The Natural Philosopher wrote:
[snip]

Taking it locally, the prime energy sources in the Earth, are the big
fusion reactor in the sky, and the heat and energy still left in the
earth. We have dug up or pumped most of the low hanging chemical fruit -
carbon fuels - already.

No, thats ******** the major part of carbon fuel stocks remain in the
ground. Even if we had reached "peak oil" - and there's no evidence that we
have - the shape of the curve is skewed to the right so there would still
be more oil below than above. For coal, we haven't even scratched the
stocks remaining despite two centuries of use.

All that is left is nuclear fuel,

********.

but there's a lot of that still left..although the low hanging fruit of
Uranium 235 may not be in such abundance.

There's about a century of nuclear fuel in the UK. The only barrier to
using it is the weakness of the knees of politicians.