You can use that energy to turn, in the same way that a glider or wheeled vehicle can turn using only their momentum to provide acceleration in a new direction.
Definately.
However, any energy you have to
add to make the turn is not recoverable, as it opposes drag, so it cannot be stored. Its like using the brakes on a engine powered car to come to a stop, you turned your energy of momentum into heat, and it's gone - you did not store it, so now you have to replace it.
If you dive the plane, all other things remaining unchanged, it speeds up, and stores that energy. You can recover most of that energy from the stored speed climbing back up again shortly after. A turn does not work the same way.
For every aircraft, there will come an angle of bank which id great enough that the aircraft does not have enough power to sustain it, then you stall, or exceed a G limit, if you try to maintain it co ordinated.