Innovators gear up work on ‘green’ hydrogen plane with plans for nonstop 9-day trip around Earth

Make it so!

An easier and safer way - convert hydrogen into "green jet fuel," a process called "Power-to-Liquid (PtL)" is used, where the hydrogen (ideally produced from renewable energy sources like solar or wind) is combined with captured carbon dioxide to create a synthetic liquid hydrocarbon that can be used as a sustainable aviation fuel (SAF), essentially creating a carbon-neutral jet fuel.

Which can actually be used in most present day plane engines - only its more expensive than tradition fuel.

The plan to use cryogenic cooling means this will fail. Run some numbers. refrigeration to those temperatures is hard. Keeping things that cool is hard, even for temporary storage, perhaps overnight so there's power to keep the plane flying when the sun isn't providing solar energy.

There are other methods to store hydrogen that can be easily released on demand later, but not the same amount. Nowhere near the same amounts.

Converting water into H₂ and O₂ is energy expensive. I have doubts that layering multiple inefficient methods just to use hydrogen makes sense, but they have to try and a platform like this is as good a place as any.

I think they need to base their aircraft on a glider-like platform too to have a a very long, efficient glide ratio over 1:50 (gliders are usually around 1:70). Commercial aircraft are 1:20 or so ... the F-4 was 1:5 - proof that a brick can fly if you connect 2 powerful engines to it.