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Comment by zyang | Hacker News Reader

Hydrogen fusion creates helium as a byproduct. But I don't see why they can't use hydrogen for cargo. We have the tech to make it safer than long haul driving.

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This is a pet peeve of mine when people talk about the advantages of fusion, if you did all of the US power budget with DT fusion that would generate very close to 10 million moles of helium, or 4E7 grams of helium, or 2E8 liters at stp. This is a big number! but it's 2E5 cubic meters and annual US consumption of helium is 40E6 cubic meters, less than 1% of consumption.

The helium-3 market makes an interesting comparison: it's sole-sourced from nuclear fission reactors.

https://cen.acs.org/materials/3-availability-increase-new-su... ("³He availability to increase with new supply deal")

It'd cost $30 billion to fill one of OP's blimps with synthetic helium-3 (which—to be fair—is a superior lifting gas to helium-4).

I found the last sentence confusing

If you produced all the USA's electricity in a year with fusion and collected all the resulting helium with 100% efficiency, you'd have collected less than 1% of the amount of helium we go through in that year.

A naive translation (not checking facts in any way):

Converting 100% of power generation in the US to (deuterium-tritium) fusion would result in 200,000 cubic meters of helium generated per year. But the US currently consumes 40,000,000 cubic meters per year.

Simplified: If you magically switched every power plant in the USA to fusion, they would make about 200,000 cubic meters of helium per year.

But the USA currently consumes 40,000,000 cubic meters of helium per year.

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