Airships as public transport Yay or nay?

[Lvl 2 Expert]

Cold fusion could make airchips more viable. IIRC many forms would produce helium as a byproduct; hydrogen into helium seems to be the most basic fusion reaction. (and while hydrogen can also be used to float a balloon helium is safer because it's a noble gas and won't burn in oxygen (I'm not sure whether it will burn in chlorine trifluoride but I'm willing to wager it won't even burn in then) whereas hydrogen burns quite readily

Well, sort off...

Instead of restating the reasons I think zeppelins were always a bit of a long shot (I prefer ekranoplans if we have to travel weird anyway) I decided to calculate if nuclear fusion could contribute significant amounts of helium. The energy density of deuterium used for fusion (presumably turned into helium, the page doesn't quite specify) is around 4 million MJ/L. A cubic meter of helium can be used to lift roughly a kilogram of mass off the ground. So that's 1000 liters. Assuming we can make an airship where the ship weights half of the load it can take in passengers and freight, and assuming 70kg standard humans each with 30kg of clothing, luggage and inflight meals, an airship made for 100 passengers would weight around 15,000kg when full, thus requiring around 15,000m^3 or 15 million liters of helium. 15 million times 4 million is 60 trillion MJ or 60EJ (exajoule, 10^18 joule) of energy produced in the process of making that much helium (more if you can start from regular hydrogen, but we're disregarding that for now).

How much is that, 60 exajoules? Well, roughly the yearly energy consumption of South Korea, or one tenth of the yearly energy consumption of the US. That means this is actually sort of feasible, assuming most of our energy would come from fusion, the number of airships stays small (think more private jet, less vacation liner) and we don't develop a shortage of helium due to other applications, like needing a lot of it for medical scans and electron microscopes or something. Under ideal circumstances and assuming no losses during operation the US could float 10 large airships a year using waste products of nuclear fusion.