I thought in insurrection that they used the buzzards to scoop up the flammable gas into tanks then release it behind it..
And to release the hydrogen in that sleepless episode..
You can always use more fuel! And as insurrection showed, can scoop up other useful gasses..
Can always dive down into a gas giant for fuel as well.. Why that voyager episode running out of fuel was bullcrap.. Or newt crap...
Voyager had many kinds of crap.
Maybe every single kind.