A highly unstable form of energy generation, banned among the Alpha Quadrant powers, whose detonation wiped out all life on a Delta Quadrant world in Time and Again.
Polaric ion energy can power a civilisation, but an accident can set off a chain reaction that scours a whole planet. According to the Voyager episode Time and Again, research into it was outlawed by the Polaric Test Ban Treaty of 2268 after a Romulan station at Chaltok IV was nearly destroyed.
Voyager is rocked by a shock wave from a planet whose inhabitants relied on the technology and finds every living thing dead. While investigating, Janeway and Paris fall through a fracture in time and arrive a day before the disaster, among protesters campaigning against the power plants.
Janeway comes to realise that the explosion is caused by Voyager's own rescue attempt. She seals the rift, and the catastrophe never happens.