The Old Ener-D was created by Dr. Fudo, Roman Goodwin, and Rex Goodwin. It was created after Dr. Fudo discovered Planetary Particles by R.R.D., it was the main power supply for all vehicles. However, it began to rotate inversely, and Dr. Fudo decided to stop the project before it could lead to the disaster, Zero Reverse. Roman wasn't satisfied, and R.R.D. refused to stop the project, under the leadership of Roman Goodwin. Roman made the project resume, which lead to his death, Zero Reverse, and the creation of the Dark Signers.
Z-one tried to use the Old Ener-D to destroy the new momentum before it destroys humanity.