3 ms·

> Well, for example transformers are ~98% efficient, AC lines lose around 7% per 1000 km. So with three transformers between you and the power plant and a ~300

> Well, for example transformers are ~98% efficient, AC lines lose around 7% per 1000 km. So with three transformers between you and the power plant and a ~300 km distance, you lose around 8% between the power plant and you. That's not how it works because it's assuming a point to point connection for your use case. In reality there is the grid, and from everything I know transmission losses from whichever source to your socket over that grid average out to 50% best case, to about only one third reaching the destination. The latter for instance for electrified rail.

jhgb 4y ago
Can me give you an example of such cases? Because where I live, the grid absolutely does not suffer such horrible losses. "50% best case" would be absolutely unthinkable here -- especially for purpose-built medium-voltage systems like electrical rail.
- LargoLasskhyfv 4y ago
  Since this isn't my area of expertise, no, I didn't bookmark them. Just looked into it repeatedly since the beginning of our transformation to renewable and sustainable energy here, since about 2008. I thought the same regarding losses and grid, but it seems like it is so with current technology. I live (mostly) in Germany. But as I've said, when you zoom out and look into it, considering all that goes through and into it, it seems like it. No matter where. ISTR tidbits from documentaries, many websites specializing in analysis, even wikipedia. Especially that rail thing, only one third from power plant reaching the locomotive is normal. Let's put it this way: You have a model for your use case, a (mind) map. But the map is not the territory :-)
  - jhgb 4y ago
    > Especially that rail thing, only one third from power plant reaching the locomotive is normal. Link please. Because that would be a terrible performance figure for a high power system like that. Worst possible loss figures I've been able to find for our grid are 15% losses between the power plant and the plug, and that's including the losses in low-voltage distribution (400 V 50 Hz three-phase). Modern rail runs at 25 kV/50 Hz single-phase. 66% losses would be mind-boggling. As per [1], the expected losses for powering 25 kV rail are around 7% including conversion between transmission lines and the traction lines. So even including losses between the power plant and the conversion substation, they should definitely be significantly below 20%. [1] https://vts.cd.cz/documents/168518/195369/3201.pdf/9a95e429-60d6-4903-ba9d-164e4245ee2d https://vts.cd.cz/documents/168518/195369/3201.pdf/9a95e429-...
    - LargoLasskhyfv 4y ago
      > Link please... Mission impossible for now, because sleep is long overdue. Anyway, something anecdotical: At the times, when I looked into it about 2008, I discussed that with some people, some of them 'engineers', as in the people who actually drive the trains (both freight and passenger). They also confirmed that, they even learn that during training. Can 15kV at 16 2/3Hz produce such differences? Whatever, as I said before, it isn't limited to rail, grids as they are now aren't as efficient as the models suggest. But I can't re-research this at the moment. I just know I didn't hallucinate that stuff, OK?

jhgb 4y ago

Can me give you an example of such cases? Because where I live, the grid absolutely does not suffer such horrible losses. "50% best case" would be absolutely unthinkable here -- especially for purpose-built medium-voltage systems like electrical rail.

LargoLasskhyfv 4y ago
Since this isn't my area of expertise, no, I didn't bookmark them. Just looked into it repeatedly since the beginning of our transformation to renewable and sustainable energy here, since about 2008. I thought the same regarding losses and grid, but it seems like it is so with current technology. I live (mostly) in Germany. But as I've said, when you zoom out and look into it, considering all that goes through and into it, it seems like it. No matter where. ISTR tidbits from documentaries, many websites specializing in analysis, even wikipedia. Especially that rail thing, only one third from power plant reaching the locomotive is normal. Let's put it this way: You have a model for your use case, a (mind) map. But the map is not the territory :-)
- jhgb 4y ago
  > Especially that rail thing, only one third from power plant reaching the locomotive is normal. Link please. Because that would be a terrible performance figure for a high power system like that. Worst possible loss figures I've been able to find for our grid are 15% losses between the power plant and the plug, and that's including the losses in low-voltage distribution (400 V 50 Hz three-phase). Modern rail runs at 25 kV/50 Hz single-phase. 66% losses would be mind-boggling. As per [1], the expected losses for powering 25 kV rail are around 7% including conversion between transmission lines and the traction lines. So even including losses between the power plant and the conversion substation, they should definitely be significantly below 20%. [1] https://vts.cd.cz/documents/168518/195369/3201.pdf/9a95e429-60d6-4903-ba9d-164e4245ee2d https://vts.cd.cz/documents/168518/195369/3201.pdf/9a95e429-...
  - LargoLasskhyfv 4y ago
    > Link please... Mission impossible for now, because sleep is long overdue. Anyway, something anecdotical: At the times, when I looked into it about 2008, I discussed that with some people, some of them 'engineers', as in the people who actually drive the trains (both freight and passenger). They also confirmed that, they even learn that during training. Can 15kV at 16 2/3Hz produce such differences? Whatever, as I said before, it isn't limited to rail, grids as they are now aren't as efficient as the models suggest. But I can't re-research this at the moment. I just know I didn't hallucinate that stuff, OK?