Because the Autobots lost most of their Energon reserves in the base destruction, Ratchet returned working on the Synthetic Energon.
Knock Out was able to reproduce the Synthetic Energon from the sample the recovered from Ratchet. He ejected it into his test subject, Cylas and it caused him to become over enraged and aggressive. Starscream orders him to add Dark Energon in to the experiment, so Megatron would be able to control him, but it when wrong and caused a zombie break out on the ship. Cylas escaped and feed off of the Vehicon aboard and they spread it to the other. After the situation was dealt with, Megatron ordered Knock Out to hand over the Synthetic Energon to Shockwave 
Here are some for its side effects.
- Energy Efficiency
- Can be manufacture unlike natural Energon and it counter part, Dark Energon.
- Ruthless 
- To much causes them to burn through their natural Energon reserves.
- When mixed with Dark Energon it may turn them into Terrorcons.