I guess it's less about how much energy per passenger, but what the energy source is. A plane or jet have to fight hard against the atmosphere to defy gravity.

I guess it's less about how much energy per passenger, but what the energy source is. A plane or jet have to fight hard against the atmosphere to defy gravity. That absolutely cannot be decarbonized for passenger flight. But an airship floats. If you're only energy requirement is pushing a floaty thing around you can absolutely decarbonize. Batteries? Probably. How about one of the nukes that powers a sub? No idea! Maybe!