It got me wondering if the increase lift capacity would be added factor, but quick calculation shows that it would only gain an extra ~1% of lift. So it would really just be a cost question: https://en.wikipedia.org/wiki/Lifting_gas
> Venus has a CO2 atmosphere. Because CO2 is about 50% denser than Earth air, ordinary Earth air could be a lifting gas on Venus. This has led to proposals for a human habitat that would float in the atmosphere of Venus at an altitude where both the pressure and the temperature are Earth-like.
One cost-reduction approach would be that the beams could be mass-produced for efficiencies of scale. The top panels could be simply plastic sheeting.
1. Hot air balloons get their lift from hot air; and,
2. Dirigibles can get their lift from hydrogen; thus,
3. Hot hydrogen dirigible?
Blah blah blah ... exploding dirigibles ... blah blah blah. The lifting efficiency is outrageous.
You'd want to be damn sure about the reliability of your thermocontroller though.
I have often wondered about super strong materials, a sphere with vacuum inside.
Air is about 30 grams per mole and hydrogen is two grams per mole. So going entirely weightless you could go from 28 grams of lift per mole to 30 grams of lift per mole, a 7% increase.