In the depths of Iacon is the Iacon Energon Refinery, literally the source of much of the Autobots' power.

Fiction

Titan Prime comic

During the war, Megatron attempted to cripple the Autobot war effort by staging a commando strike on the Iacon Energon Refinery. He led a team of five into the refinery, only to find that Optimus Prime had anticipated the attack and set up defences. The Decepticons walked straight into a trap and were pinned down by Autobot fire. After the other three team members fell, Megatron caused a distraction by shooting some of the Autobot gunners while Soundwave went to plant the last bomb. Soundwave was injured, and Megatron mounted a rescue mission of his own. Optimus's surprise at his opposite's compassion caused him to hesitate, and Megatron set off the solitary bomb they'd planted, allowing the Decepticons to escape. War Story