Simon Michaux has talked about burning iron powder.

My father talked about using powdered iron to power a car fifty years ago.  He knew powdered iron has high energy potential by volume.  My father made it clear to me there is a difference between an energy source and a transport mechanism.  At least nine of ten people do not know there is a difference.  I am being kind.

Using hydrogen in airplanes is just plain nuts.  The tanks to hold the hydrogen take up most of the interior space.  Every hydrogen powered airplane would be equal to a mini nuke, and they would explode.  How are you going to get people to fly on flying bombs?  There is an advantage here regarding car accidents at intersections.  The explosion from a crash will be strong enough to clear the intersection.

If the crater is not too deep cars will be able to use the intersection right away.  They will not need police and tow trucks to clear wreckage.  The wreckage clears from the intersection immediately from the blast, and visibility is improved since everything next to the intersection is taken out as well.  Buildings people plants dogs, everything.  But the explosion is clean.  No toxic residue except from what gets destroyed.   I have to admit hydrogen has potential positive benefits.

But regardless of positive benefits, hydrogen is only a transport mechanism.  Hydrogen is not a source of energy.  You can't mine hydrogen.  If you could mine hydrogen it would be a source of energy.  One way or another all hydrogen must be produced, and that always takes more energy than you get from using the hydrogen.