Up next, coal furnace!
I lived in England in 1975-1976. Had a house that was all electric (damned expensive) but it did have one little boiler in the hallway downstairs that heated a panel in the dining room AND aided the electric water heater to fill an attic mounted tank.
I used to buy bags of anthracite coal and ran that in the little boiler to have plenty of hot water and heat up things a bit. Burned clean, not much ash at all. Only trouble was getting a pre-fire going to light it up. For that, I had several pallets in the garage that I used to bust up with a small hand axe the wife bought me in Banbury. I still have the axe and the wife...