Originally Posted by
ZeroTT
If there is any use case for burning hydrogen... it’s airplanes. Converting the US 121 fleet to hydrogen would require building 500 hydrogen stations. They are probably more gas stations than that in Rhode Island
Those would be rather large gas stations. Look at the fuel tanks at any big airport... you'd need almost four times that volume for equivalent liquid H2 (7-8 times for pressurized H2).
For clarity, "converting" the fleet would mean scrapping all of the existing aircraft and building all-new ones designed for H2. You *might* be able to repurpose existing engines, but I'm sure you'd have to modify the combustion chambers.
Also... there is some concern that jet airplanes injecting moisture into the (normally dry) stratosphere creates a greenhouse effect of it's own. Water is a byproduct of all IC engine operation... it's the ONLY byproduct of H2 combustion. SAF might actually be better for greenhouse purposes than H2.