If I understand correctly, this makes use of a hydrogen fuel cell for electric power, and then has that turn electric fans. In general, a modern fuel cell is ~

If I understand correctly, this makes use of a hydrogen fuel cell for electric power, and then has that turn electric fans. In general, a modern fuel cell is ~60% efficient at turning chemical energy into electricity, and an electric fan is ~4x as efficient at turning electricity into thrust when compared to a turbofan engine turning chemical energy into thrust. So ignoring transmissions losses (which would probably be really low anyway if ran on superconductors...) you'd need about 40% of the power of a modern jet to do the same work. There is clearly a lot of scaling work needed, and I don't see a fuel cell/electric aircraft beating existing ones anytime soon if you ignore the emissions, but at least this clearly shows that there is a future for mass commercial aviation once burning carbohydrates is no longer acceptable.