If you've ever hankered after a hydrogen-powered business jet, your wait might not be much longer. French aerospace startup Beyond Aero's BYA-I One aircraft has completed its Preliminary Design Review, pushing it along the path to certification.

On paper, a hydrogen-powered business jet seems like a good idea. Hydrogen is about as green a fuel as you can get, producing only water as an emission and by using a fuel cell that runs electric propfans the resulting noise is much quieter than conventional gas turbines.

Mind you, there are a number of drawbacks, aside from not having anything like an actual hydrogen economy to supply the fuel – and certainly not one that doesn't depend on fossil fuels. Compared to conventional aviation fuel, hydrogen has a very low energy density, so you need a lot of it to do the same job. This is made worse by the fact that handling cryogenic hydrogen is extremely difficult, expensive, and requires a lot of specialized gear.