and at some point in our future we will run out of petrol. i would prefer if we continued to use the rest of the worlds reserves before tapping all of ours.
Out of natural, underground reserves of crude oil on Earth, you mean. We don't technically have to run out of "petrol".
Hydrocarbons are simply carbon, hydrogen and oxygen. (In practice, also nitrogen, sulfur, et al, but let's keep it simple.) What is a large chunk of earth's atmo composed of? If you have cheap enough energy, we can make a very large supply of relatively cheap hydrocarbons out of air. Pick a corner of the US without too much NIMBY idiots, install a whole mess of nuclear plants (I'd do a mix of reactors so we could also do R&D on various designs) and start making hydrocarbons. Expensive in the short run, necessary in the very long run.
It's quite amazing what humanity can do, and chooses not to do.