[iamthemonster]

Until I got to the last line I assumed this was about safer transmission of hydrogen, not lift gas. Of course it would be uneconomic for pipelines to have 91.5% inert carrier gas but I wonder if you could use an inert refrigerant gas to make "non-flammable hydrogen mix" within piping that runs to consumers through non-zone-rated or even residential areas, and then refrigerate the gas at point of use, to leave a pure hydrogen stream? The refrigerant would just go around in a mostly-closed loop.

Incidentally, using 8.5% hydrogen as lift gas will make a gnat's fart of difference; the lift force is proportional to the difference in density between air and lift gas - both helium and hydrogen are way less dense than air.

[ivanbakel]

>Incidentally, using 8.5% hydrogen as lift gas will make a gnat's fart of difference; the lift force is proportional to the difference in density between air and lift gas - both helium and hydrogen are way less dense than air.

My understanding is that the intention is not to create a mixture with better lift, but which is cheaper - helium being significantly more expensive than hydrogen due to supply issues.

What few sources I can find online for elemental prices suggest helium is anywhere from 2x to 10x more expensive than hydrogen, by weight. Even an 8% substitution would be economically significant at those prices - although, as the submission says, you may lose those margins through the bad reputation of hydrogen as a lifting gas.

[blippage]

But if you lower the temperature, the hydrogen increases in density.

I haven't read the article, but I presume that the use of hydrogen is a non-starter. No-one wants a flaming fireball raining down on them.

[bryant]

> I haven't read the article,

lol. tl;dr (apropos in this case): "So, 8.5% hydrogen in helium appears to be non-flammable, whereas anything above 8.7% is flammable. Eight percent hydrogen really doesn't provide much in the way of cost savings. You probably ought to consider another question concerning your airship business. Are the cost savings by using a 8.5% mixture of hydrogen worth all the trouble and effort it will take to convince your customers that the mixture is safe, as opposed to avoiding the safety questions altogether by using 100% helium?" [implied: probably not]

> but I presume that the use of hydrogen is a non-starter. No-one wants a flaming fireball raining down on them.

it'll probably work just fine on coastal or oceanic automated shipping routes. And oceanic routes would slightly mitigate the risk of someone catastrophically holepunching one with a Class IV laser.