By “burn it” I meant turn it into charcoal… Charcoal averages 80% carbon (range 50-95%), whereas depending on the type coal ranges from 60-92% carbon, with the purest type, anthracite, being 86-92% carbon
Given a mass production system would likely result in more uniform carbon content near the top of the range, I don’t think it’s unreasonable to suggest that they could be swapped out pretty easily