Volcanic lightning from or to volcanic plumes and dirty thunderstorms is always impressive. In the National Geographic 2017 photography competition these electrical discharges even won the categories of Nature and Grand Moff Winner.
Where does the massive amounts of electromagnetic energy come from? And all the chemical elements?
In a circuit to all those plasma stars, Electric Universe and you?
As the plume started going downwind, it seemed to have a life of its own and produced some 300 more or less normal [lightning bolts] ... The implication is that it has produced more charge than it started with. Otherwise [the plume] couldn't continue to make lightning.
... Volcanic eruptions also release large amounts of water, which may help fuel these thunderstorms.
Dirty thunderstorm | wikipedia