  The energetics of the long duration GRB phenomenum is compared with the BZ
mechanism. A rough estimate of the energy extracted from a rotating Black Hole
with the Blandford-Znajek mechanism is evaluated with a very simple assumption:
an inelastic collision between the rotating BH and an accreting torus. The GRB
energetics requires an high magnetic field that breaks down the vacuum around
the BH and gives origin to a e$^\pm$ fireball.
