Nelson,
The MythBusters actually proved that an engine can run on hydrogen. The technology is no different than converting an engine to run on LP gas or compressed Natural gas.
The MythBusters just waved a hose from a hydrogen tank over the carburator and the engine started instantly. The engine ran very well for a few seconds before it backfired and ignited the hydrogen coming out of the hose that Jamie was holding and he quickly turned of the gas.
If the engine was properly converted to run on hydrogen, like and LP or Natural gas powered engine, it would work just fine.
The biggest problem with using hydrogen is that a tank of hydrogen is highly explosive, and a single spark during an accident could set off the hydrogen like a bomb. The unique thing that these "Run on Water" engines do is create their own hydrogen from water on the fly. There are no large hydrogen storage tanks and much of the explosive danger is removed.
The other problem with hydrogen and some of the other alternative fuels is that there is no distribution networks and no service stations equiped to pump hydrogen. The breakthrough in generating your own hydrogen from water onboard the vehicle is the fact that gas stations could easily and quickly convert their existing gas pumping equipment to pump water, and you could fillup at home with your garden hose.
Some of these water-to-hydrogen systems use salt water and sea water could be an inexpensive source.
Even the much touted fuel-cell technology runs on hydrogen. Instead of powering an internal combustion engine, they use it to generate electrical power.
...Rich