Why the heck would you use something so difficult/expensive to store & transport like Hydrogen?
If energy is expensive than it's makes more sense to store it in batteries than hydrogen since batteries are about 3X as efficient as the hydrogen cycle.
If energy is cheap it makes more sense to use about twice as much energy to capture and attach carbon molecules to that hydrogen to create a hydrocarbon resulting in something that's easy to store and transport, and that uses existing infrastructure.
You don't have to transport it very far if you generate it onsite straight in the hydrogen powerplant that'll turn it back into electricity with between 40 to 60% efficiency
If we follow your 3rd paragraph and turn the hydrogen into hydrocarbons, not only do you lose efficiency in that process, you make CO2 as a byproduct of combustion again
Nobody is interested in storage that turns your carbon-free green energy back into greenhousing energy
The reason you might want hydrogen instead of batteries is just cost, I guess.
> Nobody is interested in storage that turns your carbon-free green energy back into greenhousing energy
If you make your hydro-carbons with captured carbon, the process is slightly carbon-negative. ~10% of hydrocarbons are not burned, they're turned into plastic or lubricants etc. So for every 10 carbons you take from the air, only 9 are released back.
If energy is expensive than it's makes more sense to store it in batteries than hydrogen since batteries are about 3X as efficient as the hydrogen cycle.
If energy is cheap it makes more sense to use about twice as much energy to capture and attach carbon molecules to that hydrogen to create a hydrocarbon resulting in something that's easy to store and transport, and that uses existing infrastructure.