Sorry Sygyzy..
.. but your first reply was factually wrong ..and a tad abrupt!
Those DC motors will have to incorporate reduction gearboxes to substantially reduce the motor's speed to the desired mainwheel speed ... and with such substantial reduction will come the benefit of hugely increased torque .. DC power from the APU (sipping fuel!) will be more than adequate. In any case, there is more than just fuel consumption here; there is a continuing need to satisfy the environmentalists and Greens that the reduction in air pollution which results from long taxy-runs (before take-off and after landing) .. is being reduced as far as practically possible. My single concern would be commencing a take-off roll just a minute or two after engine-start.. even with all Ts and Ps in the green; but I guess the engine manufacturers know best about that. Almost silent taxying then..rabbits and hares beware! TP