milwaukee Road" (Chicago, Milwaukee, St. Paul and Pacific Railroad) on the two western divisions were they electrified (it's not anymore). the eclectic engines were highly Superior to stem and Diesel weren't out yet. they were forced because o laws against steam because of forest fires so had to go to steam powered by gas or electric. dams in the north west were opened and power was cheep. and electric started and willie on these steep mountain passes they made power thew going downhill fed back into the system so at the end of the day they would Break even. you don't get much power out of it.

    I'm watching that too. they need a Passenger train tho.

    Rango knows because he was there how cool. but that's what the tape I watched said no coal engines was a law. it's a tape it can be wrong they made it up. he was there man

    Source(s): some Milwaukee Road tape I looked at
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    6 years ago

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  • Derail
    Lv 7
    1 decade ago

    The small town I live in (1,600 people) does have a 1959 -16 cylinder -Model 648 -1,750 horsepower locomotive engine housed in a building. And it is to power the whole - or a portion - of the town during power failures. In the remote area where I live, that happens 3 or 4 times a year.

  • 1 decade ago

    The dynamic-braking isn't efficient to return power to the grid, BUT diesel prime-movers ARE just giant moving generators.

    What I'd really like to see, is taking those old US nuclear submarines sitting up at Mare Island (or where ever they are), and hooking THEM up to the grid. MUCH cleaner than diesel.

    Source(s): Ex US Navy...
  • 1 decade ago

    I know of an engine that was stolen from a US railroad that gets trains from Mexico and used for electricity. (I won't say from which railroad or where it was stolen). It was stolen from the Mexico side, (they use the US companies units to put trains together and them drag them across the bridge), and put on some long abandoned spur track out of sight. They had all kinds of wires and cables hooked up to it to electrify buildings and shanties. I guess people resort to all kinds of things when their government is corrupt and won't help it's own people.

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