[Retric]

There is still crazy amounts of coal around WV very near the surface for example. Easily enough to bootstrap an industrial revolution multiple times. It's not a question of mining you can pick coal up from open top mines on the surface with your hands. You even see coal seams where they simply cut down to build roads a little.

We don't use it because the high sulfur content requires more expensive scrubbers to meet modern air quality standards. And due to the drop in solar / wind energy plus concerns about climate change it's likely to be available long term.

PS: US coal supply is estimated around 350 years at current production levels. Though that's also a low estimate based on proven reserves. Further, if you consider the Oxigen in the atmosphere needed to be separated from Carbon in the first place you should realize there is quite a bit of fossil fuels sitting around.