(covers information from several alternate timelines)
Polaric ion energy was a highly-volatile form of energy based on polaric ion particles. Although polaric ions were capable of generating power on a large scale, polaric ion devices were prone to subspace chain reactions. Such a reaction had the potential of devastating an entire planet, vaporizing all life within a matter of seconds. Polaric ion explosions left behind high levels of polaric radiation, as well as subspace fractures persisting for hours after the event.
In the Alpha and Beta Quadrants, polaric energy research was investigated, but the destruction of a Romulan research station on Chaltok IV by a polaric ion detonation led to the Polaric Test Ban Treaty of 2268. This agreement effectively halted and prohibit all polaric ion research in the Alpha and Beta Quadrant.
One planet in the Delta Quadrant, encountered by the USS Voyager in 2371, was found to be using polaric energy as a planetwide power source. The culture was pre-warp, so contact was not initiated. (VOY: "Time and Again")
In an alternate timeline, the entire civilization of this planet had been annihilated in a polaric catastrophe, but it was found that the shock waves from the explosion had propagated into the past through a subspace fracture. Two members of a Voyager away team, Kathryn Janeway and Tom Paris, moved through one of the fractures and were transported one day into the past, where they discovered that they were the cause of the catastrophe. When they prevented the accident, the timeline in which the explosion occurred was eliminated. (VOY: "Time and Again")