"Airbus has won a patent for a hypersonic passenger plane, but Concorde’s hydrogen-powered successor is unlikely to leave the drawing board any time soon.
"The proposed aeroplane would cut the journey time from Paris to Tokyo from 12 to under three hours. The idea, first published in 2011, is to use three different kinds of engine power to jump above the atmosphere while still using regular runways for takeoff. It has now won approval from the US Patent Office.(...)
“'Airbus Group and its divisions apply for hundreds of patents every year in order to protect intellectual property,' a spokesman said. 'These patents are often based on R&D concepts and ideas in a very nascent stage of conceptualisation, and not every patent progresses to becoming a fully realised technology or product.'"
It doesn't look like fuel cells are involved here...
Guess more likely Airbus' interest in FCs is linked with Auxiliary power units (APUs) that operate on the ground.
Yup, I like asking unanswerable questions because I know there's someone here who has all the answers. However, since you ask, the answer to the above is "more than we can possibly afford". But I'm sure you have more precise figures.
BTW, I still believe in human mind, teakettle. I bet that even you, if you ever start reading books, will sooner or later (most likely later) tell the difference between a real question and a rhetorical one.