"The most efficient, and safe, hydrogen storage medium has already been found.
Its called->> Gasoline..
Yep. About 15% to 16%, versus 11% for water, and extraction is EXOTHERMIC - it fuels itself. I suspect that when supplies run low, we will just make more. Perhaps we will make pure iso-octane, or perhaps something lower weight, like propane, that can fuel the same engine. Diesel might be better, but much harder to manufacture.
Finally, I think that hybrid vehicles - or actually, what might be called "pure-hybrid" vehicles, that use pure electric drive and a disconnected generator, are an important step forward. It's not new - a major sector of commercial transportation already runs this way, on rails all across the country.
First, the generator can then be any technology, depending only on the state of the art. Diesel rotary and various fuel cell types, both PEM (H2) and solid-oxide (gasoline, alcohol, or LNG) come to mind. But the most intriguing possibility in my mind is something like a trolley or slot-car pickup device, that could bring in external electric power directly from the grid. This is so much more efficient that running ALL of our vehicles on the electric grid would require a generation capacity expansion of only a few percent.
Perhaps it's a wild idea, and I don't pretend to know how to do it. The infrastructure required would be expensive, and potentially intrusive. A foolproof metering system would be required. But the convenience factor would be very high - you would move on and off the grid at your own convenience, using self-generation only when needed. Unadapted vehicles could share the road with adapted ones. Oil consumption AND pollution would be minimized drastically. I would think that city centers and major intercity routes would be the places to start.