Why Don't We Just Run Internal Combustion Engines on Hydrogen?

A guy made one like 30 years ago that electrolyzes water into hydrogen and oxygen, then pumps into a normal internal combustion engine.

https://www.youtube.com/watch?v=zZ2QciCN5Ks

https://en.wikipedia.org/wiki/Stanley_Meyer%27s_water_fuel_cell

Stanley Meyer died suddenly on March 20, 1998, while dining at a restaurant. His brother claimed that during a meeting with two Belgian investors in a restaurant, Meyer suddenly ran outside, saying "They poisoned me".[1] After an investigation, the Grove City police went with the Franklin County coroner report that ruled that Meyer, who had high blood pressure, died of a cerebral aneurysm.

I found it. I made a small version of Stanley Meyer's device and made a little torch for a hobby project like 5 years ago

• https://www.youtube.com/watch?v=WLfFpDYDrS8

• https://imgur.com/a/FXxL8dN

Because ICE's are inefficient, it's much more efficient to use the hydrogen in a fuel cell creating electricity for electric motors.

I've heard a few reasons.

First and most obvious is the explosive potential. This goes beyond just one car going up. Shrapnel from a single explosion might cause a chain reaction of other cars. Logistics of transporting bulk hydrogen are certainly more expensive as a result.

Second one I've heard is that hydrogen is harder to store than propane. I'm no expert on the science, but I've heard it said that the smaller size of the atoms makes leaks more common. Don't quote me on that.

Third is emissions. IIRC, hydrogen emissions include some sort of nitrogen molecule that is really bad for the lungs. I'm unclear on if this is any worse than oil-fuels. Again, not a scientist, but I'm sure there's some articles that cover this. The emissions from plants that would produce the hydrogen must also be considered.

I think any real future for hydrogen power will lie with on demand production. As pembo mentioned, there have been some interesting experiments with electrolysis, but I believe the electricity required is prohibitive. Perhaps once solar cells become more efficient, a hydrogen-supplemented combustion-electric design will come around. Time will tell.