Science or Fiction
The majority of hydrogen is produced by electrolysis from water, and is as clean as the source of electricity used in this process.
The global production of hydrogen is more than 70 million metric tons annually (which could theoretically produce 2.3 billon MWh of electricity – US energy production is 4.1 billion MWh annually). https://www.energy.gov/eere/articles/10-things-you-might-not-know-about-hydrogen-and-fuel-cells
Hydrogen is about 2.8 times as energy dense as gasoline by weight. https://afdc.energy.gov/fuels/hydrogen_basics.html#:~:text=The%20energy%20in%202.2%20pounds,driving%20range%20of%20conventional%20vehicles.
Skeptical Quote of the Week.
“But too often, “common sense” is the safe harbor of ignorance and an excuse for intellectual laziness. They don’t need facts because they already know the truth—their common sense has spared them the effort of investigation or thought.” Randy Wayne White “Captiva” Chapter Four