Hacker News new | past | comments | ask | show | jobs | submit login

> Spread across the entire Tube system, that technology would result in savings of £6m, about $9m.

Ok, but my understanding is that doing anything across the entire tube system' would no doubt cost trillions. Repainting all the guard rails would probably cost more than 6mil. So the proposition won't save a dime. It might be environmentally friendly and might be a good idea for new stations/trains, but the money would be better spent on other projects.

In short: Does spending a million on this regenerative breaking produce more electricity than installing a million's worth of solar panels on the roof? Which saves the most carbon per pound spent?




Presumably you would only add this to the train cars not the track. Also electric motors can generally also act as generators so the additional costs on new cars would probably be minimal.

PS: Cars only weigh 85,000 lb or so which means you only need to store something like 10kwh depending on top speed.


I'm only going from the OP. The savings they describe seem minimal (6mil) whereas they are dealing with a notoriously expensive tube system. Carbon savings are great, but one should always ask if that same money might result in greater carbon reductions if spent elsewhere.


London Underground would, I expect, /invest/ $6M in reducing heat in the tunnels. I can't find costs, but there have been other projects to do this.

In the summer, the temperature can rise to uncomfortable levels (over 30°C).


Maybe that's a net figure. Certainly I trust TfL wouldn't be doing it if it wasn't worthwhile - they're generally very well-managed.




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: