You can use liquified hydrogen which need to be chilled and insulated, and will evaporate away in a short time if not properly sealed
Or you use compressed hydrogen which means you are basically carrying an IED that weighs several hundred kilograms with the amount of pressure inside the gas tank
And hydrogen combustion is as others have said, inefficient.
Another issue is that you also need to use basically pure oxygen if you want to use a hydrogen fuel cell, otherwise the catalyst inside the cell would get poisoned
And well, there is a car that did all that, the Toyota Mirai, but that also pretty much ended in commercial failure, due to lack of hydrogen filling infrastructure and a whole load of other reasons.
You can use liquified hydrogen which need to be chilled and insulated, and will evaporate away in a short time if not properly sealed
Or you use compressed hydrogen which means you are basically carrying an IED that weighs several hundred kilograms with the amount of pressure inside the gas tank
And hydrogen combustion is as others have said, inefficient.
Another issue is that you also need to use basically pure oxygen if you want to use a hydrogen fuel cell, otherwise the catalyst inside the cell would get poisoned
And well, there is a car that did all that, the Toyota Mirai, but that also pretty much ended in commercial failure, due to lack of hydrogen filling infrastructure and a whole load of other reasons.