A microfusion generator was a component of at least one form of propulsion technology in the 24th century.

Microfusion generators were essential in the lives of the Enarans during the 24th century, as were communications interlinks. Jareth once noted to his daughter Korenna how hard it was to relate to the Regressives, a group on Enara Prime who used little more than the most primitive technology, including such luxuries as microfusion generators or communications interlinks. (VOY: "Remember")

In the Federation, microfusion generators were found aboard Defiant-class starships. While initiating the impulse pre-start sequence, it was necessary for the microfusion generators to be on line. (DS9: "The Changing Face of Evil")