The Quantum Zone has unlimited energy.The extent to which the bands can draw the energy has a upper limit.They are like a hose connected to the ocean.The potential is unlimited,and limited at any given time:it would be very difficult to extinguish a forest fire.And the bands consume their energy store when they have cannot recharge:in the New Universe Quasar consumed the energies of the bands and had to use the starbrand to return home.
It is true though that he could use them much more efficiently.