To make refueling more efficient, could it be made a single-click action? If there are no future plans to create different types of fuel cells, there's really no reason for me to click refuel, have a little box pop up with the image of a fuel cell, and then have to click on the fuel cell.
Instead, we click refuel, and it automatically puts in the cell, the growl saying, "You refueled a ____. You have ___ fuel cells left in your inventory."
If you don't have a fuel cell in your inventory, then make the refuel option greyed out, and when hovered over, say, "You don't have any fuel cells!"