The back end (left hand side) is the batteries. This piece of equipment weighs in at about 6 tons and can move as much in it's bucket. It is battery over hydrualic (IE all of the motors are hydrulic). You can see the operators compartment just behind the front wheel (the thing with the little safety chain).
Not relevant here, but just wanted to show what a good wet cell array can do.
Yes, I have been in large wet cell room for a data center, about 1400 deep cycle wet cells. Not something to take lightly due to the HUGE amount of current available on the bus bars. Like I said that scoop power plant is enough to make you wish you never got near it. The cells are all tied with metal bus straps. The coal dust (carbon) is a good conductor. Lean over and touch the cells while your watering them and you can end up right on your butt.... and thats just from carbon tracing. I can't imagine getting between the poles, I imagine you could get kilt ded rather quickly.