Considering Li-Ion's tendency toward thermal runaway when overheated or overloaded, a battery this big would be moderately spectacular if it happened. Presumably, battery management would be a significant part of the project.

I have found it funny how some people want to call a diesel-electric locomotive a "hybrid." But a consist with this thing hooked up like a road slug could actually be a true hybrid with storage. Cable it to the diesels for charging as well as using regen and plugging in at Barstow (lots of solar on the grid in that area).