Hydrogen vs. Battery Electric Cars

You probably won't read this, but i think you really understated the importance of the efficiency massively! Hydrogen fuel cell cars use 2-3 times the energy that a battery electric vehicle would use. In places like germany or switzerland and certainly a lot more places we don't have those 2-3 times more energy in the transportation sector (which makes up a large chunk of the energy demand). That means that in such places the energy transition and thereby the paris climate goals of reaching net zero CO2 emissions by 2040 would be virtually impossible. 

That's why regenerative energy systems experts like Prof. Volker Quaschning and many others make it pretty clear that BEV's have to be the future. If fuel cell powered cars become too popular it would endanger the energy transition. To save it we would have to drive 2-3 times less kilometers then with BEV's. Does anyone really want that? The problem become even worse if with e-fuels, since you also need hydrogen for it, but have to process it further, which causes more energy losses and you'll burn it in internal combustion engines, which are highly inefficient. That would mean we'd need about 6 times more energy for the same distance. So that would also endanger the energy transition in case this would spread too much. Or if you want to see it this way: The more inefficient the technologies that we use the longer it will take to complete the energy transition, the more expensive it will probably be and the less we'll be able to do/the more we'll have to give up. 

The bottom line is that you can't look at any potential technology that helps us achieve carbon neutrality by itself. You will always have to look at it in the context of the energy system it's working in. Which means that it's crucial to read the scientific literature in regards to 100 percent renewable or CO2 neutral energy systems. 

Another thing to consider are EROEIS. Renewables can have quite low EROEIS therefore we have to be carefull when combining renewables with very inefficient technologies. We don't want to end up using more energy then we get back in the form of work i.e. we don't want our energy sources to end up as energy sinks. So if a solar panel has an EROEI of 3 (it hasn't) and i use it to produce e-fuels to drive an internal combustion engine with (losses of over 90 percent), then i won't have gained any energy. I lost energy in the overall process i.e. i made life harder compared to having done nothing.

PS:
I'm not bashing hydrogen by the way. The scientific literautre seems to be quite clear about the fact that we'll have to produce hydrogen to produce some amount of e-fuels and as an long term energy storage system (to deal with the seasonal variability of renewables), but because of the losses it's not a good idea to use them anywhere where it isn't completely necessary. For cars it's not necessary. It would be a huge waste of renewable energy and we already have too little of it and are building renewable energy sources too slowely to stay below 1.5°C of warming. Why do something that will require even more renewable energy sources?