Extracting energy from dihydrogen is just a technical problem which should be amenable to a number of practical approaches - finding an economical and environmentally-friendly source of dihydrogen is the real trick. Coming up with safe, dependable and cheap ways of storing it and moving it around is non-trivial as well.
“Coming up with safe, dependable and cheap ways of storing it and moving it around is non-trivial as well.”
You need a big tank to make it useful as well. Nothing beats gas of diesel for a lot of power in a relatively small can.