Your thinking of charcoal, which are chunks of wood converted into almost pure carbon by heating them above their combustion temperature in a low oxygen environment. He was talking about coal that was mined out of the ground. Plants from an ancient swamps that didn't decompose, but were converted into almost pure carbon from millions of years of heat and pressure from being buried.

I have electric! The coal stove is backup, some people use wood as a backup. It's not uncommon