If you want to make synthetic fuels it’s similar effort and efficiency to make methane as it is to make hydrogen. In fact converting one to the other is trivial and the conversion from methane is how we actually make hydrogen today.
Hydrogen has a lot of issues. It’s a pain to store since it’s corrosive and does not liquify or stay liquified without cooling and extremely strong pressure vessels. Methan is already used pretty commonly. A lot of busses run on methane today.
So we’re taking methane, a fuel that’s used in transit already and that we gave a shortage if right now since it makes fertilizer and the hormuz straight is blocked. We’re taking that precious methane and converting it to hydrogen (not at all green to do this and the carbon goes into the air at this point) and then we’re awkwardly transporting this and storing it in cars with all the problems that has just to burn the hydrogen in the car pretending that we never released co2 in the process.
Now you might say ‘yeah but in theory you could use electricity to make hydrogen’ and I’ll point out that’s grossly inefficient to just using a battery electric vehicle and it’s not at all done at an industrial scale due to the reality that it was always just a way to sell fossil fuels with an obfuscation of where the release of carbon occurs and never intended an actual reasonable way to store electricity.
And increasingly I think that is being quietly admitted. It has a weird afterlife in buses (where the range potential is interesting for long-range intercity routes), but even there, at this point, it’s marginal. The Irish transport authority placed an order a few years back for 800 BEV buses… and three hydrogen buses, for instance. A decade ago, BEV buses and hydrogen buses were both basically experimental. Today BEV buses are ordered by the thousand; hydrogen buses are still experimental.
(Also I expect hydrogen _trains_ to hang around as a concept for a while, and it _may_ actually be viable there where adding overhead lines is not.)
> It would allow legacy vehicles to stay on the road
How? Hydrogen cars _are electric cars_; they just have a fuel cell instead of a battery. If you’re imagining that they have, er, a four stroke engine that they burn hydrogen in or something, yeah, that’s not a thing.
I suppose if you wanted to get _really_ weird you could have a hydrogen turbine car? But again, that’s nothing like current petrol cars tech (and would be horribly inefficient relative to the fuel cell ones).
You need to use energy to create hydrogen - and the energy required is 5x what would be required to just store the same amount of energy as electricity in a battery.
55kWh of electricity for hydrogen generation results in around 10kWh at the wheels of a hydrogen car.
Or you can just shove the 55kWh directly to an EV battery.
Also, a hydrogen car needs a battery anyway. Just make a bigger battery and skip the hydrogen part. Cheaper, simpler, lighter,…