Except not really, as it's quite difficult to float a barge across a continent.

In that case, they're competing with trains.

Trains need tracks, barges need rivers, trucks need roads.

A cargo airship needs a clear field, and probably some really good tie-downs -- dropping off one or five thousand kilograms of cargo will produce a major lift imbalance.

Yeah, ballasting is often forgotten when people talks about huge cargo airships.

Yes, it can drop a huge generator into the middle of nowhere for your construction project, but unless you do something it will then shoot up to the stratosphere due to all the extra lift.

Still, its solvable with either some rudimentary infrastructure (pump water aboard as you unload cargo) or by removing some of the lifting gas (much less of an issue with hydrogen).

Don't you just need to compress some of your lifting gas? Just pump/compress it into a tank, reverse it when you need the lift?

There is (was?) an effort to restart Airships for cargo traffic. They solved the ballast issue with onboard compressors. If understood it correctly that solved this problem complete with [effectively?] no loss of lift gas.

Interesting! Setting the weight of the compressors and the energy requirements (I guess you could supply that ground side if possible) it really does solve the issue of loosing helium. :)

For hydrogen you I guess you could either let it go or also use the compressors in case there is no way to replenish the lifting gas & you might need the extra lift before returning to your primary maintenance base.

Right but now you're consuming energy to run those compressors, making the energy-savings moot. If you look at the history of airship development (which admittedly is ancient by modern technological standards), there were several incidents of airships floating away from their mooring. Mooring an airship is actually a fairly difficult problem.

Energy usage for compression is tiny compared to actually transiting, and you can get some of the energy back. Or if it was hydrogen fueled, just run your engines for a short time.

Or, just have the compressor ready at the dock, and wait with the unloading until the hydrogen has been compressed.

But yeah, simply running a compressor powered by hydrogen should suffice. I assume the airships would require some surplus hydrogen anyway, in case there's a mid-flight leak or something.

Fair enough you're probably right. And if you have a battery onboard and charge it using solar cells on the ship, you should have enough energy generated to at least run the compressor and dock the ship.

This might be slow, but what about using the lift gas in a fuel cell with atmospheric O2 for extra efficiency? You reduce the lift gas in the bags, and if you store the water aboard then you get extra ballast. You could even “unload” the extra electricity for use groundside.

The corollary pipe dream here is to line the entire interior of the envelope as a fuel cell membrane and use the airship as a portable battery.

IIRC some military airships condensed water from their their engine exhaust to keep better control over their balance (the ship otherwise gets lighter as you burn fuel and you might have to release some of the irreplaceable lifting gas instead).

Cover the whole outside of the blimp in solar panel foil? I do not see energy as the problem.

This is only really an issue with Helium. When Hydrogen is your lifting gas, you can use it with fuel cells to power the cranes, producing water as a further ballast.

In the hypothetical hydrogen powered future, cargo Zeppelins could pull double-duty as a hydrogen tanker.

In the case of hauling gensets around, that would basically make it a fully self-contained power plant.

Also confidence of calm weather until it reaches the next field, no? I'm not sure how strict a constraint that'll be.

Curiously enough, virtually everywhere with any significant human activity exists ... near ports, roads, rivers, or rail.

Roads or tracks can be quickly laid through wilderness if necessary (provided the natives are friendly).

If you're dealing with frozen terrain, ice roads can be used.

There are some exceptions to this. They are extreme outliers, both figuratively and geographically.

The NIMBYs would never allow a hydrogen fuelled airship anywhere near anywhere.

They make a lot of sense in the north (northern Canada and Siberia) where roads and railway are not economical or not possible because of permafrost.

Western Europe uses its rivers and hundreds of thousands of km of canals to ship between a quarter and a half of its freight this way. It's the most economical and environmentally friendly form of transport. Youre right that this sort of infrastructure does not come cheap, which is why hydrogen dirigibles are very interesting.

That's nice in Europe, great that it has that system. But that doesn't work in North America (east to west navigation across continent impossible by barge), Asia, Africa or South America.

May I introduce you to the emergent advanced experimental technologies of the shipping canal and river barge?