How do you get rid of the C in the CH4, though?

By the same token, I've always thought it would be interesting if someone came up with a way to retrofit gas stations with something that could split the hydrocarbon molecules without burning them. Then we'd really be able to reuse existing infrastructure (handwaving away the storage-density problem of course, which the subject of this article might help with.)

But same problem... the carbon and the hydrogen really, really like to hang out together.

You take c from the co2 when producing ch4 synthetically.

You then reform the co2 on combustion.

Fwiw methane to hydrogen and back again is trivial. It’s how hydrogen is predominantly made today. You can indeed make a hydrogen fuel station from methane. It’s just that it’s really really dumb to do that when hydrogen is so inefficient in an engine and so hard to store. You should just use methane all the way.