Energy flux was a power system used in starships of the Romulan Star Empire in the alternate reality created by the temporal displacement of the Narada. The energy flux system allowed starships to temporarily access unlimited energy reserves. Centurion-class, Cetratus-class, Gladius-class, Patronus-class and Securis-class starships could all utilize the energy flux system. (TOS video game: D-A-C)