There’s a heck of a lot of fossil fuels in the world. Loads of it. In 2005 they found 3000 billion tons of the stuff near Norway. Yes, it is under water and nearly impossible to mine at present. But technology changes. So if world coal reserves are about 250 years worth, that makes it about 750 years more for a total of about 1000 years worth of coal. One can only wonder how much more coal is under the ground and water of the world. The bottom line is that we’re drowning in energy resources. We don’t run out for thousands of years, or never.