Which is why I wrote it, dummy! -_-
What confused me is your obvious lack of understanding of jet propulsion. See below.
The question posed was, "[h]ow can a jet be electric?", not what's efficient and realistic model for air transport. Stop assuming!
Your response makes little sense to answer the question, hence the confusion. It's like you think "jet propulsion" must require combustion. It doesn't. In fact, in modern jet engines, the vast majority of their thrust (not power) doesn't come from combusted exhaust gas. To make a electric jet engine, all you have to do is cut out the turbine engine core and replace with a powerful electric motor. What you are left with is a compressor fan feeding a propulsive nozzle. No need to go into weird atmospheric chemistry territory to create a pointless intermediary fuel. Just drive the fan electrically and be done with it.
A jet can be fully electric if it uses the atmosphere from the intake to create a combustible fuel and then combusts it. This would require a lot of energy but it is possible since our atmosphere can be broken down into combustible components.
Please explain this miracle of thermodynamics-defying chemistry in more detail. I would really like to have free energy.
which is presumably what these guys did
They are also decidedly tight-lipped about this on their own website, which contains nothing but wishy-washy rhetoric, much in the vein of TFA and this summary. No hard data, no technical details, not even a clarification of what terms like "hybrid" mean. It might be completely legit, but so far this gives off the distinct smell of venture bullshit - seems to fall into the same category of feel-good investment blackholes projects like AirCarbon and Solar Roadways.
But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown.
This circular runway idea falls straight into the "clown" category.
"Catch a wave and you're sitting on top of the world." - The Beach Boys