4 ms·

I had the same thought, only to read the detail about the train being empty on the return trip, which would make this feasible. If they devise a grid tie syste

by ryao 1y ago

I had the same thought, only to read the detail about the train being empty on the return trip, which would make this feasible. If they devise a grid tie system using a third rail to receive/transmit power, they could avoid placing a battery on the train and excess energy could be provided to the grid, which would be even more cost effective. Even if they opt out of connecting to the grid, the battery could be located at a stationary location rather than carried by the train, which should reduce the train’s permanent mass, lowering the size of the battery needed.

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pjc50 1y ago
High-power grid connections are surprisingly expensive. I would expect that it's been done this way because it's now the cheapest non-diesel option.
- algo_trader 1y ago
  This isnt HVDC.. Industrial locomotives are ~10MW and 12kV or similar. So the entire ..err ..drive train is probably $10M? And the regen is free? But you have to step-up and -down to the battery? Maybe a more informed reader can.. ahem... step in and inform us?
  - sandworm101 1y ago
    The bigger issue is size. A train can brake at each car, not just the locamotive. So that means hundreds of regenerating electric motors spread across the train. Dump that all to a collective "third rail" and all manner of electrical havoc will begin as out-of-phaze motors start driving each other to do the wrong thing.
    - tialaramex 1y ago
      I don't see how that makes sense. Instead of a freight train lets consider the slightly aged (god I'm old) electric train I would once have caught when I worked in London. As you say, each set of wheels can be braked independently and they're all using regenerative electric motors, so that's maybe 40 wheel sets on the train I'm thinking of. But, traction current is supplied at only a maximum of four points on that train, I'd guess only one is actually ever in use for simplicity. So instead of "electrical havoc" it's a pretty simple local problem for the engineers designing the train.
      - bluGill 1y ago
        For freight trains the power is applied at the locomotive only. However for passenger trains it is very common for each car to have drive wheels. This allows for more acceleration and thus more traction. There is no technical reason you can't do this for a freight train, but it is some engineering work that isn't normally done. It is a little tricky for this application because typically ore is loaded through the top of the car and unloaded underneath which makes finding a place to get the power to the motors tricky, and dust from loading/unloading can wreck things - these are solvable problems but still problems.
        tialaramex 1y ago
        Conventional freight wagons are unpowered yes, but I don't see how that's relevant to this claim that somehow if you have multiple electric motors you can't dump power into the traction feed when decelerating. British passenger trains do this today, it's not even a quirk, it's the default. The local train operator boasts that they dump 78,700,000 kWh per year from deceleration back into the traction feed. [No I don't know why they picked those units]

by ryao 1y ago

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pjc50 1y ago

High-power grid connections are surprisingly expensive. I would expect that it's been done this way because it's now the cheapest non-diesel option.

algo_trader 1y ago
This isnt HVDC.. Industrial locomotives are ~10MW and 12kV or similar. So the entire ..err ..drive train is probably $10M? And the regen is free? But you have to step-up and -down to the battery? Maybe a more informed reader can.. ahem... step in and inform us?
- sandworm101 1y ago
  The bigger issue is size. A train can brake at each car, not just the locamotive. So that means hundreds of regenerating electric motors spread across the train. Dump that all to a collective "third rail" and all manner of electrical havoc will begin as out-of-phaze motors start driving each other to do the wrong thing.
  - tialaramex 1y ago
    I don't see how that makes sense. Instead of a freight train lets consider the slightly aged (god I'm old) electric train I would once have caught when I worked in London. As you say, each set of wheels can be braked independently and they're all using regenerative electric motors, so that's maybe 40 wheel sets on the train I'm thinking of. But, traction current is supplied at only a maximum of four points on that train, I'd guess only one is actually ever in use for simplicity. So instead of "electrical havoc" it's a pretty simple local problem for the engineers designing the train.
    - bluGill 1y ago
      For freight trains the power is applied at the locomotive only. However for passenger trains it is very common for each car to have drive wheels. This allows for more acceleration and thus more traction. There is no technical reason you can't do this for a freight train, but it is some engineering work that isn't normally done. It is a little tricky for this application because typically ore is loaded through the top of the car and unloaded underneath which makes finding a place to get the power to the motors tricky, and dust from loading/unloading can wreck things - these are solvable problems but still problems.
      - tialaramex 1y ago
        Conventional freight wagons are unpowered yes, but I don't see how that's relevant to this claim that somehow if you have multiple electric motors you can't dump power into the traction feed when decelerating. British passenger trains do this today, it's not even a quirk, it's the default. The local train operator boasts that they dump 78,700,000 kWh per year from deceleration back into the traction feed. [No I don't know why they picked those units]