Could that chameber in the autobot base, be how they re-energize (Reload on energon). Well it's also been used kinda like a sleep chamber (Out of his head), And a Decontamination chamber (Darkness rising part 2). But in One shall rise, They Cured Raffy by putting him in the chamber and irradiating the bad stuff away. It also appears that energon is injected (Stronger Faster, Scraplets). If that is so, How the pit is starscream gonna be using energon if he doesn't have the equipment for it? He has no allies, He has no equipment for either changing it's form or even for intake, He's also wanted by both factions. The only possible way I can think of is to stick it in his chest like Dark energon or to ingest it orally.