An interesting problem...

Generally speaking, yes. Like I mentioned, there will be some trade routes where this isn't true - but for the most part there are refuel depots everywhere.
Howard Day said:
In addition, you can hire a fuel tanker for longer trips, if you like - but you have to pay for the ship, the fuel, and then protect it while you travel. There will be a few long stretches where this is the only option to get from point A to point B - so naturally there'll be pirates galore. Fun for everyone!

Only hope, that when I will play a pirate, there will be NPC merchants flying with their tankers. Let's say I'm blowing out tanker's escort ship - tanker (or any rich merchant) is at my mercy. What about adding an option, that NPC is trying to pay for his/her life offering its assailant money. If I decline, I can blast them, but if I accept and still decide to get a kill the reputation of my "pirate" honor (anyone remember parlay from Pirates of the Caribbean - pirates must have an honor too! ;) ) will start to bear stains and nobody will ever offer to pay for his life in future encounters, also my pleas for mercy will fall on deaf ears. What do you think about that idea?

EDIT: Damn, everything was already answered here. I've just finished reading all the posts on Pioneer thread and I know now, that something like this is going to be implemented. So you don't need to bother with answering. :)