The Energon bridge is a massive power source used to transfer Dark Energon to Megatron's Orbital Station which, in turn, powers Trypticon's main cannon.
War for Cybertron
The Energon Bridge is a multi-component device designed to supply Starscream's orbital station with power. It consists of an Energon Production Machine, which creates the Energon and serves as the boss for Chapter 2, a four-legged Energon Projector Machine, which creates an energy beam that is directed into space, several Redirection Rings that allow the Energon beam to criss cross around obstacles to reach the station, and finally a Recieving Station built into the Space Station that recieves the Energon beam and distributes the power to the various parts of the station.
In Chapter 2, Starscream and his Seekers fly to the Energon Production Machine and corrupt it with Dark Energon. The machine attempts to defend itself from the corruption and the seekers but eventually succumbs to the Dark energon and sprouts crystal spikes, sending Dark Energon to the Energon Projector that sends the Energon beam to the Orbital Station.
In Chapter 9, Silverbolt, Jetfire and Air Raid attempt to shut off the Energon Bridge, as it is supplying Trypticon with power. They fail, as Megatron has backup systems, and end up destroying his transformation cog instead. (You have to wonder; why didn't they just go underground like Starscream did and shut it off from there?)