Wikia

Tylium is a substance used as a power source.

The primary reactor coils on Quarra process more than 8,000 metric tons of tylium per second, with a 94% thermal efficiency. (VOY: "Workforce")

Hirogen warships utilize a tylium-based power source. (VOY: "Flesh and Blood")

This is likely a reference to Battlestar Galactica, in which tylium is also a power source.[1]^{(citation needed • edit)}

Tylium