This may be an option for emissions free vehicles that don’t have the space or payload for a big heavy battery. It could also be used for high torque applications where an electric motor and its battery would be very expensive and heavy, as stated in the article.

Think of the Hydrogen part as being more like the battery. For example, imagine you're running a solar power plant, but you're making more power than your town needs. You can use the extra electricity to make Hydrogen on the sunny days, and then use that Hydrogen to make power on the cloudy days. You can also do this with normal power plants to account for the spikes in energy demands over the day (folks use more power during the day than they do at night, for example).

When it comes to vehicles, we want to store energy in a way that's lightweight & portable. Compared to the old lead-acid batteries, Hydrogen make sense on paper. Not so sure they stack up against all the new battery types that are coming out now though. But that's where the race is - figuring out which system is going to 'win' for the vehicles of the future. To me, that's the interesting part here - most Hydrogen cars use a fuelcell to generate electricity, and use an electric motor to spin the wheels. This seems to be more like a traditional gasoline engine, but driven by Hydrogen.

Portable energy Independence for countries that have neither oil nor batteries. Domestically

Something to do with all the water when the oceans start rising.

It's an internal combustion engine using argon as a working fluid.