A AirShip is a cross between a balloon and plane. In essence, you have a large bouyant bag of gas and some propellers.
AirShips are quite a well developed technology, although in general they are used for things like advertising blimps. Their main problem is that the are relatively slow, compared to ground transport or a plane. However, they are also a very efficient form of transport, taking very little Energy to move quite large loads.
These days most AirShips use helium for bouyancy. In terms of bouyancy, helium is not as good as Hydrogen, but has the big advantage of not being flammable; this has been a major concern ever since the Hindenburg disaster. However, the use of helium makes AirShips much more expensive, because extracting helium from the atmosphere is expensive.
I think that worries over Hydrogen AirShips are excessive. Firstly, technology has advanced a lot since the Hindenburg. A Hydrogen AirShip would be made from much better materials these days, much less likely to explode. Secondly, Computer technology has advanced a lot; entirely automatic AirShips are now much more plausible. They could be excellent for gathering and moving BioFuel around the world, as well as potentially moving Hydrogen itself.