Takes 31.7 megajoules (about 30,046 btu) of energy to split a liter of water into hydrogen and oxygen using electrolysis. Now expand that to 22 US gallons (83.3 liters) and you need a little over 2.5 million btu just to produce the available hydrogen.
Exactly. Until someone comes up with some magic to crack the Hydrogen from Oxygen as needed, its little more than a novelty for cars.
Hell I wish they would come up with decent fuel cell tech for home use.
That's only a part of the energy needed. You have to compress the hydrogen considerably to use it. Compressing gases takes a LOT of energy.