Does Hydrogen fuel require vast amounts of electricity?
The overall “hydrogen economy” is quite complex. Many “easy” options are not really very economical at all. MOST IMPORTANTLY – remember that ALL energy tends towards increased entropy (disorder), so changing the form of an energy source always includes losses of the original energy potential.
As with all energy production and usage, a truly sustainable approach must include the energy and materials that must go into the infrastructure and production requirements. “Solar energy” isn’t free! It takes additional energy and material resources to build the equipment necessary to collect solar energy. The same is true with hydrogen.
There are many ways to produce elemental hydrogen for use as a fuel. All of them require more energy than can be recovered from the use of the hydrogen as a fuel. The utility is in terms of accessibility, storage, transport, use, and residues (pollution). Generation of hydrogen gas by electrolysis of water is energy-intensive.
The same is true for the full cycle of hydrogen production from hydrocarbon cracking. Production by catalytic decomposition of water by solar thermal systems is the most sustainable, but again for the overall economy you need to include the cost and energy of system construction, and the collection, storage and transport of the hydrogen. Production of liquid hydrogen from the gas requires huge amounts of energy.