Black hole lightning. For some reason we don't understand, lightning happens on Earth. All models of electric charge say inhomogeneous distributions of charge should immediately equalize on small length/time scales, and yet the giant discharges of arc lightning across the sky show that this does not happen. There is some unknown process driving these large scale charge distributions. Furthermore, lightning is a radio source. The no hair theorem says BHs can only have charge, mass, and angular momentum so charge is allowed on black holes. Assume the process driving large scale charge formation is gravitational in nature (since we have NO idea what it is) and that it drives such formations on BHs too. The discharge of this charge can be the source of the strange one-off FRB signals which never repeat and are random like terrestrial lightning.
I have two models of discharge: one like terrestrial lightning but one exotic. On Earth, large potential differences drive "dielectric breakdown" of the atmosphere such that charges in the atoms of the air move around. You can have this same thing in the accretion disc of a BH: Bh lightning, but I wonder if that could produce the mega energy scale of FRBs which are supposed to be 1000000000 nuclear bombs or something. Maybe dielectric breakdown in an accretion disc could cause that scale, I don't know. Seems like a lightning bolt like that would totally destroy an accretion disc and the discs would be rarer than if they weren't getting blown up by BH lightning. This could also work with nearby matter not in active accretion. That would have a bigger energy scale which increases with the distance of the "air gap" which the lightning has to cross. Since there is no air in space, this requires a lot of energy. Furthermore, active close accretion might lead to small discharges which don't disrupt the accretion stasis.
