Something interesting about locomotives is that they do quite a bit of braking by using the motors as generators, but it’s NOT regenerative braking! There’s basically no electrical storage system that can handle that amount of energy that quickly, all batteries available today can NOT handle that kind of power surge safely. Some catenary systems can handle back-feeding, and it’s becoming more common, but it’s not something a diesel-electric can do. Instead they have massive resistors and radiators at the top of the locomotive and they bleed it off as heat. It’s less wear on the brake pads, so it’s often preferred when they don’t need to stop quickly.
Imagine a flywheel system on a train. The beautiful sound as it spins up while coming in to a station…
Why couldn’t catenaries handle the power being fed into them? Seems like they’d be able to handle up to whatever the max power output for driving the train is.
I seem to remember some old story about electrified rail going over some mountains and the first run was actually net negative in terms of energy consumption because it was more downhill than uphill.
They could even install catenaries incrementally only on the hardest and most common braking areas (which are often near population centers with infrastructure that could easily absorb the electrical spike) so it’s not like the total network needs to be electrified for this option to work. But nobody wants to spend any money and no government is ever going to force them to, so we’d apparently rather be completely reactionary and wait until economics eventually makes it make sense to them, because thinking and planning ahead for things beyond the current financial quarter is too difficult for us these days.
I’m not an expert, but I think it has to do with AC vs DC electrification. With a DC third rail subway you can just feed it back into the lines no problem, but with AC you have to get the phase sync exactly correct or it will cause pretty serious problems. It’s the kind of thing that depends a lot on how old the system is, how energy distribution works, etc.
If there is an actual expert here I’d also like to know more…!
That makes a lot of sense.
