It's quite common. Except that there are no batteries (battery won't do, you can't charge it fast enough), you just need to have another train in the same secti

It's quite common. Except that there are no batteries (battery won't do, you can't charge it fast enough), you just need to have another train in the same section to consume it (or whole network, if your converter substations are ready for that). Energy savings estimates were like 10 to 20 percent (don't have any link for this, it was some British study I remember, sorry).