Hydrogen run vehicles have been around for ages... there's just no money or drama to be had by persueing it's development.

"Green" hydrogen using solar power certainly works but the process is terribly inefficient, way too inefficient to use for personal vehicles (it's better just to use the electricity directly via storage batteries).

 

But for applications where weight and fast refuelling is important such as aircraft or long-distance transport there's certainly an application.

 

Where we go is going to be an interesting ride.

Making hydrogen is no issue , it is abundant and basically you can make H2 in your room right now . What is a problem is the return of energy . Making hydrogen by splitting with electricity requires much more then you ever can get back . Also , H2 is quite small , in fact so small that you cannot contain it 100% , you will always lose a bit ( a problem for small scale users , since metal become very flammable after using it to contain H2) . Also , H2 is very light , which is a positive for storing it , but on the other hand basically 1l of H2 is actually nothing .

The positives on the research side , solar panels with direct H2 output are being tested right now , and production of them will not be far away , the makes the H2 production more efficient.  2nd positives on that side is that new materials for H2 cells are being developed , since the cells right now contain platinum , makes them extremely expensive . There is progress there on nano materials , which are much cheaper .