"High-altitude winds between 1,640 and 3,281 feet (500 and 10,000 meters) above the ground are stronger and steadier than surface winds. These winds are abundant, widely available, and carbon-free.
"The physics of wind power makes this resource extremely valuable. “When wind speed doubles, the energy it carries increases eightfold, triple the speed, and you have 27 times the energy,” explained Gong Zeqi "
Neat.
Any real reason you can’t fill them with hydrogen? A fire can’t start inside the bubble, because there’s no oxygen. If a fire starts on the outer surface, then it doesn’t really matter if it’s hydrogen or not. It’s also cheaper and slightly better at lifting. There is some more danger with handling it on the ground, but you should be able to mitigate that with safety procedures.
Yes the Hindenburg disaster had more to do with the flammable paint used than the hydrogen inside it. But the safety procedures when working with on the ground may be more expensive than just using helium.
Hydrogen is hard to contains long term, it leaks through most materials. I’m no expert on the matter but I suspect the gains in lift would be partly negated by the changes to the envelope of the container.