Energy is an essential part of the gameplay in Valerian: City of Alpha - you can’t attempt missions or send your shuttles between galaxies without it.
Fortunately, Energy can be replenished while shuttles are out exploring the universe albeit at a slower rate. If you have a shuttle that is running on a nearly empty tank, you can always recall it back to Alpha at no energy cost. There it can be refueled with Energy at a much faster rate while it’s sitting in the Docking Bay.
But if you’re in the middle of an exciting space adventure and you really don’t want to interrupt all the action, you can instantly refill a shuttle’s tank by spending small amounts of Simors. If you fail a mission, it might cost you some Energy. So you should make sure that you double-check the difficulty level of a mission before you start with it.
Each shuttle has a unique regeneration system and some can replenish their energy while in space faster than others. If you find yourself getting frustrated with how slowly a shuttle’s system is running, you can craft new shuttle parts for it in the Factory. This will make it run much faster, which will allow your Agents to stay out in space for longer periods of time. If you’re looking for even more efficiency, there’s the Energy saving mechanism on each shuttle that will further lower your fueling costs.
So, needless to say, Energy is a very VERY valuable resource that you should keep an eye on.
The more you have, and the smarter you use it, the more you’ll be able to accomplish within the universe of Valerian: City of Alpha.