Around 50% is used for road transport, though, which is poised to be replaced and was one of the parent poster's main points.

We knew how to make synthetic hydrocarbon one hundred years ago. Nazi Germany used the Fischer Tropsch process to make synthetic fuel after the Royal Navy blockaded their oil import. The only reason we're still digging up fossil fuel is because it's cheap. According to some calculation, green hydrocarbon from atmospheric CO2 and electrolytic hydrogen could be commercially viable when fossil petroleum reaches $200/barrel , which is really not that far off.