The fuel in fact doesn't come from the Sun, but from other stars that went super nova before the solar system was formed. Normal fusion in stars in not hot enough to produce such heavy elements.

I'd love to know more about how heavy elements got from the sun into the interior of our planet and then back out to near the surface again. Where can I learn about this process?

ahhh you got me thats the only other source of energy in our solar system but thats the exception that proves the rule.