When I was an undergrad in the late '80s in Materials Science, there was a professor who had developed a yttrium based alloy he called a "hydrogen sponge" -- it would soak up hydrogen and leave it inert in this alloy until a small electric current passed through it. This would release the hydrogen, which he was hoping would go into a small ceramic-block combustion engine - since hydrogen combustion is around 95% efficient. As a bonus, the process of releasing hydrogen was endothermic, so the hydrogen sponge was also the air conditioner. I wonder whatever happened to that technology? It had drawbacks in the alloy was heavy -- and the some of the same hydrogen generation issues that the current fuel cell cars have. But storage and transport worked better than what we have today, and hydrogen ICE should be less costly and more efficient than a fuel cell.