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Cake day: June 22nd, 2023

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  • Leaving the train at 1/3rd the speed it decelerated from?

    What’s really happening:

    • Barcelona want to use regen braking to reduce power usage of their metro - this is good.

    • Adding batteries to store all that energy for 30seconds at each stop is impractical in some way. It makes the train too heavy / They can’t charge quick enough / The charging loss is too high. So, they go for a smaller battery.

    • The electrical grid gets the rest of the energy dumped into it, only to supply it back to the train when it accelerates again. They use the grid like a battery.

    • Some public relations person heard this and issued a press release - “Barcelona using metro as power station”.

    • Every engineer working on the project simultaneously groans in despair. The resulting low frequency wave shakes the foundations of Sagrada Família, setting the construction back another generation.