Or hydrogen production, hydrogen fuel cells, and hydrogen-based engines. Hydrogen can be created with electrolysis using solar, wind, or nuclear power. Hydrogen-based vehicles have a much better range. Refueling a hydrogen vehicle quicker than charging a battery. Also, it is easy to transport hydrogen to locations where there is no power grid.
(I guess we should do both, but I feel like hydrogen as a fuel seems to be ignored.)
I feel that if anyone took hydrogen seriously, they'd start talking about anhydrous ammonia. This compound actually contains more hydrogen by volume and pressure than elemental hydrogen does. It doesn't have the embrittlement issues that elemental hydrogen has. Ammonia liquefies at a much higher temperature and has a much higher heat of vaporization, which makes it easier to handle. It is a hazardous fuel, but not really more so than gasoline and definitely less so than elemental hydrogen. Anyway, there is already a well-developed infrastructure for handling anhydrous ammonia, because it is regularly used in agriculture. Any cheap and environmentally friendly process that produces hydrogen also produces ammonia, because ammonia is just hydrogen plus nitrogen.
Because I very rarely see mention of ammonia as a fuel, I conclude that no one is seriously attempting to develop hydrogen fuel cells.
Hydrogen is hard to handle - it is very good at leaking, including through things not normally thought of as porous like metals, and it has low energy density unless under high pressure.
Synthetic CH4 from H2+extracted CO2 seems more likely to happen.
(I guess we should do both, but I feel like hydrogen as a fuel seems to be ignored.)