This kind of question is so strange...
First of all, from an economic point of view, it is not profitable to electrolyze water as an energy source ; and oxygen equals hydrogen The energy released during combustion. However, losses are inevitable during the electrolysis process.
Second, electricity remains the most convenient energy source to transport and use so far, and it is also relatively safe. Hydrogen is very explosive and very impractical to transport. Thus, except in certain very specific places, hydrogen or liquid hydrogen is rarely used as fuel.