Badnik Processing Plants are both a prison and a robotics factory where Badniks are constructed. Prisoners and slaves are rounded up and taken to these plants where they are installed inside Badnik shells as organic batteries. Dr. Robotnik had built dozens of these facilities during his rule over Planet Mobius. They were all shut down on the day of the worldwide electromagnetic pulse that caused the destruction of Robotnik's empire.
When Robotnik first attempted to gain control of Mobius, it wasn't altogether clear how Badniks were made. On one early occasion, a Badnik itself acted as a mobile plant, threatening to imprison Tufftee and turn him into a Badnik.
Ruled by Robotnik
With Robotnik's overnight capture of Mobius, Processing Plants quickly became a very real punishment for Mobians that didn't keep in line. They were often forced against their will to pollute Mobius or spend all their earnings on funding Robotnik's campaign and, when they refused, would be rounded up and turned into Badniks. Sonic the Hedgehog and the Freedom Fighters often reversed these efforts, but rarely made an impression on the sources themselves.
One of the most feared Badnik Processing Plants was the Veg-O Fortress on Mount Mobius, although it was never seen. Robotnik once made the decision to round up every last one of the Emerald Hill folk and convert them there, but the operation was thwarted by Sonic and Captain Plunder. Little is known of what happened to the mountainous base, but the heroes were never shown to infiltrate it.
The Emerald Hill Zone was never spared from the threat of conversion. Robotnik's Troopers made regular raids on the Zone to replenish his Badnik supplies. One such day saw the capture of Hopper, although he would be freed shortly after. The kidnapping was gatecrashed by Shorty the Squirrel, who attempted to interrupt the procedure and free Hopper, although all it succeeded in doing was "volunteering" himself to become the new Cybernik. By tampering with the plant's controls, "Shortfuse" was able to keep his free will.
For attempting to sabotage Robotnik's plans, former employee Tekno the Canary was sent to the Badnik Processing Plant along with several other citizens but was rescued mid-journey by Shortfuse.
Although Processing Plants were heavily guarded by Troopers and newly-created Badniks, Sonic and his friends made occasional efforts to destroy these facilities and liberate innocents. An early attempt was achieved when intelligence suggested that "Robotnikcon One", a convention set up with the sole purpose of celebrating Robotnik, was actually an undercover Plant. Despite Porker Lewis' protestations, the unwitting civilians pored into the facility, only to emerge as Balkiry and Buzzer Badniks. With the area cleared, Sonic destroyed the building with a giant Robotnik statue. A similar operation involving "Doctor Sun" was also halted.
Following the destruction of the second Death Egg, Sonic vowed to get every Emerald Hill villager to safety. Although many of them were easily relocated to the Floating Island, many were still in captivity, awaiting to be processed. One daring excursion saw the Freedom Fighters break into a Plant disguised as Badniks. They were quickly rumbled, forcing Sonic to fight the lizard guard whilst the others escorted the prisoners out by Star Post. The last few prisoners held in Metropolis City High Security Prison were also freed, although it took a transformation to Super Sonic to repel Robotnik and destroy a robot spy.
Robotnik began to lose his grip on the world and sought other ways to robotise his subjects. He developed more secretive methods, such as hiring Max Gamble to construct the Pit Plunge Roller Coaster, a rollercoaster leading to an underground, mobile Plant, which would be destroyed by Shortfuse. As opportunities dwindled, pending Badniks were forced to wait in squalid prisons (with one guarded by Plasma), making it easier for Sonic to free them.
EMP and beyond
Thanks to the intervention of the Black Asteroid and the electromagnetic pulse, all technology on the planet was shorted out and the Badnik Processing Plants essentially became useless. Robotnik was deposed and moved to Flickies' Island, where he turned the Rusty Ruin Zone into a bespoke base and Plant, using Flickies as his new power source.
Robotnik was not the sole user of such technology. Like Commander Brutus had done before to create his own robot army, the know-how to build such a facility was loaned out to the Woodzone Leader as a means of creating a Badnik army in anticipation of Robotnik's return. The smalltime operation was ended by Tails, but the hero was left puzzled over how he gained the technology.
Return to Power
Much later, the return of Robotnik as a digital threat led to Mobius falling into a time of war. Although it took a while, Robotnik began utilising Badnik Processing Plants once again, namely the use of Flying Batteries to transport the Detonik line of robots.