Thing about batteries is.
From an environmental standpoint, both mining the raw materials and producing the batteries uses a lot of energy and produces a lot of pollution.
Morally, many raw materials for batteries come from desperately poor conflict zones, so you have megacorps staffing mines with slavery and child labor, paying local warlords/dictators for permission to operate, having those warlords/dictators kill protesters and union organizers, etc.
If we can get a hydrogen economy working, and the equipment and technology don’t need conflict minerals or polluting heavy industry to manufacture, it would be a boon for the world both practically and morally.
But that’s a big if.
Hydrogen can be stored in underground caverns and that can be relatively easily scaled to TWh. Electrolysis and fuel cell can get you 70% or so of your electricity back. So it is less efficient then batteries. However there might be a place for hydrogen as seasonal storage. Also the storage makes sense as quite a few processes use hydrogen anyway.
So there is a use case, but right now we mostly should just add renewables and batteries. We are nowhere close to a solar/wind grid, which does actually need seasonal storage. Also grid size helps a lot and there are options such as burning waste.
Electrolysis of the most expensive process (PEM) is around 80% efficient by itself. The more common methods are 70%. Anything that uses it after that only drops it further. Fuel cells max out at 60%, which means that electrolysis to electrical output efficiently is about 50% altogether in the very best case.
Some of the better internal combustion engines are reaching about the same.
