Hydrogen (as a gas) does not remain naturally on our planet's surface so it must be produced and contained, both of which require power of some kind. It is robbing Peter to pay Paul in other words. The question becomes, 'Can we pay Paul more than we have to rob from Petar?'. Not likely. One always loses power when it is converted in any way. Some law of thermodynamics I think.

Stationary power applications (such as supplying your home electrical power needs) using hydrogen just don't make sense for most situations. This will remain true until practical chemical / biological methods of producing and storing hydrogen (using little or no power) are developed.

For mobile applications (fuel cell driven vehicles), hydrogen as a power source only makes sense if the hydrogen is produced using totally green methods (e.g. sun or wind). There is, however, a relatively new system for internal combustion engines that is quite interesting. Basically, an electrolyzer is hooked up to the car's generator and the hydrogen produced is fed into the carburetor. The hydrogen is produced 'on-demand' using excess power from the car's generator that is currently just being wasted. Fuel savings have been reported at between 10 and 40 percent.

I drive a hybrid (2003 Honda Civic) and this helps me see how this is practical. All cars, hybrid or not, have a generator that is capable of running all its electric needs (engine spark, headlights, radio, etc.) with enough left over to charge the battery when needed. In most cars, a voltage regulator 'disconnects' the generator 'intermittently' when generator power output exceeds demand (which is most of the time).

This new system makes hydrogen with that excess power which it feeds back into the engine. There are some similarities with the way hybrid technology works which I have learned quite a bit about from research and experience (I get 45 mpg with zero freeway/long distance driving).

My feeling is that this new 'hydrogen booster' system is even more efficient and far less expensive to implement than current hybrid technology. I want to install the system in my hybrid. There is some 'duplication' meaning that I would not get as much improvement as a non-hybrid Civic with everything else the same. But I think it would still be better than either system alone.