Nucleogenic energy is a force which can be used to drastically augment a vessel's warp drive, allowing a properly-modified ship to reach speeds otherwise unattainable using traditional propulsion technologies.
In 2376, the crew of the USS Equinox, a Starfleet vessel which had been stranded in the Delta Quadrant, engaged in criminal experiments to enhance their warp drive by murdering a series of nucleogenic lifeforms, and converting the remains into a crystalline compound from which they could extract the energy. This presented the crew with the possibility of returning to Earth in mere months. Their activities were eventually discovered and halted by the crew of the USS Voyager. (VOY: "Equinox", "Equinox, Part II")