[nuccy]

Hydrogen is not a good (at the moment at least) source of energy or fuel for cars or industry (chemically speaking, obviously much better together with Deuterium and Tritium for fission, though we are still from such a technology). Steam reforming, which is currently the most common way of hydrogen production, uses natural gas and water and produces plenty of CO2 [1]. Nice summary as for cars fuel application here [2].

[1] https://en.m.wikipedia.org/wiki/Hydrogen_production

[2] https://m.youtube.com/watch?v=f7MzFfuNOtY

[pfdietz]

Hydrogen is an answer to the question "how do renewables serve 100% of the grid?". It enables renewables to cover that last 10% or so, and rare prolonged dark/calm periods, without excessive amounts of overcapacity or batteries.