OK, let’s think about this:
He makes a list and marks it with who is naughty or nice — suggesting that the proportion of naughty children to nice children is near equal and somewhat dynamic. If there was a significant skew toward naughty or nice he would employ blacklist/whitelist procedures to make delivery planning easier. This implies that there has to be a LOT of coal because nearly half of all little boys and girls are “naughty”. (This also raises the question of whether the list is maintained in real-time and if they use transactional guarantees to ensure that the integrity of the list is maintained — but I won’t go into that here — maybe next year…)
Is there a separate just-in-time delivery process for coal? If there were and considering the volume of coal delivery required, much more Christmas lore would be directed at that system. I think we can discount the JIT coal delivery hypothesis.
Is there a supply of coal on board that we can’t see? Probably not because the mass of the sleigh, toys and coal when Santa initiates his route would be considerable — and if he’s hauling coal, it would probably be for an additional power source to supplement the reindeer on the first half of the delivery route when the sleigh and cargo are heaviest. But coal must not be used for fuel or the sleigh would have a large boiler and smoke stack which is certainly not in any of the traditional images of the sleigh.
Is there coal mixed in with the bag of toys? If so, wouldn’t the good children’s presents be sooty and grimy from the coal?
Are there separate compartments in the bag for presents and coal? If the density of the coal is significantly different than that of the toys, that may make the bag unwieldy to manage. Also carrying a bag with a significant amount of coal into every home probably violates some local and regional ordinances.
Does he use his super Santa strength to crush the bad children’s presents into black lumps? That seems especially cruel and would consume a considerable amount of energy. And it’s probably not efficient to produce a toy and then crush it down into a lump just prior to delivery. (Though I admit this option appeals to me at some perverse level.)
No, I think the answer is elsewhere. Look again at the configuration of the sleigh. There is a component of the system architecture that can produce dark worthless lumps. In fact, there are eight of them (nine if you count Rudolf). So it’s not coal that’s being left to the naughty children…
I hope you’ve been good this year.