I can get behind the round-trip inefficiencies if it gets terribly cheap, but I can't imagine how storage and transportation can ever be economical.
We are trying to contain the most volatile substance in the universe. It needs incredible pressure just to be manageable and even then, it freaking diffuses within the steel walls themselves, leaking and making it brittle over time. It's not hard to imagine single protons wandering by in high pressure H2.
I mean, it's doable, but economical? It's hard for me to believe it ever will be, no matter the scale.
Both are easily carried in a Dewar flask. LH2 takes up more room, but that is just a matter of how big the ship carrying your flasks is, and how many of them. The number of kg in a flask of some volume is much less, but you also need to oxidize many fewer kg to get the kWh you paid for. The ratio is not 1, but is much less than 450/70.
There is nothing special about the size and laden mass of the LNG vessels we use. It was chosen by immediate convenience. Details of vessels for LH2 will be chosen the same way.
We are trying to contain the most volatile substance in the universe. It needs incredible pressure just to be manageable and even then, it freaking diffuses within the steel walls themselves, leaking and making it brittle over time. It's not hard to imagine single protons wandering by in high pressure H2.
I mean, it's doable, but economical? It's hard for me to believe it ever will be, no matter the scale.