This thread seems to be divided 50/50, with some advocating no fuel, some advocating more fuel usage. I think the fuel should be hard to come by EARLY ON, since the first few quests are all about finding fuel for your ship, since it ran out. As you go to harder planets, fuel becomes more commonplace, and should be something mineable, that way you don't get surface scanners, who solely sprint across the surface of a planet for the loot that exists there. Uranium should be the fuel, and on it's own, should be less efficient and not used for crafting. But in order to encourage base building, an enricher could be produced that would allow it to be crafted, and utilised as a much better fuel source. The refiner would take up Large amounts of space. Too much for your ship to hold, that way people wont sit in their ships with all their materials stored in there.